[Federal Register Volume 60, Number 15 (Tuesday, January 24, 1995)]
[Rules and Regulations]
[Pages 4664-4709]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-817]




[[Page 4663]]

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Part II





Environmental Protection Agency





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40 CFR Part 131



Water Quality Standards for Surface Waters of the Sacramento and San 
Joaquin Rivers, and San Francisco Bay and Delta, California; Final Rule

  Federal Register / Vol. 60, No. 15 / Tuesday, January 24, 1995 / 
Rules and Regulations   
[[Page 4664]] 

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 131

[OW-FRL-5084-4]


Water Quality Standards for Surface Waters of the Sacramento 
River, San Joaquin River, and San Francisco Bay and Delta of the State 
of California

AGENCY: Environmental Protection Agency.

ACTION: Final rule.

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SUMMARY: This final rule, required under Section 303 of the Clean Water 
Act, is part of an interagency effort designed to ensure that the fish 
and wildlife resources of the San Francisco Bay/Sacramento-San Joaquin 
Delta Estuary (Bay/Delta) are protected and to minimize the likelihood 
of future listings of Bay/Delta species under the Endangered Species 
Act. The Bay/Delta is the West Coast's largest estuary, supplying 
habitat for over 120 fish species and large populations of waterfowl. 
Over the past two years, the U.S. Environmental Protection Agency (EPA) 
has worked closely with the Departments of the Interior and Commerce, 
as well as the State of California, to address the severe and 
continuing decline of Bay/Delta fish and wildlife resources. This 
decline has been so severe that a number of fish species, including the 
winter-run chinook salmon are considered threatened or endangered under 
the Endangered Species Act. In coordinating their respective actions in 
the Bay/Delta, the Federal agencies endorsed an ecosystem (as opposed 
to a species-by-species) approach. EPA's final rule establishes four 
sets of water quality criteria protecting habitat conditions in the 
estuary.

EFFECTIVE DATE: This rule shall be effective February 23, 1995.

ADDRESSES: The public may inspect the administrative record for this 
rulemaking, including documentation supporting the criteria, and all 
public comments received on the proposed rule at the Environmental 
Protection Agency, Water Management Division, 11th Floor, 75 Hawthorne 
Street, San Francisco, California 94105 (Telephone Sara Hedrick at 415-
744-2200) on weekdays during the Agency's normal business hours of 9 
a.m. to 5 p.m. A reasonable fee will be charged for photocopies. 
Inquiries can be made by calling Sara Hedrick at 415-744-2200.

FOR FURTHER INFORMATION CONTACT: Judy Kelly, Bay/Delta Program Manager, 
Water Management Division, W-2-4, Environmental Protection Agency, 75 
Hawthorne Street, San Francisco, California 94105, 415/744-1162.

SUPPLEMENTARY INFORMATION: This preamble is organized according to the 
following outline:

A. Background
    1. Introduction
    2. Background
    a. Environmental Concerns
    b. State Designation of Uses in the Bay/Delta
    c. EPA Activity Under Clean Water Act Section 303
    d. Post-Proposal Activities
B. Statutory and Regulatory Background
C. Description of the Final Rule and Changes From Proposal
    1. Estuarine Habitat Criteria
    a. Overview
    b. Detailed Discussion
    (1) Proposed Estuarine Habitat Criteria
    (2) Technical Changes to the Estuarine Habitat Criteria
    (i) Underlying Computational Revisions
    (ii) Using a Sliding Scale
    (iii) Moving to Monthly Compliance
    (iv) Alternative Measures of Attaining the Criteria
    c. Revised Estuarine Habitat Criteria
    2. Fish Migration Criteria
    a. Overview
    b. Detailed Discussion
    (1) Proposed Rule
    (2) Final Fish Migration Criteria
    (i) Revised Method of Selecting Criteria Index Values
    (ii) Use of Continuous Function
    (iii) Measuring Attainment Through Actual Test Results
    (3) Fish Migration Criteria as Multispecies Protection
    3. Fish Spawning Criteria
    a. Proposed Rule
    b. Comments on Proposal and Final Criteria
    4. Suisun Marsh Criteria
D. Public Comments
E. Executive Order 12866
F. Regulatory Flexibility Act
G. Executive Order 12875
H. Paperwork Reduction Act

A. Background

1. Introduction

    This section of the Preamble introduces the topics which are 
addressed subsequently, provides a brief description of the 
environmental issues at stake in the San Francisco Bay/Sacramento-San 
Joaquin River Delta Estuary (Bay/Delta), and reviews the U.S. 
Environmental Protection Agency's (EPA or the Agency) recent 
involvement in these issues. Section B of this Preamble describes the 
statutory framework of section 303 of the Federal Water Pollution 
Control Act (33 U.S.C. 1251 to 1387) (CWA or the Clean Water Act), as 
well as the regulatory process for developing and revising water 
quality standards. In addition, Section B summarizes the recent actions 
of the State of California (State) and EPA under section 303 of the 
CWA. Section C describes the Final Rule, focusing especially on the 
changes from the criteria proposed at 59 FR 810, January 6, 1994 
(Proposed Rule). Sections D, E, F, G, and H discuss the public 
comments, the requirements of Executive Order 12866, the Regulatory 
Flexibility Act, Executive Order 12875, and the Paperwork Reduction 
Act, respectively.
    In addition to publishing the Proposed Rule, EPA, on August 26, 
1994, at 59 FR 44095, published a Notice of Availability announcing the 
availability of two documents prepared since the close of the comment 
period. The first of these documents was a summary of a series of 
scientific workshops on EPA's proposed Fish Migration criteria that 
were sponsored and facilitated by the California Urban Water Users 
(CUWA) and four environmental organizations. The second document was an 
internal EPA staff paper presenting a reformulation of the Fish 
Migration criteria based upon the comments at the workshops. EPA 
accepted public comments on the issues raised in these two documents 
until September 30, 1994. EPA received two written comments in response 
to the Notice of Availability.
    This final rule satisfies EPA's obligations under a settlement 
agreement approved and entered as an order in Golden Gate Audubon 
Society et al. v. Browner (E.D. Cal. Civ. No. 93-646 (LKK)).

2. Background

a. Environmental Concerns
    The Bay/Delta is the West Coast's largest estuary, encompassing 
nearly 1600 square miles, and draining over 40 percent of California. 
The Bay/Delta is the point of convergence of California's two major 
river systems--the Sacramento River system flowing southward and 
draining a large part of northern California, and the San Joaquin River 
system flowing northward and draining a large part of central 
California. These two river systems come together at the western tip of 
the Delta, forming an estuary as fresh water mixes with marine water 
through a series of bays, channels, shoals and marshes and ultimately 
flowing into San Francisco Bay and then to the Pacific Ocean.
    The Bay/Delta constitutes one of the largest systems for fish 
production in the country, supplying habitat for over 120 fish species. 
It also comprises one of the largest areas of waterfowl habitat 
[[Page 4665]] in the United States, providing a vital stopover for rest 
and feeding for more than one-half of the waterfowl and shorebirds 
migrating on the Pacific Flyway. Within the boundaries of the Bay/Delta 
is the Suisun Marsh, the largest contiguous brackish water marsh in the 
United States.
    The Bay/Delta is also the hub of California's two major water 
distribution systems--the Central Valley Project (CVP) built and 
operated by the U.S. Bureau of Reclamation (USBR) and the State of 
California's State Water Project (SWP). These two projects account for 
approximately 60% of the watershed's diversions (San Francisco Estuary 
Project (SFEP) 1992). In addition, at least 7,000 other permitted water 
diverters, some large and some small, have developed water supplies 
from the watershed feeding the Bay/Delta estuary (California State 
Lands Commission 1991). Together, these water development projects 
divert, on average, 50% of the natural flow in the Bay/Delta estuary 
(SFEP 1992). Most of the State's developed water--75 to 85 percent--is 
used for irrigation purposes by agriculture, irrigating over 4.5 
million acres throughout the State. The Bay/Delta watershed also 
provides part or all of the drinking water supply for over 18 million 
people.
    In large part due to the effects of these water diversions, and as 
discussed in more detail in the preamble to the Proposed Rule, the fish 
and wildlife resources in the Bay/Delta estuary have deteriorated 
drastically over the past twenty years. One common measure used to 
quantify this deterioration is the Striped Bass Index (SBI) (a measure 
of the relative abundance of young striped bass in the estuary). The 
SBI measures the relative health of an indicator species for the Bay/
Delta, the striped bass. In its 1978 Water Quality Control Plan (1978 
Delta Plan), the California State Water Resources Control Board (State 
Board) committed to maintaining an SBI value of 79. Since that time the 
SBI has never attained its targeted value of 79, but instead has 
plummeted to unprecedented low values.\1\

    \1\During the 1980's, the SBI averaged approximately 23.5, and 
in 1985 reached an all-time low of 4.3. Some of the decline in the 
SBI may be attributable to drought conditions in the late 1970's and 
again in the late 1980's. In all but two years since the 1978 Delta 
Plan was adopted, the SBI has ranged from 4.3 to 29.1, a substantial 
shortfall from the stated goal of 79.
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    The precipitous decline in striped bass is indicative of the poor 
health of other aquatic resources in the Bay/Delta estuary. Several 
species have experienced similar declines, including chinook salmon 
(the winter-run of chinook salmon has recently been reclassified as an 
endangered species under the Federal Endangered Species Act, 16 U.S.C. 
1531 to 1540 (ESA)), Delta smelt (listed as a threatened species under 
the ESA), and the Sacramento splittail (recently proposed for listing 
as a threatened species under the ESA). The California Department of 
Fish and Game (California DFG) recently testified that virtually all of 
the estuary's major fish species are in clear decline. (CDFG 1992b, 
WRINT-DFG-8)\2\ Another recent report suggests that at least three more 
of the Bay/Delta estuary's fish species (spring-run Chinook salmon, 
green sturgeon, and Red Hills roach) qualify for immediate listing 
under the ESA (Moyle and Yoshiyama 1992). Furthermore, the decline in 
aquatic resources is not limited to fishes. One recent workshop noted 
that the available data ``indicate clearly that species at every 
trophic level are now at, or near, record low levels in the Delta and 
in Suisun Bay.''\3\ (SFEP 1993) The ecological communities under stress 
include the plant and animal communities in the tidal portions of the 
brackish water marshes adjacent to Suisun Bay (Collins, J.N. and T.C. 
Foin, 1993).

    \2\If a reference was presented to the State Board during one of 
its hearings, this preamble will present citations in both the 
standard scientific form and in the State Board hearing record form. 
Accordingly, the eighth exhibit submitted by California DFG at the 
Board's interim water rights hearings in the summer of 1992 is cited 
as indicated.
    \3\The workshop report went on to state that this low level of 
biological diversity was ``not surprising considering the recent 
drought, the introduction of exotic species, and the increased 
diversion of water.''
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b. State Designation of Uses in the Bay/Delta
    Under section 303(c) of the CWA, states review their water quality 
standards every three years and submit any new or revised standards to 
EPA for approval or disapproval (the ``triennial review''). A water 
quality standard for a waterbody consists of two components: (1) 
Designated uses for the waterbody and (2) water quality criteria which 
support such designated uses.\4\ In California, designated uses are 
equivalent to state law ``beneficial uses'' and criteria are equivalent 
to state law ``water quality objectives.'' Thus, the water quality 
objectives and beneficial use designations adopted under the California 
Water Code serve as water quality standards for purposes of section 303 
of the CWA.

    \4\In addition, a state's criteria must be consistent with the 
state's antidegradation policy. The federal regulations provide 
that, at a minimum, the state's policy must maintain ``[e]xisting 
instream water uses [those existing in the waterbody at any time on 
or after November 28, 1975] and the level of water quality necessary 
to protect the existing uses. * * *'' 40 CFR 131.12(a)(1).
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    Pursuant to state and federal law, the State Board, on May 1, 1991, 
adopted State Board Resolution No. 91-34, formally approving the 1991 
Bay/Delta Plan. The Plan restated the specific designated uses that had 
been included in the 1978 Delta Plan and related regional board basin 
plans. As restated in the 1991 Bay/Delta Plan and submitted to EPA for 
review under the Clean Water Act, the designated uses for waters of the 
Bay/Delta included the following: Agricultural Supply, Cold and Warm 
Fresh-Water Habitat, Estuarine Habitat, Fish Migration, Fish Spawning, 
Groundwater Recharge, Industrial Process Supply, Industrial Service 
Supply, Municipal and Domestic Supply, Navigation, Contact and Non-
Contact Water Recreation, Ocean Commercial and Sport Fishing, 
Preservation of Rare and Endangered Species, Shellfish Harvesting, and 
Wildlife Habitat.\5\

    \5\As explained in more detail below, under certain 
circumstances a state may revise or even remove designated uses. 
However, in the Bay/Delta context, the State Board has made no 
effort to revise the designated uses adopted and restated in the 
1991 Bay/Delta Plan.
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c. EPA Activity Under CWA Section 303
    As explained in detail in the preamble of the Proposed Rule, the 
serious environmental crisis for fish and wildlife resources in the 
Bay/Delta has been the source of an ongoing dialogue between EPA and 
the State for many years. Pursuant to section 303(c)(3) of the CWA, EPA 
reviewed the 1978 Delta Plan in 1980. While EPA approved the Plan, it 
was concerned that the 1978 Delta Plan standards would not provide 
adequate protection of striped bass and the estuary's fishery 
resources. EPA therefore sought and received assurances from the State 
Board as to the interpretation of the standards, and secured the State 
Board's commitment to review and revise the 1978 Delta Plan standards 
immediately if there were measurable adverse impacts on striped bass 
spawning, or if necessary to attain ``without project'' levels of 
protection for the striped bass as defined by an SBI value of 79. The 
``without projects'' level of protection is the level of protection 
that would have resulted in the absence of the state and Federal water 
projects (the SWP and the CVP). EPA also conditioned its approval on 
the State Board's commitment to develop additional criteria to protect 
aquatic life and tidal wetlands in and surrounding the Suisun Marsh. 
The State Board concurred with these [[Page 4666]] interpretations in 
its letter to EPA dated November 21, 1980.
    As fish and wildlife resources in the Bay/Delta continued to 
decline, EPA on several occasions expressed its continuing concern to 
the State Board about the need to develop standards that would 
adequately protect these resources. Throughout the first and second 
triennial reviews ending in 1981 and 1985, EPA urged the State Board to 
review and revise the 1978 Delta Plan in accordance with EPA's 1980 
approval letter. After its second triennial review, in a letter to EPA 
dated June 23, 1986, the State Board acknowledged that the 1978 Delta 
Plan standards were not adequate to protect the estuary's fishery 
resources. It then outlined the hearing process it was planning for 
revising the standards. In response, and as part of its consideration 
of the State Board's second triennial review, EPA, on June 29, 1987, 
sent a letter to the State Board stating that EPA could no longer 
approve the striped bass survival standards (or the related provision 
allowing relaxation of the spawning standard in drier years) because 
these standards did not adequately protect the designated fish and 
wildlife uses. EPA recognized, however, that the State Board had 
initiated new hearings to revise the 1978 Delta Plan standards. EPA 
therefore indicated that it would await the results of the new hearings 
and approve or disapprove the revised standards after the State Board's 
submission to EPA of a complete set of revised standards. Following the 
first phase of the new hearings, the State Board in November 1988 
issued a draft Plan that included revised salinity and flow standards 
to protect the fisheries and other designated uses (SWRCB 1988). The 
State Board subsequently withdrew that draft Plan, however, and issued 
a revised workplan that served as the basis for the State Board's 
present Water Quality Control Plan for Salinity for the San Francisco 
Bay/Sacramento-San Joaquin Delta Estuary (1991 Bay/Delta Plan).
    The 1991 Bay/Delta Plan, which the State Board submitted to EPA for 
review on May 29, 1991, amended certain salinity criteria and adopted 
new temperature and dissolved oxygen criteria for specified locations 
in the estuary. The 1991 Bay/Delta Plan did not, however, revise the 
earlier 1978 Delta Plan to address EPA's longstanding concerns about 
adequate protection for the designated fish and wildlife uses of the 
Bay/Delta.
    On September 3, 1991, EPA approved in part and disapproved in part 
the provisions of the 1991 Bay/Delta Plan. EPA's letter found that 
``[t]he record * * * does not support the conclusion that the State has 
adopted criteria sufficient to protect the designated uses'' of the 
estuary. The designated uses at risk, as defined by the State Board, 
include Estuarine Habitat, and also Cold and Warm Water Habitat, Fish 
Migration, Fish Spawning, Ocean Commercial and Sport Fishing, 
Preservation of Rare and Endangered Species, Shellfish Harvesting, and 
Wildlife Habitat. In addition to its general finding that the 1991 Bay/
Delta Plan did not contain sufficient criteria to protect the 
designated uses, EPA also disapproved the absence of salinity standards 
to protect the Estuarine Habitat and other fish and wildlife uses in 
the Suisun, San Pablo, and San Francisco Bays and Suisun Marsh, the 
absence of scientifically supportable salinity standards (measured by 
electrical conductivity) to protect the Fish Spawning uses of the lower 
San Joaquin River, and the absence of scientifically supportable 
temperature standards on the San Joaquin and Sacramento Rivers to 
support the Fish Migration and Cold Fresh Water Habitat uses, including 
the fall-run and winter-run chinook salmon.
    In the summer of 1992, the State Board held hearings for the 
purpose of establishing interim measures to protect the natural 
resources in the Bay/Delta estuary. EPA participated in these 
hearings--rather than proposing federal standards at that time--in the 
hope that the hearings would result in state adoption of approvable 
standards and preclude the need for a federal rulemaking. EPA submitted 
its own recommendations to the State Board and joined with the National 
Marine Fisheries Service (NMFS) and the U.S. Fish and Wildlife Service 
(USFWS) in submitting an Interagency Statement of Principles. These 
statements specifically recommended that the State Board adopt a 
habitat and ecosystem-based approach to standards that would satisfy 
CWA requirements and meet the State Board's goal of reversing the 
decline of the estuary's fish and wildlife resources.
    At the conclusion of these hearings, the State Board, on December 
10, 1992, issued its recommended interim measures in Draft Water Rights 
Decision D-1630 (hereinafter D-1630). After the close of the comment 
period for D-1630, however, the State Board declined to adopt D-1630. 
Accordingly, the State criteria EPA disapproved on September 3, 1991, 
are still in effect. In response to the State Board's failure to revise 
these criteria, EPA, pursuant to section 303 (c)(3) and (c)(4) of the 
Act, published a Proposed Rule that would establish Federal water 
quality criteria for the Bay/Delta which would in effect supersede and 
supplement the disapproved State criteria for purposes of the CWA. 
EPA's Proposed Rule also satisfied its obligations under a partial 
settlement agreement approved and entered as an order in Golden Gate 
Audubon Society et al. v. Browner, (E.D. Ca. Civ. No. 93-646 (LKK)).
    EPA's Proposed Rule was one component of a coordinated initiative 
by the several Federal agencies having regulatory or operational 
responsibilities in the Bay/Delta. In early 1993, these four agencies--
EPA, USFWS, NMFS, and USBR--formed the Federal Environmental 
Directorate (now known almost exclusively as ``Club FED'') for the 
purpose of assuring that the Federal agencies worked in a coordinated 
manner in taking actions under their respective statutory authorities 
that would affect the estuary. The Federal initiative announced in 
December 1993 included the EPA Proposed Rule, the USFWS proposal to 
list the Sacramento splittail as a threatened species under the ESA, 
the USFWS proposal for critical habitat for the threatened Delta smelt, 
and the NMFS reclassification of the winter-run chinook salmon as 
endangered. This initiative also coincided with the USBR's preliminary 
water allocation forecast for CVP deliveries for the 1994 water year.
d. Post-Proposal Activities
    Since the publication of the Proposed Rule, EPA has moved towards 
final promulgation of protective criteria in an expeditious and open 
manner. EPA held several public hearings throughout the state in late 
February, 1994, to hear comments on the Proposed Rule. In addition, EPA 
met with a number of interested parties to discuss the economic 
analysis prepared in conjunction with the Proposed Rule. The purpose of 
these meetings was to solicit recommendations as to how to improve the 
analysis of potential economic impacts resulting from the State's 
implementation of the Federal criteria.
    EPA also participated in a series of scientific workshops arranged 
and facilitated by California Urban Water Agencies (CUWA), the Bay 
Institute, the Natural Heritage Institute, Save San Francisco Bay 
Association, and the Environmental Defense Fund. These workshops were 
designed to discuss the extensive scientific comments submitted by CUWA 
on the criteria proposed in the Proposed Rule. Dr. Wim Kimmerer, the 
reporter for these workshops, prepared written summaries of the 
discussions on the Estuarine [[Page 4667]] Habitat criteria and the 
Fish Migration Criteria (Kimmerer 1994b). As discussed above, the 
summary of the workshops on the Fish Migration criteria and EPA's 
alternative formulation of the Fish Migration criteria were made 
available to the public in EPA's Notice of Availability published on 
August 26, 1994, 59 FR 44095.
    The Federal interagency cooperation effort begun before the 
publication of the Proposed Rule has continued during the past year. 
The most formal aspects of this cooperation effort have been the 
consultations under Section 7 of the ESA between EPA and the USFWS and 
NMFS on the potential effects of EPA's criteria on threatened and 
endangered species and their critical habitat.\6\ EPA and the Services 
began consulting informally in December 1991. Formal consultations were 
initiated in August 1993. In recognition of the tentative nature of a 
proposed rule, the Services deferred preparing a formal biological 
opinion for the Proposed Rule and instead, on November 24, 1993, 
submitted formal comments to EPA on the Proposed Rule. These formal 
comments raised the major concerns of the respective Services about 
potential effects of the proposed criteria on threatened and endangered 
species. Since publication of the Proposed Rule, the Services have 
worked closely with EPA to assure that the final rule complies with the 
ESA. The Services have been actively involved in reviewing comments 
received from the public, and participated in the CUWA scientific 
workshops on EPA's Proposed Rule.

    \6\As stated above, the species of concern include primarily the 
winter-run chinook salmon (a listed endangered species under the 
jurisdiction of NMFS) and the Delta smelt (a listed threatened 
species under the jurisdiction of the USFWS). The USFWS has also 
formally proposed that the Sacramento splittail be listed as 
threatened.
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    In early November 1994, after discussing the probable final 
criteria with EPA, NMFS and USFWS concluded their reviews of the final 
criteria and issued their respective final conclusions as to the 
anticipated effects of the implementation of these criteria on 
threatened and endangered species. The USFWS issued a ``no jeopardy'' 
biological opinion under Section 7 of the ESA, finding that 
implementation of these criteria would not likely jeopardize the 
continued existence of any listed species or result in adverse 
modification of habitat deemed critical to the survival of listed 
species. In recognition of the fact that the final EPA criteria may be 
implemented only when the State Board adopts final implementation 
plans, the USFWS biological opinion also called for the reinitiation of 
consultations when the implementation plans are finalized by the State 
Board so that any possible problems for endangered or threatened 
species caused by implementing the criteria can be addressed.
    NMFS concluded its review by making a finding that implementation 
of these criteria would not adversely affect the threatened and 
endangered species or result in adverse modification of critical 
habitat of those species (anadromous fishes) under its jurisdiction. 
The NMFS findings also called for reinitiation of consultation when 
implementation plans are developed by the State Board, so that any 
possible problems for threatened or endangered species caused by 
implementing the criteria can be addressed.
    In addition to the formal ESA consultation process, the four Club 
Fed agencies have again coordinated several of their regulatory and 
operational duties and are announcing two Federal actions 
simultaneously. In addition to EPA's final promulgation of water 
quality criteria under the CWA, the USFWS is making it's final 
designation of critical habitat for the Delta smelt under the ESA. 
These coordinated Federal actions serve as the underlying basis for the 
long-term solution to fish and wildlife protection in the Bay/Delta 
estuary.
    Finally, in an effort to facilitate the long-term resolution of 
Bay/Delta issues, the Club Fed agencies and their counterpart agencies 
in the State of California executed, as of July 1994, a Framework 
Agreement laying out the Federal and State intentions as to how these 
agencies would work together cooperatively on a range of issues in the 
estuary. One key element of this Framework Agreement was EPA's 
agreement to sign a final rule regarding these water quality criteria 
by the end of 1994. At the same time, the State Board agreed to prepare 
a draft revision to its water quality plan by the end of 1994, and to 
finalize that plan in early 1995. The Framework Agreement envisions 
that, if EPA finds that the revised State plan submitted to EPA meets 
the requirements of the CWA, EPA will initiate action to withdraw this 
rule.
    Consistent with its commitment in the Framework Agreement, the 
State Board conducted a series of workshops on Bay/Delta issues 
throughout the spring, summer and fall of 1994. EPA participated in 
these workshops, and has continued to work with the State Board to 
assure that the revisions adopted by the State Board will meet the 
requirements of the CWA. It is EPA's hope that the cooperative process 
outlined in the Framework Agreement will lead to approvable state 
standards for protecting the designated uses in the Bay/Delta estuary.
    EPA is aware of efforts by urban and agricultural users, in 
cooperation with environmental groups, to identify alternative 
standards that may meet the requirements of the CWA. EPA encourages 
affected parties to continue to work with EPA and the State to develop 
proposals that meet the requirements of the CWA. EPA would welcome the 
adoption by the State of a revised plan based in whole or in part on 
such private proposals provided that it complies with the requirements 
of the CWA.

B. Statutory and Regulatory Background

    Section 303(c) of the Act requires that state water quality 
standards ``* * * be such as to protect the public health or welfare, 
enhance the quality of water and serve the purposes of this [Act]. Such 
standards shall be established taking into consideration their use and 
value for propagation of fish and wildlife, recreational purposes, and 
agricultural, industrial, and other purposes. * * *'' Key concerns of 
this statutory provision are the enhancement of water quality for the 
protection of the propagation of fish and other aquatic life. The 
ultimate purpose of water quality standards, as with the other 
provisions of the CWA, is ``to restore and maintain the chemical, 
physical, and biological integrity of the Nation's waters.'' CWA 
section 101(a).
    Under section 303(c) of the Act, a water quality standard for a 
specific waterbody consists of two components: designated uses for 
which a waterbody is to be protected (such as recreation in and on the 
water, protection and propagation of fish and wildlife, or agricultural 
uses) and the water quality criteria which support those designated 
uses.\7\

    \7\As discussed below, a state's water quality standards must 
also contain an antidegradation policy.
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    The Act gives primary responsibility for the adoption of water 
quality standards to the states. After adopting its initial water 
quality standards, a state is required, no less than every three years, 
to review those standards, and, if necessary, modify them. Under 
section 303(c)(1) of the Act, if a state revises or adopts a new 
standard, it must submit such a standard to EPA for approval or 
disapproval. [[Page 4668]] 
    EPA's Water Quality Standards regulations at 40 CFR part 131 
specify the requirements for designated uses. ``Designated Uses'' are 
those uses specified in water quality standards for each water body or 
segment whether or not they are being attained. 40 CFR 131.3(f). 
Examples of designated uses are listed in section 303(c)(2)(A) of the 
CWA. They include: public water supplies, protection and propagation of 
fish, shellfish, and wildlife, recreation, agricultural and industrial, 
and navigation. Other uses have been adopted as well (e.g. aquifer 
protection, coral reef preservation).
    Under certain circumstances, States may remove a designated use 
which is not an existing use. 40 CFR 131.10(g). ``Existing Uses'' are 
those uses actually attained in the water body on or after November 28, 
1975, whether or not they are included in the water quality standards. 
40 CFR 131.3(f). Generally, existing uses, whether or not they are 
``designated uses,'' may not be removed. 40 CFR 131.3(g) and (h). A 
state must conduct a ``use attainability analysis'' as defined in 40 
CFR 131.3(g) whenever (1) the State designates uses that do not include 
the uses specified in section 101(a)(2) of the CWA, or (2) the State 
wishes to remove a designated use that is specified in section 
101(a)(2) of the CWA or to adopt subcategories of uses which require 
less stringent criteria. 40 CFR 131.3(j). The state may take economics 
into account when it designates uses, as, for example, in a use 
attainability analysis. 40 CFR 131.3(g)(6).
    EPA's Water Quality Standards regulations at 40 CFR part 131 
specify the requirements for water quality criteria.

    States must adopt those water quality criteria that protect the 
designated use. Such criteria must be based on sound scientific 
rationale and must contain sufficient parameters or constituents to 
protect the designated use. For waters with multiple use 
designations, the criteria shall support the most sensitive use. 40 
CFR 131.11(a).

Thus, once designated uses are established, the water quality criteria 
are based on what is necessary scientifically to protect the most 
sensitive designated use.
    In addition, a state's criteria must be consistent with the state's 
antidegradation policy. The federal regulations provide that, at a 
minimum, the state must have an antidegradation policy that maintains 
``[e]xisting instream water uses [those existing in the waterbody at 
any time on or after November 28, 1975] and the level of water quality 
necessary to protect the existing uses. * * *'' 40 CFR 131.12(a)(1).
    In order to approve a state's water quality criteria, EPA must 
determine that the state has adopted ``water quality criteria [that 
are] sufficient to protect the designated uses.'' 40 CFR 131.6(c).
    Section 303(c)(4) of the Act provides that the Administrator shall 
promptly prepare and publish proposed regulations establishing a new or 
revised standard in either of two situations: first, when the 
Administrator has disapproved a state standard under section 303(c)(3) 
and the state has not taken corrective action within 90 days; and, 
second, in any case where the Administrator determines that a revised 
or new standard is necessary to meet the requirements of the Act. Once 
promulgated, the federal regulations are applicable to the state's 
waters, and, if they are more stringent, have the effect of supplanting 
and supplementing the state's standards for all purposes under the CWA. 
However, it is EPA's longstanding policy that the federal water quality 
standards will be withdrawn if a state adopts and submits standards 
that in the Agency's judgment meet the requirements of the Act.
    The chronology of State and EPA actions under the CWA in the Bay/
Delta estuary over the past two decades were described in more detail 
in the preamble to the Proposed Rule, and in paragraph A.1.c. herein. 
Briefly stated, the State Board's adoption of the 1978 Delta Plan, and 
of the revised Bay/Delta Plan in 1991, were intended to meet the 
State's obligations to establish water quality standards under the CWA. 
Pursuant to its mandate under section 303(c)(3) of the Act, on 
September 3, 1991, EPA disapproved several of the criteria contained in 
the State Board's plan. EPA's letter found that ``[t]he record * * * 
does not support the conclusion that the State has adopted criteria 
sufficient to protect the designated uses'' of the estuary. The 
designated uses at risk, as defined by the State Board, include 
Estuarine Habitat, and also Cold and Warm Water Habitat, Fish 
Migration, Fish Spawning, Ocean Commercial and Sport Fishing, 
Preservation of Rare and Endangered Species, Shellfish Harvesting, and 
Wildlife Habitat. In addition to its general finding that the 1991 Bay/
Delta Plan did not contain sufficient criteria to protect the 
designated uses, EPA also disapproved the absence of salinity criteria 
to protect fish and wildlife uses in the Suisun, San Pablo, and San 
Francisco Bays and Suisun Marsh, the absence of scientifically 
supportable salinity criteria (measured by electrical conductivity) to 
protect the Fish Spawning uses of the lower San Joaquin River, and the 
absence of scientifically supportable temperature standards on the San 
Joaquin and Sacramento Rivers to protect the Fish Migration and Cold 
Fresh Water Habitat Uses.
    For the reasons outlined herein, in the Proposed Rule, and in EPA's 
letter of September 3, 1991, the Agency finds that the water quality 
criteria adopted by the State fail to protect the designated uses and 
that the criteria below meet the requirements of the Act. Accordingly, 
pursuant to sections 303(c)(3) and 303(c)(4) of the Act, the 
Administrator is promulgating the following water quality criteria 
applicable to the Bay/Delta's waters.

C. Description of the Final Rule and Changes From Proposal

1. Estuarine Habitat Criteria

a. Overview
    (1) Importance of the Estuarine Habitat Designated Use. The State's 
1991 Bay/Delta Plan included ``Estuarine Habitat'' as a designated use 
for the Bay/Delta estuary. This Estuarine Habitat designated use is 
intended to provide ``an essential and unique habitat that serves to 
acclimate anadromous fishes (salmon, striped bass) migrating into fresh 
or marine conditions. This habitat also provides for the propagation 
and sustenance of a variety of fish and shellfish, numerous waterfowl 
and shore birds, and marine mammals.'' See Water Quality Control Plan, 
San Francisco Bay Basin [2], December 1986, at II-4.
    EPA considers protection of the Estuarine Habitat designated use to 
be important for a number of important reasons. As described in detail 
in the Preamble to the Proposed Rule, conditions in the estuary are of 
critical importance because the estuary's particular characteristics 
provide a unique food source, spawning habitat or nursery habitat for a 
whole range of aquatic and aquatic-dependent species. The Estuarine 
Habitat designated use protects this vital ecosystem, an ecosystem that 
has a crucial role in restoring and protecting the fish and wildlife 
populations of the Bay/Delta. EPA and the other Federal agencies are 
committed to multispecies or ecosystem protection approaches, rather 
than focusing on the peculiar needs of individual species. In addition, 
the resource values benefitting from the protection of the Estuarine 
Habitat use include resources described in other state-designated uses, 
including Ocean Commercial and Sport Fishing, Preservation of Rare and 
Endangered Species, Fish Migration, and Wildlife 
[[Page 4669]] Habitat.\8\ Indeed, many of the resources targeted for 
protection by these related uses would not be fully protected without 
adequate protection of the Estuarine Habitat designated use. In 
developing criteria protective of the Estuarine Habitat use, EPA has 
been mindful of the overlapping designated uses and of the range of 
natural resources affected by the broad Estuarine Habitat.

    \8\As described by the State Board, the Ocean Commercial and 
Sport Fishing designated use protects the ``commercial fishing and 
collection of various types of fish and shellfish, including those 
taken for bait purposes, and sport fishing in ocean, bays, estuaries 
and similar non-freshwater areas.'' The Preservation of Rare and 
Endangered Species use ``[p]rovides an aquatic habitat necessary, at 
least in part, for the survival of certain species established as 
being rare and endangered species.'' As described below, the Fish 
Migration use ``[p]rovides a migration route and temporary aquatic 
environment for anadromous or other fish species.'' Finally, the 
Wildlife Habitat ``[p]rovides a water supply and vegetative habitat 
for the maintenance of wildlife.''
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BILLING CODE 6560-50-P
                                                                       
    [[Page 4670]]
    
[GRAPHIC][TIFF OMITTED]TR24JA95.000



BILLING CODE 6560-50-C [[Page 4671]] 
    (2) Proposed Criteria. As stated in the Proposed Rule, the 
Estuarine Habitat criteria consisted of three interrelated components:
    (i) A salinity requirement of 2 parts per thousand (2 ppt);
    (ii) Maintained at one or more of three monitoring locations in the 
Suisun Bay;
    (iii) For a specified number of days during the critical spring 
months.

These criteria were designed to reflect the conditions in the estuary 
at a time when it attained protection of the designated Estuarine 
Habitat use.
    As a preliminary matter, EPA determined the ``reference period,'' 
the historical time period during which the salinity regime in the 
estuary was sufficient to protect the designated uses. To determine the 
reference period, EPA was guided by the Interagency Statement of 
Principles signed by EPA, USFWS and NMFS, which called for estuarine 
conditions similar to the late 1960's to early 1970's as necessary to 
protect the Estuarine Habitat. However, the decade from 1965 to 1974 
did not include water years types from each of the five water year type 
categories.\9\ Therefore, in order to estimate those conditions over 
the entire range of possible hydrological conditions that may occur in 
the future, EPA used data from the years 1940 to 1975 to represent the 
conditions in the reference period of the late 1960's to early 1970's, 
and used this larger set of historical data to determine the minimum 
number of days of compliance.

    \9\``Water year'' type categories in California refer to 
precipitation patterns for the year. The standard water year 
categories are wet, above normal, below normal, dry, and critically 
dry years.
---------------------------------------------------------------------------

    As explained in more detail below and in the preamble to the 
Proposed Rule, EPA then focused on the salinity regime in the estuary 
to develop criteria that protect the Estuarine Habitat. Salinity was 
selected for several reasons: it is closely associated with the 
abundance and distribution of species at all trophic levels, it can be 
measured accurately and easily, and it integrates a number of important 
estuarine properties and processes.
    Salinity conditions in the estuary vary dramatically from month to 
month and year to year, primarily in response to natural factors such 
as precipitation and snowmelt upstream, and to man-made factors such as 
reservoir operations, upstream diversions and export rates. EPA 
concluded that maintaining salinity conditions reflecting the natural 
hydrology in the Bay/Delta during the reference period would provide 
estuarine habitat conditions that protect the fish and wildlife 
resources dependent on that habitat. In other words, because 
precipitation varies naturally from year to year and within each year, 
salinity conditions reflecting this natural variability at a time 
period when the Bay/Delta attained its designated uses would protect 
the natural resources dependent upon estuarine habitat. While it may 
seem counterintuitive to provide less fresh water to the estuary in a 
dry year, and more water in a wet year, the natural resources in the 
Bay/Delta ecosystem have adapted to the cycle of both within-year 
hydrological fluctuations and substantial year-to-year fluctuations in 
hydrology. The intent of the proposed criteria was to restore a pattern 
and magnitude of those hydrological fluctuations that reflected the 
historical period during which the designated uses were fully 
protected.
    To provide these conditions, EPA proposed maintaining the low 
salinity\10\ 2 ppt isohaline (an isohaline is simply a line joining all 
points of equal salinity) in Suisun Bay during the critical wet season 
months of February to June. This particular time period is important 
because many different species use the low salinity habitat in the 
spring for spawning, as nursery habitat, for transportation through the 
Delta, or for a combination of these three purposes. To take account of 
the variation in natural hydrological conditions, EPA proposed criteria 
that varied according to the water year type. In all water years, the 2 
ppt salinity criteria would be met at the furthest upstream monitoring 
site (the confluence of the Sacramento and San Joaquin Rivers at the 
upstream end of Suisun Bay). In wetter years, the 2 ppt salinity 
criteria would also be met at one or both of two downstream monitoring 
sites (Chipps Island and Roe Island, in the middle and downstream end 
of Suisun Bay, respectively).

    \10\Low salinity in the 2 ppt range is being used to describe 
salinity conditions in the ``mixing zone'' between freshwater coming 
downstream and marine water moving inland from the ocean in response 
to tidal influences and fluctuations in freshwater outflow. This 
mixing zone generally contains low surface salinity of 1 to 6 ppt, 
whereas ocean salinity is over 30 ppt and freshwater salinity is 
generally less than 1 ppt (Arthur and Ball 1979).
---------------------------------------------------------------------------

    The proposal was stated as requiring attainment of the 2 ppt 
salinity criteria at or below one of the three monitoring sites for a 
specified number of days during the February to June period, depending 
on the water year type. For example, under the Proposed Rule, in a 
``below normal'' water year, the 2 ppt isohaline would have been 
required at or downstream of Chipps Island for a total of 119 days 
during the February to June period. This ``number of days'' approach 
allowed the criteria to be responsive and replicative of the varying 
natural hydrology during February to June. That is, if February or 
March were particularly wet, the criteria's ``number of days'' could be 
met at that time using those natural storm flows, rather than requiring 
reservoir releases later in the February to June period.
    Finally, again in an attempt to match the criteria with the natural 
hydrology, the Proposed Criteria included a ``trigger'' for compliance 
with the farthest downstream monitoring site (Roe Island). Compliance 
at that site would not be required unless and until the 2 ppt isohaline 
had been pushed that far downstream through natural storm events.
    (3) Final Criteria. The Estuarine Habitat criteria in the final 
rule have been revised to address many of the technical issues raised 
in the public comments. The fundamental structure of the Estuarine 
Habitat criteria is unchanged: The criteria require maintenance of the 
2 ppt\11\ isohaline at or downstream of one of three monitoring sites 
in Suisun Bay during a specified portion of the February through June 
period. The final criteria continue to require a 2 ppt salinity value 
at the Confluence of the Sacramento and San Joaquin rivers each day 
between February through June in all years. The 2 ppt salinity value is 
to be met at Chipps Island for a specified number of days, depending on 
the amount of precipitation. The greater the precipitation, the higher 
the number of days the criteria must be attained. The 2 ppt salinity 
value must be met at Roe Island only if it is triggered by 
precipitation sufficient to push the 2 ppt salinity value downstream to 
Roe Island during the last half of the previous month. Once triggered, 
the 2 ppt salinity value is to be met at Roe Island for a specified 
number of days, depending on precipitation.

    \11\The Proposed Rule stated the criteria as a requirement for 2 
ppt salinity. As discussed more fully below, in order to state the 
requirement more precisely, the final rule language will define the 
criteria in terms of micromhos per centimeter specific conductance 
at 25  deg.C instead of parts per thousand salinity. Accordingly, 
the final rule will state the criteria value as ``2640 micromhos/
cm,'' which is equivalent to 2 ppt salinity. Although EPA is 
restating the actual rule language in the more precise specific 
conductance language, it will continue to refer to this criteria 
value as 2 ppt in this discussion of the final rule.
---------------------------------------------------------------------------

    The changes to the final criteria are primarily refinements to how 
the rule determines the number of days the salinity standard must be 
met at Chipps and Roe Islands. The primary revisions include:
    (i) Shift from water year categories to a ``sliding scale''. Rather 
than basing the number of days on data reflecting average salinity for 
each of the five water year types, EPA is basing the number of days on 
a ``sliding scale'' or ``smooth function'' that more precisely states 
the correlation between precipitation and the number of days of the 2 
ppt value. For example, whereas the previous approach would require the 
same number of days of the 2 ppt value for all ``above normal'' years, 
the sliding scale requires fewer number of days for a dry ``above 
normal'' year than for a wet ``above normal'' year. In other words, 
rather than stating the criteria as five discrete points representing 
water year types, the sliding scale uses all the data underlying those 
five points to construct a continuous function or line reflecting 
salinity as a function of flow. The sliding scale is a more realistic 
description of the relationship between salinity and flow as it existed 
at the time during which the estuary attained its designated uses.
    (ii) Shift from yearly hydrology to monthly hydrology. Instead of 
basing the number of compliance days at Chipps and Roe Islands on the 
expected hydrological conditions for the entire year, the final 
criteria base the current month's requirements only on the previous 
month's hydrological conditions. This change requires that these 
criteria specify a ``sliding scale'' for each month, but allows a much 
more accurate reflection of variations in natural hydrology.
    (iii) Revising the data used to reflect more accurately conditions 
in the estuary during the reference period. As explained above, the 
reference period is the historical time period when the estuary 
attained its designated uses. In the Proposed Rule, EPA used the late 
1960's to early 1970's as the reference period because the available 
information about the fish and wildlife resources in the Bay/Delta 
suggests that this time period encompasses the most recent time period 
during which the designated uses were attained. To describe 
hydrological and salinity conditions in this late 1960's to early 
1970's reference period, the Proposed Rule used data from 1940 to 1975. 
This longer period was used because the actual conditions in the late 
1960's to early 1970's did not provide representative samples of the 
possible broad range of hydrological conditions in the estuary. The 
Proposed Rule suggested that the period 1940-1975 could be considered 
representative of the late 1960's to early 1970's because the longer 
period was one of fairly consistent hydrological conditions bracketed 
by the completion of Shasta Dam on the Sacramento in the early 1940's 
and by the severe drought of the mid-1970's.
    EPA received much comment on the approach in the Proposed Rule, 
with some commenters arguing convincingly that the 1940 to 1975 was in 
fact not one of consistent hydrological conditions, since the ``level 
of development''--the change in the facilities used for water diversion 
and storage--changed over time during this period due to additional 
construction activities at the state, federal, and local levels. EPA 
agrees with these comments and has reevaluated the historical data to 
account for the effects of the level of development on the salinity 
regime in Suisun Bay. As discussed below, EPA has determined that it is 
appropriate to use the level of development--and corresponding salinity 
regime--represented by calendar year 1968 as a surrogate for the late 
1960's to early 1970's reference period when the estuary attained its 
designated uses.
    (iv) Alternative measures of attainment. Under the CWA, the State 
Board has the responsibility for developing an implementation plan, 
including the methodology for measuring attainment. Based on the 
comments received as discussed below, EPA believes that attainment 
could be measured at the Roe Island and Chipps Island monitoring sites 
by any of (1) the daily salinity value, (2) the 14-day average 
salinity, or (3) the ``flow equivalence'' of the salinity value, as 
predicted in the recent Contra Costa Water District (CCWD) model 
described below. For reasons that are peculiar to that model, 
attainment at the Confluence monitoring site could be measured by 
either of the first two of these approaches only.
b. Detailed Discussion
(1) Proposed Estuarine Habitat Criteria
    The Estuarine Habitat criteria included in the Proposed Rule 
specified the location and number of days that the 2 ppt salinity value 
would need to be met to protect the designated use. EPA's proposed 
criteria are shown in Table 1. They consisted of 2 ppt salinity 
criteria12 to be attained for a specified number of days at Roe 
Island, Chipps Island, and at the Sacramento/San Joaquin River 
confluence during the period of February through June. The Proposed 
Rule provided that the 2 ppt salinity value must be met at the 
Sacramento/San Joaquin River confluence monitoring station for the 
entire 150 day period from February through June. The number of days of 
compliance with the 2 ppt value at Chipps and Roe Islands were based on 
the late 1960's to early 1970's ``reference period'' representing a 
time in which the conditions in the estuary were adequate to protect 
the designated uses. To represent this reference period, the criteria 
replicated the average number of days in each of the five water year 
types during which the 2 ppt salinity value occurred at or downstream 
from each of these locations during the historical period 1940-1975. 
Because no critically dry years occurred in the period from 1940 to 
1975, the required number of days for critically dry years was based on 
an extrapolation of the data. In addition, in a number of years in the 
1940-1975 period, data existed for flow conditions in the estuary but 
not for salinity. For these years, the Kimmerer-Monismith model (SFEP 
1993) was used to estimate the salinity regime based on the existing 
flow data. [[Page 4672]] 

    \12\EPA's proposed Estuarine Habitat criteria were stated as a 
certain number of days when the average daily near-bottom salinity 
at each of three locations in the estuary is less than 2 parts per 
thousand. This salinity is approximately equivalent to electrical 
conductivity less than 2.640 mmhos/cm EC when corrected to a 
temperature of 25 deg.C.
---------------------------------------------------------------------------

    The proposed criteria were to be measured using a 14-day moving 
average.13 The use of a 14-day moving average allowed the mean 
location to be achieved despite the varying strength of tidal currents 
during the lunar cycle, because any 14 day period would include the 
full range of spring and neap tidal conditions.14

    \13\A 14 day moving average would compute the salinity for a 
given day by taking the overall average of daily averages of 
salinity values for the measurement day and each of the previous 13 
days. At the monitoring sites used in the Estuarine Habitat 
criteria, salinity is generally measured at least hourly, thereby 
facilitating computation of daily averages.
    \14\Spring and neap tides refer to the times during the 28 day 
lunar cycle when tides are strongest and weakest, respectively.

                                                                                                                
[[Page 4673]]                                                                                                   
         Table 1.--Proposed 2 ppt Estuarine Habitat Criteria\1\         
------------------------------------------------------------------------
                                        Chipps Island [km    Confluence 
     Year type      Roe Island [km 64]         74]            [km 81]   
------------------------------------------------------------------------
Wet...............  133 days..........  148 days.........  150 days.    
Above normal......  105 days..........  144 days.........  150 days.    
Below normal......  78 days...........  119 days.........  150 days.    
Dry...............  33 days...........  116 days.........  150 days.    
Critically dry....  0 days............  90 days..........  150 days.    
------------------------------------------------------------------------
\1\Numbers indicate the required number of days (based on a 14-day      
  moving average) at or downstream from each location for the 5-month   
  period from February through June. The water year classifications are 
  identical to those included in the 1991 Bay/Delta Plan for the        
  Sacramento River Basin. Roe Island salinity shall be measured at the  
  salinity measuring station maintained by the USBR at Port Chicago (km 
  64). Chipps Island salinity shall be measured at the Mallard Slough   
  station, and salinity at the Confluence shall be measured at the      
  Collinsville station, both of which are maintained by the California  
  Department of Water Resources. The Roe Island number represents the   
  maximum number of days of compliance, based on the adjustment         
  described in the text.                                                

    As explained in more detail in the Proposed Rule, the proposed 
Estuarine Habitat criteria also included a ``trigger'' that limited the 
applicability of the Roe Island criteria to wetter years. This trigger 
provided that the Roe Island criteria would not apply in a particular 
year unless and until the average daily salinity at Roe Island attained 
the 2 ppt level through natural uncontrolled flows. If that occurred, 
the 2 ppt salinity value would have to be met at Roe Island for the 
number of days specified in Table 1 (or the number of days left in the 
February to June period, if that number was less). In effect, this 
``trigger'' provided that the additional water needed to move the 2 ppt 
isohaline downstream to Roe Island would come from natural storms 
rather than from reservoir releases or export restrictions. This 
approach helped the criteria reproduce the natural variability in 
timing and quantity of runoff that existed during the reference period.
    In the Proposed Rule, EPA requested public comment on a number of 
issues, including the desirability of stating the criteria as a 
``sliding scale'' rather than by water year categories, the appropriate 
compliance measurement period, and the appropriate reference period for 
criteria target levels. EPA has incorporated many of the comments 
received on these and other issues in its revisions to the Proposed 
Rule.
(2) Technical Changes to the Estuarine Habitat Criteria
    The fundamental structure of the Estuarine Habitat criteria in the 
final rule is unchanged from the Proposed Rule: The criteria require 
maintenance of the 2 ppt isohaline at or downstream of one of three 
monitoring sites in Suisun Bay during a specified portion of the 
February through June period. The final criteria continue to require a 
2 ppt salinity value at the Confluence of the Sacramento and San 
Joaquin rivers each day between February through June in all years.
    Virtually all of the changes to the final Estuarine Habitat 
criteria involve refinements for determining the number of days the 
salinity standard must be met at Chipps and Roe Islands. In general, 
these changes either make certain measurements more accurate or provide 
a closer approximation of the natural hydrological cycles. The changes, 
which are highly technical, can be grouped into four broad categories: 
(i) underlying computational revisions, (ii) using a sliding scale, 
(iii) using monthly rather than annual compliance, and (iv) alternative 
measurement of attainment of the criteria. These changes to the final 
rule are reflected in the final criteria at 40 CFR 131.37(a)(1).
    (i) Underlying Computational Revisions.
    The first group of changes in the final criteria are slight 
refinements to the methodology of some of the computations used in the 
rule. These include:
    (I) Updated model correlating salinity and flows. As described 
above, the Proposed Rule used data from the historical period 1940 to 
1975 to approximate conditions in the targeted late 1960's to early 
1970's reference period. For years during that historical period when 
actual salinity data was unavailable, the Proposed Rule used the 
Kimmerer-Monismith model to estimate salinity conditions based on the 
available flow data. This earlier model, which was used by the San 
Francisco Estuary Project (SFEP) (SFEP 1993), was considered at that 
time to be the most accurate available for this purpose. Since the 
Proposed Rule was published, a revised model correlating salinity and 
flow has been developed by the CCWD (Denton, R.A. 1993, and Denton, 
R.A. 1994). EPA concluded, and the participants at the CUWA scientific 
workshops generally agreed (Kimmerer 1994b), that the CCWD model is a 
more appropriate model to use in developing the Estuarine Habitat 
criteria.15 The final rule will use this new CCWD model to 
estimate the number of days that salinities have been less than 2 ppt 
historically at each of the compliance monitoring stations.

    \15\The CCWD model developed by Denton and Sullivan models 
salinity at a particular location, whereas the Kimmerer-Monismith 
model models the location of a particular salinity. Thus, the 
Kimmerer-Monismith model can predict whether the 2 ppt salinity 
value is upstream or downstream of a given location whereas the CCWD 
model can predict if the salinity at the same point is greater or 
lesser than 2 ppt. The CCWD model is more accurate because it 
predicts salinity based not only on flow (as in the Kimmerer-
Monismith model) but also based on the location being modeled. For 
example, the relationship between flow and salinity is slightly 
different at Roe Island than at the Confluence, and only the CCWD 
model reflects that difference in the relationship.
---------------------------------------------------------------------------

    The earlier model used for the Proposed Rule measured salinity one 
meter above the bottom. The new CCWD model measures salinity measured 
at the surface. There is substantial evidence that at salinities near 2 
ppt there is little variability in stratification so that bottom 
salinities are accurately predicted from surface salinities (CCWD 1994; 
Monismith 1993). Therefore, bottom salinities of 2 ppt as modeled by 
the Kimmerer-Monismith model correspond to surface conductivities 
described, as discussed below, in terms of electroconductivity of 2.640 
mmhos/cm EC in the CCWD model.
    (II) Use of entire basin unimpaired flow. In calculating the 
applicable Estuarine Habitat criteria value, the Proposed Rule measured 
flow by reference to the Sacramento Basin Water Year Type 
classification. EPA did this primarily to simplify calculations and to 
reflect the dominant role of Sacramento River flows in the Bay/Delta 
estuary.16 Nevertheless, as commenters noted, in some 
circumstances the omission of the San Joaquin River basin flows from 
the calculation could significantly overstate [[Page 4674]] or 
understate the actual hydrological conditions in the estuary because 
precipitation patterns in the two river basins are not identical. 
Further, one of the reasons EPA chose the three locations for 
compliance (all at or downstream of the confluence of the Sacramento 
and San Joaquin Rivers) was to give the State Board maximum flexibility 
in determining the source of flows to meet the Estuarine Habitat 
criteria. To reflect the importance of the San Joaquin River basin, the 
final criteria have been revised to measure unimpaired flow by 
reference to both the Sacramento River basin (Sacramento, Feather, 
Yuba, and American rivers) and the San Joaquin River basin (Stanislaus, 
Tuolumne, Merced, and San Joaquin rivers). EPA believes that the 
Sacramento/San Joaquin Unimpaired Flow Index described by CUWA is the 
best statement of how this unimpaired flow should be computed, and will 
generally refer to this index as the ``8-River Index.''17

    \16\The Sacramento River basin usually accounts for about 80% of 
net Delta outflow, with the remainder coming primarily from the San 
Joaquin River basin.
    \17\As stated on page 3 of Appendix 1 to the California Urban 
Water Agencies ``Recommendations to the State Water Resources 
Control Board for a Coordinated Estuarine Protection Program for the 
San Francisco Bay-Sacramento and San Joaquin River Delta Estuary'' 
dated August 25, 1994, the Sacramento/San Joaquin Unimpaired Flow 
Index ``shall be computed as the sum of flows at the following 
stations:
    1. Sacramento River at Band Bridge, near Red Bluff
    2. Feather River, total inflow to Oroville Reservoir
    3. Yuba River at Smartville
    4. American River, total inflow to Folsom Reservoir
    5. Stanislaus River, total inflow to New Melones Reservoir
    6. Tuolumne River, total inflow to Don Pedro Reservoir
    7. Merced River, total inflow to Exchequer Reservoir
    8. San Joaquin River, total inflow to Millerton Lake.''
---------------------------------------------------------------------------

    (III) ``Parts per thousand'' versus ``electroconductivity''. The 
Proposed Rule stated the criteria as a requirement for 2 ppt salinity 
at the three compliance stations for varying numbers of days. In order 
to state the requirement more precisely, the final rule language will 
define the criteria in terms of millimhos per centimeter 
electroconductivity or ``mmhos/cm EC'' instead of parts per thousand 
salinity. This change is being made to conform the final rule to the 
more traditional methodology for measuring fresh water salinity. 
Accordingly, the final rule will state the criteria value as ``2.640 
mmhos/cm EC,'' which is equivalent to 2 ppt salinity.
    Although EPA is restating the actual rule language in the more 
precise electroconductivity language, it will continue to refer to this 
criteria value as 2 ppt in this discussion of the final rule. To do 
otherwise would unnecessarily confuse the interested scientific and 
policy community, which for a number of years has been using the 2 ppt 
language in its discussion of estuarine habitat criteria.
    These revisions to the underlying computational methodology apply 
to the Estuarine Habitat at all three monitoring sites (the Confluence, 
Chipps, and Roe Islands). The remaining revisions to the final criteria 
pertain primarily to the methodology used in defining the number of 
days of compliance to be met at Chipps and Roe Islands.
    (ii) Using a Sliding Scale.
    In the final Estuarine Habitat criteria, EPA is restating the 
number of days that the 2 ppt salinity value must be met as a sliding 
scale correlating the number of days of compliance with unimpaired 
flow. The sliding scale approach has also been called the ``continuous 
function'' or ``smooth function'' approach. This approach replaces the 
Proposed Rule's statement of the criteria as a single fixed number of 
days of compliance for each of the five water year categories. The 
previous approach did not account for the substantial differences in 
hydrological conditions within water year types. For example, an 
``above normal'' water year type could range from a wet ``above 
normal'' year to a dry ``above normal'' year. Given the extreme 
variation of hydrological conditions in the Bay/Delta, these variations 
within each of the five standard water years types are substantial, and 
should be factored into the calculation of the number of days of 
compliance with the 2 ppt salinity criteria.
    The sliding scale approach addresses this problem by transforming 
the average salinity values for the five discrete water year categories 
into a more precise equation (graphically, a single line or curve) 
correlating the number of days of compliance with the specific observed 
hydrological conditions. This sliding scale approach would result in 
the same average number of days of compliance for each year type, and 
therefore represents the same level of protection for the Estuarine 
Habitat use as the Proposed Rule. The new approach, however, more 
accurately reflects differences within water year categories, thereby 
allowing a more accurate reflection of the natural hydrological cycles 
representative of the reference period necessary for protection of the 
use.
    In addition, while the sliding scale approach equally represents 
the conditions under which the estuary attains its designated uses, the 
sliding scale results in lower water costs and, for operational 
reasons, may actually enhance protection of the uses. Testimony at 
recent State Board hearings criticized the use of water year type 
categories. Because water year types can change as the year progresses, 
criteria based on the historical mean for each water year type can 
cause major changes in project operations and habitat conditions if a 
given year shifts from one water year type to another over the course 
of the winter months. For example, a later season storm could cause the 
water year type to be reclassified from the below normal category to 
the above normal category. This shift would increase the number of days 
the criteria must be met at one of the monitoring sites. Such large and 
sudden changes are inefficient for water resource management and may 
harm aquatic resources by dewatering or washing away newly spawned 
eggs. Incorporating a sliding scale definition of the criteria would 
likely ease the actual operational procedures necessary to meet the 
criteria and would avoid the relatively sudden, large scale changes in 
operations that might come from a sudden shift in the determination of 
year type as spring progresses.
    The comments EPA received on the Proposed Rule were generally 
supportive of this change in approach (CUWA 1994a, California DWR 1994, 
NHI 1994, and Kimmerer 1994a). Both written comments and the 
discussions at the CUWA scientific workshops offered several 
suggestions as to how the sliding scale function should be formulated.
    There are two major components to the sliding scale approach. 
First, the shape of the scale must be determined. Second, the actual 
scaled values must be determined.
    (I) Defining the sliding scale. There are a number of possible 
mathematical definitions of a sliding scale, including (a) a straight 
line, (b) a quadratic equation, or (c) a logistic equation.18

    \18\The standard forms of these types of equations are (a) a 
straight line (y=a+b*x), (b) a quadratic equation (y=a+b*x+c*x2) or 
(c) a logistic equation (y=1/(1+e3(a+b*x)).
---------------------------------------------------------------------------

    In the Proposed Rule, EPA suggested that a quadratic equation could 
be used to define the sliding scale. After reviewing the public 
comments, EPA has concluded that the Estuarine Habitat criteria should 
be stated as a logistic equation defining the sliding scale. Dr. Wim 
Kimmerer, in his comments on the Proposed Rule (Kimmerer 1994a), noted 
that the logistic model is ``appropriate [[Page 4675]] for a 
relationship between a dichotomous variable (i.e. compliance or no 
compliance) and a continuous variable.'' A logistic model cannot 
require fewer than 0 or more than the number of days available in the 
month, whereas linear equations (such as one included in written 
comments of CCWD (CCWD 1994) or quadratic equations (such as the one 
EPA suggested in the Proposed Rule) can result in unrealistic 
extrapolations (e.g., resulting in the criteria having to be met less 
than zero days or more than the number of possible days each 
month).19

    \19\While uncommon in some fields, the logistic equation is the 
basis of many ecological models, especially for population dynamics 
and epidemiology. In these ecological applications, the logistic 
model is useful because of the nature of the dichotomous variables 
(such as how many individuals are alive or dead in population 
dynamics, or how many individuals are infected or healthy in 
epidemiological studies). In each case, the dichotomous variables 
are arrayed along time as the continuous variable. In both cases, 
also, the function is constrained between 0 and the total population 
size, which is biologically realistic. EPA is using the logistic 
equation to model the number of days of attainment of the 2 ppt 
value (the dichotomous variable) against unimpaired flow (as the 
continuous variable). The logistic model also provides that no less 
than 0 and no more than the total number of days in the month can be 
required for attainment.
---------------------------------------------------------------------------

    Kimmerer suggested a sliding scale based on logistic equations that 
stated the percentage number of days of compliance during the February 
to June period as a function of the unimpaired flow for those five 
months. An example of graphic representations of these equations for 
Roe Island is shown in Figure 1. EPA has adopted this basic approach; 
however, as discussed below, EPA has revised the logistic equations to 
reflect monthly computations of compliance.

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    (II) Selecting sliding scale values: the reference period that 
would reflect protection of the designated uses. Having concluded that 
the logistic equation is the best form of sliding scale for the 
Estuarine Habitat criteria, EPA still needed to determine the 
appropriate reference period reflected in that logistic equation.
    In the Proposed Rule, EPA chose as the reference period the late 
1960's to early 1970's. Available information suggested that during 
this period the estuarine conditions were able to support the 
designated uses. To describe the conditions in this late 1960's to 
early 1970's reference period, the Proposed Rule used hydrological and 
salinity data from 1940 to 1975. This longer period was used because 
the actual conditions in the late 1960's to early 1970's did not 
provide representative samples of the possible broad range of 
precipitation conditions in the estuary.20 The Proposed Rule 
suggested that the period 1940-1975 could be considered representative 
of the late 1960's to early 1970's because the longer period was one of 
fairly consistent hydrological conditions bracketed by the completion 
of Shasta Dam on the Sacramento in the early 1940's and by the severe 
drought of the mid-1970's.

    \20\In fact, no dry or critically dry years, and only one above 
normal year occurred during the late 1960's to early 1970's.
---------------------------------------------------------------------------

    EPA received substantial comment about its choice of an historical 
reference period to define the targeted level of protection for the 
Estuarine Habitat criteria. One group of comments criticized the choice 
of the years included in the reference period. Various other historical 
periods were discussed by different commenters as alternatives. (Bay 
Institute 1994, California DWR 1994, and NHI 1994). EPA's specific 
responses to these comments are in the comment response document 
included in the record to this rule.
    A second set of comments raised a more fundamental problem with the 
use of an historical reference period. These comments argued that the 
choice of any particular historical reference period was inherently 
suspect if it could not account for the changing ``level of 
development'' (that is, the changing system of dams, diversion 
facilities, storage reservoirs, etc.) during the 1940 to 1970 period 
(California DWR 1994). For example, if exactly the same amount of 
precipitation had fallen in each of 1940 and 1970, the different 
``level of development'' in each year would affect how much water 
actually made its way down the rivers into Suisun Bay. In other words, 
the level of development, independent of the amount of rainfall, would 
affect the number of days that the 2 ppt salinity value was attained in 
Suisun Bay. Without accounting for the level of development, it would 
be hard to use rainfall data from the 1940's to represent conditions in 
the late 1960's to early 1970's.
    EPA is persuaded that addressing these concerns about the effects 
of the level of development on resulting salinity criteria is, to a 
certain extent, appropriate. EPA and others (notably, the CUWA 
scientific workshops) have presented and discussed methods for 
accounting for the level of development. The Final Rule includes a 
straightforward approach to this issue. Standard statistical regression 
analysis was used to isolate the effects on the number of days of 2 ppt 
salinity of (1) the level of development, represented by calendar 
year,21 and (2) precipitation (Kimmerer 1994b; Ferreira and Meyer 
1994). This statistical procedure allowed EPA to separate the effects 
of year-to-year variability in precipitation from the effects of 
increased levels of upstream development.22

    \21\The use of the calendar year as a surrogate for the level of 
development is reasonable up until the late 1970's, because up until 
that time there was a fairly consistent increase year-by-year in the 
number and capacity of diversion and storage facilities, and the 
significant changes to the salinity regime imposed by the 1978 Delta 
Plan had not yet taken effect. [[Page 4677]] 
    \22\In that this statistical procedure allowed the effect of the 
changing level of development to be controlled, the issue of the 
proper data set (i.e., group of reference years) to be included in 
the description of historical hydrological conditions essentially 
disappears. To take advantage of all appropriate historical data, in 
performing these computations EPA used data from the years 1930 
(when accurate records were first available) to 1978 (when the 
hydrological conditions in the Delta were first substantially 
affected by the regulatory measures adopted by the State Board).
---------------------------------------------------------------------------

    The results of these recomputations are shown graphically in 
Figures 1 and 2. The response surface or curved plane in Figure 2 shows 
how the number of days of 2 ppt salinity at Roe Island changes with 
both the precipitation (flow) and the changing level of development 
over time. Figure 1 shows several ``slices'' of the curved plane in 
Figure 2. Each of these different slices corresponds to a particular 
year's level of development (1940, 1958, 1968, and 1975), and show how 
the number of 2 ppt days would have varied over different hydrological 
conditions at that year's level of development. Historically, of 
course, each year experienced only one hydrological scenario; the 
purpose of the regression equations for these four different years is 
to show how that particular level of development would have influenced 
the position of the 2 ppt isohaline over the entire range of possible 
hydrological conditions.

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BILLING CODE 6560-50-C
    Having adjusted the historical data to account for the effects of 
the level of development, EPA must still determine the appropriate 
reference period for defining the final criteria. The final criteria 
must adequately reflect conditions in the estuary at a time period 
during which the estuary attained the designated uses, regardless of 
the causes of degradation to the waterbody.
    In the final rule, EPA is establishing Estuarine Habitat criteria 
that replicate the ``level of development'' existing in 1968. The 
intent of these criteria is to protect the Estuarine Habitat designated 
use to the same degree that these uses would have been protected under 
the level of development present in 1968.
    EPA chose the 1968 level of development because the best available 
information indicates that at that time, salinity conditions in the 
Bay/Delta were adequate to protect the estuarine habitat. As explained 
in the Proposed Rule, EPA, NMFS, and USFWS have called for a level of 
protection equal to that which existed in the late 1960's and early 
1970's. EPA believes that the fish population data summarized in the 
San Francisco Estuary Project's Status and Trends Report document the 
precipitous and unreversed decline of the most abundant species 
beginning in 1970. (Herbold et al. 1992). This downward trend is also 
apparent in the population data for winter run Chinook salmon. (Herbold 
et al. 1992).
    In choosing a particular year, EPA is not suggesting that the 
particular hydrological conditions in 1968 are being replicated. 
Instead, the use of an individual calendar year appears to be a 
reasonable surrogate for the level of development for that period. As 
the graph in Figure 2 suggests, there would not be a substantial 
difference between number of days of meeting the 2 ppt salinity value 
in 1968 versus 1967 or 1969. EPA has chosen the 1968 value as a 
reasonable representation of the period in which the estuary was 
attaining its designated uses.
    If the Estuarine Habitat criteria were stated on an annual basis as 
it was in [[Page 4678]] the Proposed Rule, the logistic equation 
corresponding to the 1968 line in Figure 1 would serve as the 
criteria's sliding scale correlating the number of days of meeting the 
2 ppt salinity value with annual unimpaired flow. As described below, 
however, this annual sliding scale must still be transformed into 
monthly sliding scales.
    (iii) Moving to Monthly Compliance.
    EPA has also refined the final rule to restate the Estuarine 
Habitat criteria on a month-by-month basis, rather than as a single 
number of days of compliance covering the entire February to June 
period.
    EPA received comments suggesting that the number of days of meeting 
the 2 ppt salinity value at Chipps and Roe Islands should be stated 
solely, or largely, in reference to the patterns of precipitation that 
could directly affect estuarine habitat during the period intended for 
protection. For example, criteria that are designed to protect 
conditions in the February-June period should reference only the 
unimpaired flows of February-June (or, possibly, January-June). 
Including precipitation in months outside of this February-June period 
could lead to inaccuracies in the criteria for February-June that could 
unnecessarily affect water project operations or inadequately protect 
the designated uses. This same problem could exist within the February-
June period. For example, if in a given year the precipitation in 
February is substantial, but the following months are very dry, the 
overall period of February-June would be considered very dry and, using 
the sliding scale for the entire February-June period, the number of 
days of compliance with the 2 ppt salinity value at Chipps or Roe 
Island would be very low. This result may contradict the actual natural 
hydrological cycle, which under this scenario would have provided at 
least one high water period for the estuarine habitat uses.
    A related issue raised by the comments and in the CUWA scientific 
workshops was the problem of how to develop compliance strategies for a 
given year based on a forecast of hydrological conditions expected 
during the following months. EPA agrees that this forecasting is 
unreliable, especially for the critical February and March months which 
are typically the months of most variable precipitation. Sliding scales 
such as Figure 1 (for Roe Island), which apply to the entire February 
to June period of protection, still require the project operators to 
forecast future hydrological conditions to meet the expected number of 
days of attainment with the 2 ppt criteria. For example, if February 
and March are wet, project operators have to forecast weather patterns 
for April to June to determine whether they should operate their 
projects to meet a substantial number of days of attaining the 2 ppt 
salinity value at Chipps or Roe Island (forecasting that the whole 
period will continue to be wet) or a lesser number of days (forecasting 
that the remaining months will be dry). Thus, the annual or five month 
approach described above and shown for Roe Island in Figure 1 would not 
address the issue of unreliable forecasts.
    To address this uncertainty in forecasting long range hydrology, 
and to provide criteria that more closely reflect the natural hydrology 
actually affecting the estuarine habitat, EPA is in the final rule 
restating the Estuarine Habitat criteria on a month-by-month basis. 
That is, the final criteria define the required number of days of 
compliance for a particular month solely by reference to the 
hydrological conditions of the previous month. This approach more 
precisely ties the salinity conditions affecting Estuarine Habitat with 
natural hydrological cycles reflecting the time when the estuary 
attained its designated uses, and is therefore consistent with EPA's 
overall approach to protecting the Estuarine Habitat designated use.
    Developing monthly sliding scales. EPA's analysis indicated that 
the required number of days of compliance with the 2 ppt criteria in a 
given month could be quite accurately predicted from logistic models 
using unimpaired flows of any of (a) the current month, (b) the 
previous month, (c) the previous two months, or (d) the previous and 
current month. Including the actual unimpaired flows of the current 
month, however, did not improve model performance and, in practice, the 
actual unimpaired flow of the current month cannot be known accurately 
until the month is over. EPA has, therefore, restated the criteria 
using the logistic equations described above, but only for one month at 
a time based on the preceding month's unimpaired flow.
    For example, the measured unimpaired flow in January would be used 
to set the number of days of compliance with the 2 ppt criteria at the 
Chipps and Roe Island locations. Similarly, measured unimpaired flow in 
February is used to set March's requirement. This approach has been 
labeled the ``Previous Month's 8-River Index'' (PMI) approach. To make 
this approach work, the sliding scales exemplified (for Roe Island) in 
Figure 1 have been transformed into monthly sliding scales. These 
monthly logistic equations for both Chipps and Roe islands are shown 
graphically in Figure 3.

                                                 BILLING CODE 6560-50-P
[[Page 4679]]

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BILLING CODE 6560-50-C
    Two technical revisions are being made to the criteria values 
generated by these monthly sliding scale equations. First, to 
facilitate compliance, the number of days resulting from the monthly 
equations will be rounded up or down to the nearest whole number. 
Second, at extremely low flows, the monthly equations include 
unjustified extrapolations beyond the existing data. For that reason, 
when the previous month's index is less than 500,000 acre-feet, the 
number of days of compliance required for the current month shall be 
zero.
    Revising the Roe Island ``trigger'' for monthly compliance. As a 
result of the above changes to the Estuarine Habitat criteria, the 
``trigger'' for the Roe Island location must be restated as a month-to-
month trigger. The Proposed Rule stated, in effect, that if the 
salinity dropped below 2 ppt at Roe Island at any time during the 
February to June period due to uncontrolled hydrologic conditions, the 
Roe Island requirements were ``triggered'' for the remainder of the 
February to June compliance period. In the final rule, the ``trigger'' 
is evaluated on a monthly basis. If the 14-day moving average salinity 
at Roe Island falls below 2 ppt on any day during the last 14 days of a 
month, compliance with the Roe Island criteria would be ``triggered'' 
for the following month.
    For example, assume that the sliding scale of unimpaired flow (PMI) 
for January indicates that the 2 ppt salinity value shall be attained 
for 18 days at Roe Island in February, if the Roe Island criteria is 
``triggered.'' If the 14-day moving average salinity in the last part 
of January is below 2 ppt at Roe Island, the Roe Island criteria would 
in fact be triggered for 18 days in February. Assume then that the 
system is operated to meet the 18 days in February, but that a large 
storm in mid-February results in the salinities of less than 2 ppt at 
Roe Island for the entire month of February. This would ``trigger'' the 
Roe Island criteria in March. If the sliding scale, PMI-based 
calculation required 31 days of compliance at Roe Island in March in 
this scenario, compliance for April (for 13 days, for example) would 
also be triggered, since the 2 ppt would be met during the last 14 days 
of March. If April is a dry month, the 2 ppt criteria could be met for 
the required 13 days early in the month, the 14-day moving average 
salinity in the last half of April would never go below 2 ppt at Roe 
Island, and the Roe Island criteria would not be triggered for May at 
all.
    Although somewhat complicated, this monthly triggering mechanism is 
essential to assure that the criteria applicable in a given month 
reflect the actual distribution of storm events throughout the February 
to June compliance period. As explained in more detail above, 
accounting for the natural hydrologic cycles in a manner reflecting the 
reference period assures protection of the designated uses without 
unnecessarily affecting water project operations.
    (iv) Alternative Measures of Attaining the Criteria.
    In the Proposed Rule, EPA indicated that it believed a State Board 
implementation plan that relied on the salinity-flow models, without 
making additional allowances for ``confidence intervals'', would 
adequately protect the designated uses. EPA's further review of the 
comments and continued discussions with the project operators has 
confirmed this belief.
    In addition, EPA believes that the Estuarine Habitat use would be 
protected if the Estuarine Habitat criteria are directly measured as 
either a daily salinity value or as a 14-day moving average salinity 
value. Further, EPA's review of the new CCWD model correlating flow and 
salinity suggests that the Estuarine Habitat use would be protected at 
the Chipps and Roe Island monitoring sites if the modeled ``flow 
equivalent'' of the applicable 2 ppt criteria is provided. According to 
the CCWD model, the steady state flows that would satisfy these flow 
equivalent requirements are 29,220 cubic feet per second (cfs) for the 
Roe Island monitoring site and 11,400 cfs for the Chipps Island 
monitoring site (Denton, pers. comm.). This ``flow equivalence'' 
measure of attainment with the criteria would not be available at the 
Confluence monitoring site because of assumptions in the CCWD model 
about antecedent conditions in Suisun Bay.23 [[Page 4680]] 

    \23\That is, to make this finding that the ``flow equivalence'' 
would protect the designated use at the Chipps and Roe Island 
locations, EPA had to make assumptions in the CCWD model that the 2 
ppt salinity value was actually being attained at the Confluence. 
Given that assumption, EPA cannot find that the ``flow equivalence'' 
at the Confluence is protective.
---------------------------------------------------------------------------

    Accordingly, the State Board could adopt an implementation plan 
providing that project operators would attain the criteria in any one 
of three ways: (1) the daily salinity value meets the requirement, (2) 
the 14-day moving average salinity meets the requirement, or (3) at the 
Chipps and Roe Island monitoring sites, the system is operated on that 
day so as to meet the ``flow equivalent,'' using the CCWD model, of the 
stated salinity criteria. EPA notes that the available modeling data 
indicate that under most circumstances, the most efficient approach (in 
terms of water usage) to meeting the criteria would be to attain the 
specified salinity value rather than the alternative flow equivalent.
c. Revised Estuarine Habitat Criteria
    Final estuarine habitat criteria reflecting the changes discussed 
above are shown below at 40 CFR 131.37(a)(1). These revised criteria 
provide the many equations necessary to define month-by-month sliding 
scales and, thereby, the applicable criteria.
    For illustration purposes only, Table 2 presents representative 
examples of the required number of days of compliance in different 
months across a range of possible values of the PMI index of unimpaired 
flow.

----------------------------------------------------------------------------------------------------------------
                                  Chipps Island                                Roe Island (if triggered)        
    PMI    -----------------------------------------------------------------------------------------------------
                Feb         Mar         Apr        May        Jun        Feb        Mar        Apr        May   
----------------------------------------------------------------------------------------------------------------
1000......  ..........         31           2          0          0         13          4          2          0 
1250......  ..........  ..........          7          0          0         17          7          4          0 
1500......  ..........  ..........         15          0          0         19         10          8          0 
1750......  ..........  ..........         21          0          0         21         13         11          0 
2000......  ..........  ..........         26          1          0         22         16         15          0 
2500......  ..........  ..........         29         16          1         24         20         21          2 
3000......  ..........  ..........         29         29          7         25         24         25          5 
4000......  ..........  ..........         30         31         25         26         27         28         18 
5000......  ..........  ..........  ..........  .........        29         27         29         29         26 
[[Page 4681]]                                                                                                   
                                                                                                                
6000......  ..........  ..........  ..........  .........        30         28         30         30         29 
----------------------------------------------------------------------------------------------------------------
Table 2. Examples of required number of days of compliance for each month across a range of possible values of  
  the 8-River Index for the prior month (PMI).                                                                  

2. Fish Migration Criteria

a. Overview
    (1) Importance of the Fish Migration and Cold Freshwater Habitat 
Criteria. The State's designated uses for the Bay/Delta include Cold 
Fresh-Water Habitat ``to sustain aquatic resources associated with a 
coldwater environment,'' and Fish Migration to ``[p]rovide[ ] a 
migration route and temporary aquatic environment for anadromous or 
other fish species.'' (1991 Bay/Delta Plan at 4-1). The migratory fish 
species associated with the cold fresh-water environment in the Bay/
Delta are chinook salmon (Oncorhynchus tshawytscha) and steelhead trout 
(Oncorhynchus mykiss).\24\

    \24\The State Board has designated both of these uses for the 
Bay/Delta estuary. However, in practice there is substantial overlap 
between them because many of the factors affecting the Cold Fresh-
Water Habitat use also affect those anadromous fishes migrating 
through the Delta to the ocean. Because of this overlap, this rule 
will, in protecting Fish Migration, benefit the Cold Fresh-Water 
Habitat use as well.

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BILLING CODE 6560-50-C [[Page 4683]] 
    Currently there are four distinct populations of salmon in the 
Sacramento/San Joaquin river systems, each named for the season of 
their migration upstream as adults. The fall-run population is now the 
most numerous. The San Joaquin River system supports only a fall-run 
population; the San Joaquin River spring-run became extirpated in the 
1940's. The Sacramento River system still supports small winter-run, 
spring-run and late fall-run populations, but these populations have 
all declined dramatically in recent years (USFWS 1992a, WRINT-USFWS-7; 
California DFG 1992a, WRINT-DFG-14). The winter-run population is now 
listed as threatened under the ESA. The spring-run population has 
recently reached low enough levels to be recognized as a species of 
special concern by the State of California, and NMFS has recently 
included the spring-run in its status review of salmon on the northwest 
coast of the United States (59 FR 46808 (09/12/94)).
    Steelhead trout are also cold fresh-water migratory fish within the 
Sacramento River System. They have suffered a 90 percent decline since 
the late 1960's, and are supported largely by hatchery production (CDFG 
1992a, WRINT-DFG-14).
    Salmon and steelhead migrating through the Delta to the ocean are 
subject to increased mortality when exposed to high temperatures and 
low flows and when diverted out of the main channels of the Sacramento 
and San Joaquin Rivers into less suitable habitat. Those fish diverted 
from the main river channels into the central and south Delta are also 
subject to increased mortality because of several factors including 
higher temperatures, increased predation and increased entrainment at 
the State and Federal pumping plants in the south Delta (USFWS 1992a).
    State and federal legislators have recognized the serious threat to 
the continued existence of migratory fishes in the Bay/Delta. In 1988, 
the California State legislature mandated a restoration goal of 
doubling natural salmon and steelhead production by the year 2000, and 
required development of a plan to meet this goal. Salmon, Steelhead 
Trout, and Anadromous Fisheries Program Act; codified at Cal. Fish & 
Game Code Sec. 6900 et seq. (West 1991). Also, the United States 
Congress recently enacted the Central Valley Project Improvement Act 
(CVPIA), which requires that a program be developed and implemented to 
make ``all reasonable efforts to ensure that * * * natural production 
of anadromous fish in Central Valley rivers and streams will be 
sustainable, on a long-term basis, at levels not less than twice the 
average levels attained during the period 1967-1991. * * *'' Central 
Valley Project Improvement Act Sec. 3406(b)(1), P.L. 102-575.
    (2) Proposed Rule. Many different factors affect the ability of 
salmon and steelhead to successfully migrate through the Delta to the 
ocean. These include water temperature, flow rates, diversions, 
operation of pumping facilities, and gate closures regulating the 
direction of water flows through the myriad channels and sloughs in the 
Delta. Clearly, any number of beneficial combinations of these factors 
could result in conditions that provide for successful migration and 
protection of the designated use. Accordingly, in formulating its 
Proposed Rule, EPA concluded that it would state its criteria 
generally, measuring the success of salmon in migrating through the 
Delta. That is, EPA would state goals that (1) called for a certain 
percentage of salmon to be able to survive their passage through the 
Delta, and (2) that could be achieved by any of a number of different 
management measures. In this way, the State Board would have maximum 
latitude to find combinations of management measures that would attain 
the salmon survival goal.
    In order to quantify the success of migrating salmon in passing 
through the Delta, EPA relied on ``salmon smolt survival models'' 
developed by the USFWS, one for the Sacramento River and one for the 
San Joaquin River.\25\ These salmon smolt survival models are 
mathematical equations stating the relationship between specific 
variables in the Delta (water flow rates, diversions into the central 
Delta, etc.) and salmon smolt survival.\26\ To predict the effect of a 
particular set of management measures (for example, a specified minimum 
flow and a specified maximum export flow), EPA inserts the management 
measures into the model equation. The model equation then generates an 
``index value'' representing the relative success of salmon migrating 
through the Delta while that set of management measures is being 
implemented.\27\

    \25\A ``smolt'' is a salmon in the process of acclimating to the 
change from a fresh water to a salt water environment. This occurs 
when young salmon migrate downstream through the Delta to the ocean.
    \26\These salmon smolt survival index equations were based in 
large part on the results of tagged-fish release and recapture 
experiments designed to measure and compare salmon smolt survival 
under a number of different physical conditions of varying migration 
pathways, water temperatures, flow rates, and rates of water exports 
from the Delta.
    \27\There was some disagreement among the commenters on the 
Proposed Rule as to whether these USFWS models yield index values 
that are literally ``percentages'' of the salmon smolts surviving 
through the Delta. All parties appear to agree, however, that these 
index values do in fact represent the relative survival compared to 
other index values. This preamble and accompanying rule will 
generally refer to these values as index values rather than as 
percentages.
---------------------------------------------------------------------------

    As its criteria, EPA proposed a set of index values representing 
successful salmon migration sufficient to protect the designated use. 
EPA established these target criteria index values by taking a set of 
USFWS recommendations of management measures that would protect the 
salmon resource, and translated (using the USFWS model equations) those 
protective management measures into index values. In other words, the 
criteria index values represented the level of salmon migration 
survival through the Delta that would occur if this particular set of 
protective management measures were adopted. The intent was not to 
mandate those particular management measures. Rather, it was to set a 
performance standard--measured by the criteria index value--for salmon 
survival. To attain the goal, the State Board would use either the 
specific management measures recommended by USFWS, or any other 
combination of measures that would yield the same level of survival of 
migrating salmon.
    The Proposed Rule named its criteria index values ``salmon smolt 
survival index criteria.'' For each of the Sacramento and San Joaquin 
River systems, the criteria provided a salmon smolt survival index 
equation (i.e. a USFWS model equation) and a set of index values to be 
attained. The index equation for each river quantified and predicted 
the survival of salmon smolt migrating through the Delta.
    The USFWS equations and EPA's Proposed Rule both ``scaled'' the 
index values to a scale of 0 to 1. This was done by dividing 
experimental release results by a constant of 1.8 (the highest release 
result). In the final rule, EPA is not ``scaling'' its criteria values. 
It is important to realize that criteria index values in the final rule 
are not actual survival estimates (such as a percentage of smolt 
surviving), but indices showing survival relative to other index 
values.\28\

    \28\For example, historically, the San Joaquin River index value 
has reached a number as high as 1.5 (which was attained in an 
experimental release at Jersey Point). For comparison, the average 
San Joaquin survival index value during low flow years is 0.09. This 
0.09 index value represents approximately 5 smolt recoveries from a 
release of 50,000 fish at Mossdale, 55 miles upstream of the 
recovery site at Chipps Island.
---------------------------------------------------------------------------

    In the Proposed Rule, the index values contained in the criteria 
varied according to the standard five water year types--each water year 
type had a [[Page 4684]] particular index value to be attained.\29\ The 
index values were to be attained by implementing management measures 
affecting the variables included in the index equations. For the 
Sacramento River, the index equation described a relationship between 
smolt survival and three variables: water temperature, water diversion 
out of the mainstem Sacramento River, and water export rates. For the 
San Joaquin, the variables were river flow rates, water diversion into 
the Upper Old River, and export rates.

    \29\As stated above, the standard water year categories are wet, 
above normal, below normal, dry, and critically dry years.
---------------------------------------------------------------------------

    The Proposed Rule included index values generally representing the 
modeled results of the management measures developed by the USFWS based 
on the work of the Delta Team of the Five Agency Chinook Salmon 
Committee.\30\ These management measures consist of export limits, 
minimum flows, channel gate closures, etc., during critical periods in 
the year. The estimated effects of these management measures on smolt 
survival were calculated using the criteria index equations.\31\ EPA 
concluded that these management measures, and the associated criteria 
index values, would lead to the protection of the designated Fish 
Migration use.

    \30\This interagency group consists of representatives from the 
USFWS, California DFG, California DWR, NMFS, and USBR. Its reports 
(Five Agency Delta Salmon Team, 1991a; 1991b) represent a consensus 
on the most effective and feasible implementation measures to 
protect downstream migrant salmon smolts in the Delta.
    \31\That is, management measures were evaluated as to their 
effect on the variables included in the index equations, and the 
index equations were then computed to derive criteria index values. 
The result was criteria index values that reflect the effects on 
survival of the recommended management measures.
---------------------------------------------------------------------------

    The resulting criteria index values were also consistent with the 
recommendations of the Interagency Statement of Principles signed by 
EPA, NMFS, and USFWS, which called for a level of protection for 
aquatic resources equivalent to the level existing in the late 1960's 
to early 1970's. To make this comparison, EPA compared its proposed 
criteria index values with the index values attained historically on 
the two river systems. See generally the discussion in the preamble to 
the Proposed Rule at 59 FR 824. The proposed Sacramento River criteria 
index values represented overall protection for the Fish Migration use 
at approximately the 1956-1970 historical level, whereas the proposed 
San Joaquin River criteria index values represented slightly better 
protection than the 1956-1970 historical level.
    The Proposed Rule also relied on the criteria index equations to 
determine whether the criteria were being attained. In effect, 
attainment would be assumed if the State adopted an implementation plan 
with a set of measures (export restrictions, flow requirements, etc.) 
that, when computed in the index equations, resulted in the criteria 
index value.
    (3) Final Criteria. EPA received substantial comment on its 
Proposed Fish Migration criteria. In addition, CUWA sponsored a number 
of scientific workshops to discuss the Proposed Rule, and EPA 
participated in these discussions. In response to the comments and 
scientific workshops, EPA developed a revised approach to the Fish 
Migration criteria, which was summarized in the documents made 
available to the public in EPA's Notice of Availability published in 
the Federal Register on August 26, 1994 (59 FR 44095).
    The final rule maintains the fundamental approach of the Proposed 
Rule, but it has been revised in a number of ways to address several 
concerns. The major changes are:
    (i) The methodology for establishing the criteria index values has 
been revised. Consistent with the discussion in the materials made 
available in the Notice of Availability, the criteria values on the 
Sacramento and San Joaquin River systems are described separately and 
the index values have been derived in different ways.
    (a) On the Sacramento River, the criteria index values vary 
according to the water temperature at Miller Park. ``Ceiling'' and 
``floor'' criteria index values are included to reflect the fact that 
at very high water temperatures, the Fish Migration use needs 
additional protection, and at very low water temperatures, temperature 
is unlikely to affect fish migration. The actual index values have been 
set to replicate the survival values that would be attained if the 
Delta Cross-Channel\32\ were closed during the critical migration 
period. The Sacramento River tagged-fish release results indicate that, 
except in very high temperature periods, those periods in which the 
Delta Cross-Channel is closed provide aquatic conditions allowing for 
the protection of the Fish Migration designated use.

    \32\The Delta Cross Channel is a controlled diversion channel 
between the Sacramento River and Snodgrass Slough. Water is diverted 
from the River through the Slough and then through natural channels 
for almost 50 miles southward to the State and Federal pumping 
plants.
---------------------------------------------------------------------------

    (b) On the San Joaquin River, the criteria index values vary 
according to unimpaired San Joaquin river flow. The actual index values 
have been set to approximately replicate the survival values that would 
be attained if a series of management measures (flow requirements, 
export restrictions, barriers, etc.) recommended by the USFWS based on 
the work of the Delta Team of the Five Agency Chinook Salmon Committee 
were implemented. The tagged-fish release results indicate that these 
or equivalent management measures are necessary to protect the Fish 
Migration designated use on the San Joaquin.
    (ii) The criteria have been restated as sliding scales or 
continuous functions. As described in EPA's alternative formulation of 
the Fish Migration criteria referenced in the Notice of Availability, 
59 FR 44095, and as in the case of the Estuarine Habitat criteria 
discussed above, stating the criteria index values with reference to 
the five water year types may create problems\33\ in protecting the 
Fish Migration use. Accordingly, the final criteria index values are 
expressed as a continuous function.

    \33\For example, if a mid-year change in water year types 
occurs, the Proposed Rule may have called for drastic changes in the 
flow regime, potentially leading to dewatering or washing away 
newly-spawned eggs.
---------------------------------------------------------------------------

    (iii) Direct experimental measurements of salmon survival through 
the Delta will be used to estimate attainment of the criteria, instead 
of relying on estimates of attainment generated by the criteria index 
equations. This change allows the State Board more flexibility to 
develop implementation measures because it does not tie attainment of 
the criteria to the particular variables (exports, flows, etc.) 
included in the criteria index equations. This also transforms the 
final criteria into an explicit ``performance standard'', in which the 
criteria index values serve as the statement of desired protection for 
the Fish Migration use.
b. Detailed Discussion

(1) Proposed Rule

    To protect the Fish Migration designated use, the Proposed Rule 
included ``salmon smolt survival index criteria.'' For each of the 
Sacramento and San Joaquin River systems, the criteria provided a 
salmon smolt survival index equation and a set of index values to be 
attained. The index equation for each river quantified and predicted 
the survival of salmon migrating through the Delta.
    These index equations were developed by the USFWS (Kjelson, et al. 
1989; USFWS 1992a, 1992b), and were based on the results of tagged-fish 
[[Page 4685]] release and recapture experiments measuring and comparing 
salmon smolt survival under a number of different physical conditions 
of varying migration pathways, water temperatures, flow rates, and 
rates of water exports from the Delta. On the Sacramento River, over 
the past 14 years, USFWS has performed a series of studies, releasing 
coded-wire tagged smolts at Sacramento and using recapture data to 
estimate an index of their survival to Chipps Island. Similarly, on the 
San Joaquin River, between 1982 and the present, the USFWS has 
conducted a series of experimental releases and captures of tagged 
salmon smolts in the San Joaquin River system, and has used the data 
collected in these experiments to develop a smolt survival index model 
for that basin (Brandes 1994).\34\ EPA believes that the smolt survival 
indices from these releases do in fact represent the pattern of smolt 
survival through the Delta, and this belief was generally confirmed by 
the scientific workshops sponsored by CUWA (Kimmerer 1994b). As noted 
above, USFWS and the EPA Proposed Rule both ``scaled'' the index values 
by dividing experimental release results by 1.8.

    \34\Since the Proposed Rule was published, and as described in 
the alternative formulation of the Fish Migration criteria made 
available in EPA's Notice of Availability (59 FR 44095), USFWS has 
developed a revised version of the San Joaquin River model. This 
model relates the survival of San Joaquin basin smolts migrating 
through the Delta to: (1) San Joaquin River flow at Vernalis, (2) 
proportion of flow diverted from the mainstem San Joaquin River, (3) 
exports, and (4) temperature at Jersey Point. The revised San 
Joaquin model structure overall is very similar to that of the 
Sacramento basin model. This revised model should be more useful 
than the previous version for analyzing alternative implementation 
measures.
---------------------------------------------------------------------------

    In the Proposed Rule, the index values contained in the criteria 
varied according to the standard five water year types. The proposed 
criteria index values were stated in tabular form as in Table 3, below. 
The index values were to be attained by implementing management 
measures affecting the variables included in the index equations. For 
the Sacramento River, the index equation stated a relationship between 
smolt survival and three variables: water temperature, water diversion 
out of the mainstem Sacramento River, and water export rates. For the 
San Joaquin, the variables were river flows rates, water diversion into 
the Upper Old River, and export rates.
    The Preamble to the Proposed Rule discussed in detail how the 
actual criteria index values in Table 3 were determined. To protect the 
designated uses, the Proposed Rule included index values representing 
the modeled results of the management measures proposed by USFWS based 
on the work of the Delta Team of the Five Agency Chinook Salmon 
Committee, with the exception of certain recommendations regarding the 
Georgiana Slough. The management measures consisted of export limits, 
minimum flows, channel gate closures, etc., during critical periods in 
the year. As explained in the preamble to the Proposed Rule (59 FR 
825), EPA was concerned that the Delta Team recommendation to close the 
Georgiana Slough would have deleterious effects on the Delta smelt and 
other aquatic life in the central Delta, and possibly on adult salmon 
returning upstream. Thus, the management measures underlying the 
recommended criteria index values did not assume that the Slough would 
be closed. EPA concluded that these management measures, if implemented 
by the State, would lead to the protection of the designated Fish 
Migration use.
    EPA then evaluated the effects of these management measures on the 
variables contained in the models, and calculated the criteria index 
values using the model's equations. The result was criteria index 
values that reflect effects on survival as a result of implementing the 
recommended management measures.
    Although the criteria index values were set by reference to the 
protective management measures, the resulting criteria index values 
were also consistent with the recommendations of the Interagency 
Statement of Principles signed by EPA, NMFS, and USFWS, which called 
for a level of protection for aquatic resources equivalent to the level 
existing in the late 1960's to early 1970's. To make this comparison, 
EPA compared its proposed criteria index values with the index values 
attained historically on the two river systems. The historical index 
values were developed by the USFWS. See USFWS, 1992c (WRINT-USFWS-8); 
also 59 FR 824. The proposed Sacramento River criteria index values 
represented overall protection for the Fish Migration use at 
approximately the 1956-1970 historical level, whereas the proposed San 
Joaquin River criteria index values represented slightly better 
protection than the 1956-1970 historical level. Both sets of criteria 
index values represented better protection than the 1956-1970 
historical period in drier years, and less protection in wetter years. 
These proposed criteria index values were intended to reflect more 
consistent smolt survival and help avoid situations where extraordinary 
measures would be necessary to preserve runs, particularly in the San 
Joaquin River tributaries.

                Table 3.--Proposed Salmon Smolt Criteria                
------------------------------------------------------------------------
          Sacramento River                    San Joaquin River         
------------------------------------------------------------------------
                           Criteria                             Criteria
     Water year type         value        Water year type         value 
------------------------------------------------------------------------
Wet......................      .45   Wet......................      .46 
Above Normal.............      .38   Above Normal.............      .30 
Below Normal.............      .36   Below Normal.............      .26 
Dry......................      .32   Dry......................      .23 
Critical.................      .29   Critical.................      .20 
------------------------------------------------------------------------

    Finally, the Proposed Rule also relied on the criteria index 
equations to determine whether the criteria were being attained. In 
effect, attainment would be assumed if the State adopted an 
implementation plan with a set of measures (export restrictions, flow 
requirements, etc.) that, when computed in the index equations, 
resulted in the criteria index value. This approach assumed that the 
criteria index equations included all of the important variables 
determining smolt survival and correctly stated the interrelationship 
of those variables, so that actual measurement of attainment would be 
unnecessary.
    The final Fish Migration criteria reflect the following changes 
from the Proposed Rule: (i) the methodology for establishing the 
criteria index values has been revised, (ii) the criteria have been 
restated as sliding scales or continuous functions, and (iii) direct 
experimental measurements of salmon survival will be used to measure 
attainment of the criteria.

(i) Revised Method of Selecting Criteria Index Values

    As discussed in the materials referenced in EPA's Notice of 
Availability (59 FR 44095), EPA has revised its approach to stating and 
developing the criteria index values used in the final criteria. The 
primary change in the final rule is that EPA has revised the underlying 
management measures used to generate the criteria index values. On the 
Sacramento River, available information indicates that closing the 
Delta Cross Channel during the spring migration period is the most 
important factor in the protection of the Fish Migration designated 
use, primarily because closing the Channel prevents migrating fish from 
being pulled into the inner Delta where survival is significantly 
lower. Accordingly, the criteria index values were based on tagged-fish 
release results for migration periods when the Delta Cross Channel was 
closed. Similarly, [[Page 4686]] EPA believes that on the San Joaquin 
River the management measures recommended by USFWS (with the minor 
adjustments described below) will protect the designated uses. 
Accordingly, the criteria index values for the San Joaquin were derived 
from the modeled values associated with these management measures.

(a) Sacramento River Fish Migration Criteria

    On the Sacramento River, the criteria index values vary according 
to the water temperature at Miller Park at the time of the tagged fish 
release. ``Ceiling'' and ``floor'' criteria index values are included 
to reflect the fact that at very high water temperatures, the Fish 
Migration use needs additional protection, and at very low water 
temperatures, temperature is unlikely to affect fish migration. The 
actual index values have been set to replicate the survival values that 
would be attained if the Delta Cross-Channel were closed during the 
critical spring migration period. The Sacramento River tagged-fish 
release results indicate that, except in very high temperature periods, 
those periods in which the Delta Cross-Channel is closed provide 
aquatic conditions allowing for the protection of the Fish Migration 
designated use.
    (I) Using Temperature as the Independent Variable for the Criteria. 
In the Proposed Rule, Sacramento River criteria varied according to 
water year types reflecting precipitation in the Sacramento River 
Basin. Using water year type as the ``independent variable'' in the 
criteria allowed EPA to match criteria index values with the natural 
variation in precipitation. Further analysis of the USFWS tagged-fish 
release studies suggests that temperature is a dominant factor 
influencing salmon smolt survival in the Sacramento River. Temperature 
at release alone is significantly related to salmon smolt survival 
(Letter from P. Fox to L. Hoag, California Urban Water Agencies, dated 
July 13th, 1994).
    Because water temperature in the Delta is largely independent of 
management measures in the Delta (in that it varies naturally with 
ambient weather conditions), EPA will adopt final Fish Migration 
criteria that vary based on water temperature. That is, the criteria 
index values will call for higher smolt survival at lower water 
temperatures, and lower smolt survival at higher water temperatures. 
This variation in the criteria index values with temperature follows 
the pattern of the natural variability of temperature and survival 
existing on the Sacramento River during periods in which the Fish 
Migration designated use is attained.
    Although it is generally adopting water temperature as the 
independent variable for the Sacramento River Fish Migration criteria, 
EPA is modifying the approach in two ways in order to better protect 
the designated use. First, at very high water temperatures (those above 
72 deg. F), measured smolt survival index values approach zero. These 
high temperature conditions are clearly not consistent with protection 
of the Fish Migration use. Protective measures should therefore be used 
to increase survival of smolts throughout this period, even at times of 
high temperature. To this end, USFWS has recommended additional 
management measures (primarily export restrictions) to restrict passage 
of fish into the warm waters of the central Delta and, thus, lower 
mortality of smolts as they pass through the Delta (USFWS 1992a). It is 
EPA's judgment that these measures should be used to reduce the serious 
degradation in migration conditions occurring during high temperature 
periods. EPA believes, therefore, that a ``floor'' to the Fish 
Migration criteria is appropriate so as to encourage efforts to protect 
salmon during these periods of high temperature. EPA has included such 
a ``floor'' at the 72 deg. F temperature level in its final Sacramento 
River Fish Migration criteria.
    Similarly, at lower temperatures, the smolt survival index values 
likely approach a maximum at some point. The highest survival index 
recorded (1.48) coincided with the lowest temperature at release 
recorded during salmon smolt survival experiments (61 deg.F). Below 
this temperature, it is unlikely that lower water temperatures would 
lead to a substantially increased survival. In other words, once water 
temperature reaches the lower temperatures beneficial to smolt 
survival, additional decreases in the temperature would not be expected 
to significantly increase survival. This suggests that the Fish 
Migration criteria should include a ``ceiling'' value associated with 
those low temperatures. Otherwise, the criteria would state that 
continued lowering of water temperature should yield higher and higher 
survival. This result is unlikely to be valid. EPA is therefore placing 
a ``ceiling'' on the criteria index values corresponding to the 
61 deg.F level.
    (II) Establishing criteria values. To set the actual criteria 
values, the final rule relies on the recommendation by USFWS that the 
Delta Cross Channel be closed at critical times during the spring 
salmon migration period (USFWS 1992a). Recent investigations by USFWS 
indicate that closing the Delta Cross Channel is the most important 
factor in the protection of smolts on the Sacramento River (USFWS 
1992b). The historical experimental release results support this 
hypothesis, in that data points derived from periods when the Cross 
Channel was closed show a significant and consistent improvement in 
survival compared to periods when it is open (USFWS 1992b).35

    \35\This is particularly true for release studies at Sacramento. 
Release studies at Courtland (downstream of Sacramento) showed less 
dramatic improvement with the Cross Channel closed, suggesting that 
other factors such as those included in the USFWS model are also at 
work.
---------------------------------------------------------------------------

    Based on this beneficial relationship between survival and the 
closure of the Delta Cross Channel, EPA has concluded that criteria 
index values corresponding to a closed Delta Cross Channel (adjusted to 
provide a floor for high temperature periods) would reflect conditions 
protecting the Fish Migration designated use on the Sacramento River. 
Accordingly, the final rule adopts criteria index values, stated (as 
explained below) as a continuous function or line, to 
approximate36 the experimental survival index values observed for 
Sacramento releases during periods in which the Channel is closed. The 
continuous function or line for these criteria index values can be 
stated as a simple linear equation (Index value = 6.96 - .092 * 
Fahrenheit temperature).

    \36\Approximating this line was done through a standard least 
squares ``best fit'' computation.
---------------------------------------------------------------------------

    This approach to developing criteria index values addresses some of 
the concerns about the criteria index equations raised in the public 
comments and at the CUWA scientific workshops. Some commenters believed 
that the complexity and structure of the equations resulted in too much 
uncertainty about their statistical reliability. The revised approach 
used in the final rule reduces this problem because it sets the 
criteria index values using observed tagged-fish release results 
instead of modeled or computed values.
    The final criteria index value line described above very closely 
approximates the line created by doubling the historical survival data 
measured at times that the Delta Cross Channel is open. These different 
lines, and the underlying data, are summarized in Figure 4. Although 
not intentional, the near-coincidence of the final criteria index value 
line and the doubling line provides an independent policy rationale for 
adopting this target index, in that the Central Valley Project 
[[Page 4687]] Improvement Act mandates a ``doubling'' goal for 
anadromous fish.

BILLING CODE 6560-50-P
[GRAPHIC][TIFF OMITTED]TR24JA95.005



BILLING CODE 6560-50-C [[Page 4688]] 
    Historical information confirms the validity of the final 
Sacramento River Fish Migration criteria, in that the criteria index 
values developed in this final rule are consistent with the modeled 
index values representing conditions in the late 1960's to early 
1970's. As stated by EPA in the Proposed Rule, the level of protection 
on the Sacramento River during this historical period was consistent 
with the protection of the Fish Migration designated use.
    (III) Revised Sacramento Fish Migration Criteria. The revised 
criteria (Sacramento River Fish Migration Criteria or SRFMC) are stated 
in reference to water temperature. As explained above, use of this 
linear equation appears inappropriate at both very high and very low 
temperatures, so the criteria must specify a ceiling on the index 
values at low temperatures and a floor for high temperatures. 
Incorporation of these conclusions and comments leads to the following 
Fish Migration criteria:
At temperatures below 61 deg.F:
    SRFMC=1.35
At temperatures between 61 deg.F and 72 deg.F:
    SRFMC=6.96 - .092 * Fahrenheit temperature
At temperatures above 72 deg.F:
    SRFMC=0.34
    In all cases, water temperature is the temperature at release of 
tagged salmon smolts into the Sacramento River at Miller Park.
    These final criteria are shown in Figure 5. Note that the 
``ceiling'' and ``floor'' values in the final rule differ somewhat from 
those included in the documents made available in EPA's Notice of 
Availability (59 FR 44095). The changes were made to correct 
computational errors in evaluating the applicable ``continuous 
function'' values for the 61 deg.F and 72 deg.F ceiling and floor 
levels.

                                                 BILLING CODE 6560-50-P
[[Page 4689]]

[GRAPHIC][TIFF OMITTED]TR24JA95.006



BILLING CODE 6560-50-C
    (IV) Implementation. On the Sacramento River, the criteria provide 
survival goals that vary based on the water temperature at the time of 
release of the tagged salmon smolts. EPA believes that the 
implementation plan developed by the State Board should provide for a 
sufficient number of fish releases each year to determine whether the 
criteria are being attained over a representative range of temperature 
conditions. EPA recognizes that there may be substantial variation in 
fish migration criteria values resulting from these experimental 
releases. Accordingly, the final rule provides that attainment can be 
measured using a three-year moving average (the current year and two 
preceding years). Three year periods should provide time to complete 
sufficient releases to determine whether the implementation measures 
are, on average, attaining the stated criteria values.
    The State Board may consider using the USFWS Sacramento smolt 
survival model (that is, the model underlying the criteria index 
equations) to predict measures necessary to attain the criteria. There 
are a number of base conditions underlying both the tagged-fish release 
experiments and the USFWS models. For example, USFWS recommended a base 
Sacramento River flow to ensure that overall conditions do not 
deteriorate. The State should protect these base conditions as it 
develops an implementation plan.
    Monitoring attainment of these criteria should focus on both 
within-year measures and across-year comparisons. During each year 
monitoring of salmon smolt survival should occur throughout the months 
of April, May and June with particular emphasis during times of 
temperature change or at times of change in water project operation. It 
is likely that this monitoring will reveal a large variability in 
survival at different times and under different conditions within each 
year. EPA anticipates that at the time of the next triennial review 
enough monitoring data over a range of temperatures will be available 
for a preliminary determination of whether the State's implementation 
actions attain the criteria.

(b) San Joaquin River Fish Migration Criteria

    On the San Joaquin River, the criteria index values vary according 
to unimpaired San Joaquin river flow. The actual index values have been 
set to approximately replicate the survival values that would be 
attained if a series of management measures (flow requirements, export 
restrictions, barriers, etc.) recommended by the USFWS were 
implemented. The tagged-fish release results indicate that these or 
equivalent management measures are necessary to protect the Fish 
Migration designated use on the San Joaquin.
    (I) Using Unimpaired Flow at Vernalis as the Independent Variable 
for the Criteria. In the Proposed Rule, San Joaquin River criteria 
varied according to water year types reflecting precipitation in the 
San Joaquin River basin. Using the water year type as the ``independent 
variable'' allowed EPA to match the criteria index values with the 
natural variation in precipitation. Further analysis has confirmed that 
water flow at Vernalis shows a significant correlation with survival 
indices representing total survival through the Delta,37 
suggesting that criteria index values should vary with the natural 
hydrology. That is, the criteria index values should reflect higher 
survival during wetter years with more precipitation and lower survival 
during drier years. This variation replicates the natural hydrological 
cycles affecting Fish Migration through the estuary. [[Page 4690]] 

    \37\EPA considered water temperature at release, smolt size at 
release, and water flow at Vernalis as potential independent 
variables affecting survival. Based on the studies done to date, it 
appears that neither water temperature at release nor smolt size 
show a significant correlation with the smolt survival indices 
representing smolt survival through the San Joaquin Delta (P. Fox, 
Data summary presented at CUWA workshop on June 29, 1994). Note that 
results from upstream site releases (at Snelling and on the lower 
Stanislaus and Tuolumne Rivers) were included in this correlation 
between flow and survival index values in order to supplement data 
from wetter years. This approach assumed that the mortality between 
the upstream release sites and the downstream Mossdale, Dos Reis and 
Upper Old River release sites (all close together) is negligible. If 
incorrect, this assumption may bias the correlation downward, and 
survival through the Delta may have been better than the index 
indicates for those releases.
---------------------------------------------------------------------------

    The Proposed Rule varied criteria index values according to the 
five water year types, and in that way reflected natural hydrological 
cycles. In the final rule, however, EPA is using the 60-20-20 
unimpaired San Joaquin flow index38 as a readily-available 
estimate of natural hydrology. When used in a continuous function (as 
described below), the 60-20-20 index allows a much more precise 
statement of the natural hydrology than the five water year categories.

    \38\The San Joaquin water year index (denoted the San Joaquin 
Valley Index in the final rule language) is the commonly-accepted 
method for assessing the hydrological conditions in the San Joaquin 
basin. It is also frequently referred to as the 60-20-20 index, 
reflecting the relative weighting given to the three terms (current 
year April to July runoff, current year October to March runoff, and 
the previous year's index) that make up the index.
---------------------------------------------------------------------------

    (II) Establishing Criteria Index Values. To establish the actual 
values included in the San Joaquin River Fish Migration criteria, EPA 
first developed survival values associated with the implementation of 
management measures proposed by USFWS (USFWS 1992a). These USFWS 
measures include export limits at certain times, a barrier at Old River 
during April and May, and minimum flows at Vernalis, and are summarized 
in Table 5.39 As indicated in the Proposed Rule, EPA believes that 
implementation of these management measures would provide conditions 
protecting the designated Fish Migration use.

    \39\As explained above, the index values shown in Table 6 (both 
USFWS and EPA values) have been ``scaled'' by dividing by 1.8. This 
scaling allows a direct comparison with the Proposed Rule index 
values, which were also scaled. EPA's final criteria index values 
have not been scaled, to facilitate measurement of attainment 
through actual experiments as discussed below.
---------------------------------------------------------------------------

    Modifying management measures. As explained below, EPA has revised 
its assessment of some of the USFWS management measures (notably, those 
involving the Upper Old River barrier). Accordingly, the final rule 
used the following management measures: (1) A one month (April 15 to 
May 15), instead of USFWS's two month (April 1 to May 31), requirement 
for the Upper Old River barrier placement, (2) increased export 
restrictions (to 1500 cfs) during the time the Old River barrier is in 
place, (3) increased flow (to an average of 4000 cfs rather than 
USFWS's 2000 cfs) in critical years when the barrier is in place, and 
(4) flows and exports varying each year according to the 60-20-20 water 
year index, rather than using the USFWS proposal to vary measures by 
water year type. EPA's measures (stated as averages for each water year 
type) are also shown in Table 4.
    EPA revised the management measures recommended by USFWS because 
recent discussions with USFWS and others, as well as information 
developed in hydrological modeling for the South Delta Barriers Project 
(California DWR 1993), raised concerns that an Upper Old River barrier 
might increase reverse flows in the central Delta. Such an increase has 
the potential to draw fish into poor habitat and to increase 
entrainment of fish at the project pumps. This is of particular concern 
for the threatened Delta smelt. Because the barrier is expected to 
provide greatly increased protection for migrating salmon smolts, EPA 
continues to believe, as it expressed in the Proposed Rule, that an 
Upper Old River barrier is an important implementation measure. 
However, in order to prevent an increase in detrimental central Delta 
reverse flows, EPA is revising the USFWS management measures to include 
only one month with the barrier in place, rather than the two months 
initially recommended by USFWS.40

    \40\As in the Proposed Rule, EPA assumed that exports would be 
reduced to no more than 1500 cfs while the barrier is in place, to 
help alleviate hydrological problems caused by the barrier. Minimum 
flows during the time the barrier is in place are assumed to be an 
average of approximately 4000 cfs during dry and critically dry 
years to provide an increased ratio of flows to exports in the lower 
San Joaquin, thereby further reducing potential problems caused by 
reverse flows. Management measures assumed in developing the 
criteria values also included export restrictions during the times 
in April and May when the barrier is not in place. These maximum 
export rates are: in critically dry years, 2000 cfs; dry years, 3000 
cfs; below normal years, 4000 cfs; above normal years, 5000 cfs; and 
wet years, 6000 cfs.

                                                                        
[[Page 4691]]                                                           
                               Table 4.--San Joaquin Management Measures Compared                               
----------------------------------------------------------------------------------------------------------------
                     Max Total CVP/SWP      Barrier Upper Old                                   Index Values on 
   Alternative         Exports in cfs             River                 Vernalis Flow             San Joaquin   
----------------------------------------------------------------------------------------------------------------
EPA..............  4/15 to 5/15 1500      4/15 to 5/15 All Year  4/15 to 5/5 Minimum CFS      ..................
                   4/1 to 4/15 & 5/16 to   Types                 W  10000                     W  .49\2\         
                    5/31                                         AN  8000                     AN  .35           
                   W\1\  6000                                    BN  6000                     BN  .28           
                   AN  5000                                      D  4000                      D  .22            
                   BN  4000                                      C  4000                      C  .22            
                   D  3000                                       Other flows from 4/1 to 5/   Avg = .33         
                   C  2000                                        31 same as DWRSIM run used                    
                                                                  by USFWS for D-1630                           
USFWS............  4/15 to 5/15           4/1 to 5/31 All Year   4/15 to 5/15 Minimum CFS     ..................
                   W  6000                 Types                 W  10000                     W  .49            
                   AN  5000                                      AN  8000                     AN  .41           
                   BN  4000                                      BN  6000                     BN  .40           
                   D  3000                                       D  4000                      D  .35            
                   C  2000                                       C  2000                      C  .32            
                                                                 Other flows from 4/1 to 5/   Avg = .41         
                                                                  31 same as DWRSIM run used                    
                                                                  by USFWS for D-1630                           
----------------------------------------------------------------------------------------------------------------
\1\Many of the management measures in Table 4 vary by the water year category. Those categories are wet (W),    
  above normal (AN), below normal (BN), dry (D) and critically dry (C).                                         
\2\For comparison purposes, both EPA and USFWS index values have been scaled by dividing by 1.8. The final EPA  
  criteria have not been scaled.                                                                                

    Criteria index values. Having arrived at this set of management 
measures that would protect the Fish Migration designated use (and not 
adversely affect the Delta smelt), EPA used the USFWS survival index 
equations to develop criteria index values across the potential range 
of hydrological conditions.41 Note that, as distinguished from the 
Proposed Rule, EPA is including only the criteria index values as its 
final Fish Migration criteria. The Proposed Rule had also included the 
criteria index value equations in the criteria. By including only the 
goal or target index values in the final criteria, EPA is providing 
greater latitude to the State Board to develop a mix of management 
measures that attain the stated salmon survival.

    \41\The final Fish Migration criteria on the San Joaquin River 
do not vary by temperature (as they do for the Sacramento River) 
because experimental data from releases near the upstream edge of 
the Delta did not show a significant statistical relationship 
between survival and temperature at release (P. Fox, Data summary 
presented at CUWA workshop on June 29, 1994). In other words, on the 
San Joaquin River, temperature should not be used as the independent 
variable in the criteria. Nevertheless, temperature at Jersey Point 
is one of the factors included in the revised USFWS San Joaquin 
River model, and, as described above, that model was used in 
developing EPA's final criteria to gauge the probable effect of 
implementation measures on smolt survival. When computing modeled 
smolt survival, EPA assumed average water temperatures of 60  deg.F 
in April and 65  deg.F in May. These assumed values are averages 
from a set of temperature data at Jersey Point taken during the late 
1950's and 1960's. The recent experimental release temperatures are 
within the range of this data.
---------------------------------------------------------------------------

    Means of these modeled values for each water year type are shown in 
Table 4. To translate these discrete values into a continuous function 
(as discussed below), two lines of ``best-fit'' were created, one for 
the drier years (dry and critically dry) and one for the wetter years 
(wet, above normal, and below normal). By connecting these two lines, 
EPA created a continuous function to serve as the criteria index value 
line on the San Joaquin. This criteria index value line is shown in 
Figure 6.

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BILLING CODE 6560-50-C
    Dry year v. wet year protection. These final criteria index values 
represent a larger relative increase in survival over current survival 
rates in dry and critical years (compared to wetter years) so as to 
protect salmon populations from declining to the critically low levels 
of recent years. The results from tagged-fish releases on the San 
Joaquin River show significantly different survival at high versus low 
flow conditions (USFWS 1992b; Brandes 1994). Most of the release 
studies have been performed at flows below 5,000 cfs, and it is clear 
from the relation between survival indices and experimental flow 
conditions that these conditions are very poor for smolt survival and 
are inadequate to protect the Fish Migration designated uses. The 
average survival index for these low flow conditions is 0.09, whereas 
these index values have attained values as high as 1.5 on the San 
Joaquin (a Jersey Point release).42 Although there is less 
information at higher flows, the experimental results do indicate that 
survival has been substantially higher under these conditions. The 
average survival index at these higher flows is 0.48. [[Page 4693]] 

    \42\These numbers are not ``scaled'', and are thus indices 
showing survival relative to other index values. The 0.09 average 
index value represents approximately 5 recoveries from a release of 
50,000 fish at Mossdale, 55 miles upstream of the smolt recovery 
site at Chipps Island.
---------------------------------------------------------------------------

    To address this relative difference in survival during high and low 
flow periods, EPA is adopting criteria index values reflecting a 
relatively larger improvement in survival in low flow years than in 
high flow years. That is, conditions for migrating fish in drier 
periods have been relatively worse, so the criteria index values 
applicable to the drier periods must reflect conditions that are 
relatively more improved in order to protect the Fish Migration 
designated use.
    Although the final criteria call for relatively higher protection 
in drier years, it is also particularly important in the San Joaquin 
basin to protect salmon during periods of higher flow conditions. The 
years of higher flows have been the only times recently when the Fish 
Migration use has come close to being attained, and protection in these 
productive years is important for buffering the salmon population 
against permanent loss of salmon runs when conditions are poor. To 
address these special concerns across the spectrum of hydrological 
conditions, these final criteria index values, on average, increase wet 
year survival by a factor of 1.8 and critically dry year survival by a 
factor of 4.
    EPA has considered the concerns expressed by some CUWA workshop 
participants about using the USFWS models to establish criteria index 
values. The CUWA workshop participants developed a consensus, based not 
on the USFWS-modeled values but on their independent scientific 
judgment, that an increase in measured survival index values of two to 
three times recently observed values would be appropriate in critical 
years (Kimmerer 1994b). As stated above, the CUWA workshop participants 
also endorsed relatively higher protection in drier years as opposed to 
wetter years (Kimmerer 1994b). EPA agrees with these scientific 
judgments, and believes that measured criteria index values in these 
ranges must be attained to protect the designated uses on the San 
Joaquin.
    The criteria index values shown as a continuous function in Figure 
6, even though developed with the assistance of the USFWS model, are 
wholly consistent with the findings of the CUWA workshop participants 
(Kimmerer 1994b). In addition, these target values are, on average, 
consistent with the historical 1956-70 average survival index for the 
more protective wetter years of that period (wet, above normal, and 
below normal water years) as calculated using the USFWS model (Brandes 
1994). The target values are also consistent with the CVPIA goal of 
doubling anadromous fish populations. For comparison, the final 
criteria index value line is displayed in Figure 7 with the recent 
historical survival line (based on the tagged fish release results) and 
a line representing twice the recent historical survival line.

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[[Page 4694]]

[GRAPHIC][TIFF OMITTED]TR24JA95.008


6560-50-C [[Page 4695]] 
    (III) Revised San Joaquin Fish Migration Criteria. The criteria 
index value line is being stated in the final rule as follows:

For years in which the SJVIndex is > 2.5:
    SJFMI = (-0.012) + 0.184*SJVIndex
In other years:
    SJFMI = 0.205 + 0.0975*SJVIndex
where SJFMI is the San Joaquin Fish Migration index, and SJVIndex is 
the 60-20-20 San Joaquin water year index in million acre feet (MAF).
    These criteria are displayed graphically in Figure 6.
    (IV) Implementation of San Joaquin River Fish Migration Criteria.
    The following discussion is intended to assist the State Board's 
consideration of the issues involved in implementing these or similar, 
equally protective, criteria.
    The San Joaquin River Fish Migration criteria provide an annual 
survival goal that varies depending on the 60-20-20 San Joaquin water 
year index. EPA anticipates that the State Board implementation plan 
would provide for a sufficient number of tagged fish releases to verify 
that the applicable criterion is being met in each year. EPA recognizes 
that there may be substantial variation in fish migration criteria 
values resulting from these experimental releases. Accordingly, the 
final rule provides that attainment can be measured using a three-year 
moving average (the current year and two preceding years). Three year 
periods should provide time to complete sufficient releases to 
determine whether the implementation measures are, on average, 
attaining the stated criteria values.
    As stated above, the USFWS model is the best available model of 
salmon smolt survival through the Delta, and EPA encourages the State 
Board to use the recently revised USFWS San Joaquin model as guidance 
for setting implementation measures. Nevertheless, it is important to 
recognize that there may be constraints on the model's use. Further 
monitoring and experimental releases under the chosen implementation 
regime are essential to verify and refine the model, and will ensure 
that the smolts are actually surviving at the expected level. In 
addition, it will be particularly important to protect the base 
conditions assumed in the model, such as flows during the time the 
Upper Old River barrier is not in place, flows at Jersey Point, and 
temperature.
    The expected criteria index values are unlikely to be achieved if 
these base conditions deteriorate.
    One additional refinement to the implementation measures should be 
considered on the San Joaquin River. As discussed above, the Sacramento 
River criteria include a ceiling value on the maximum salmon smolt 
survival. This was included because there appears to be a point where 
incrementally lower temperatures do not significantly increase salmon 
smolt survival. In theory, there may be a similar point on the San 
Joaquin River where incrementally higher flows in very wet years do not 
yield significantly higher salmon smolt survival. Nevertheless, the 
existing data do not allow quantification of what those flow levels 
are. EPA is supportive of another mechanism for dealing with this 
issue. It is EPA's judgment that in very wet years (those in which the 
flows exceed 10,000 cfs during the relevant period) it may be 
appropriate to meet the flow requirements associated with the targeted 
Fish Migration criteria index solely through natural storm events and 
restricted diversions, and not by upstream reservoir releases. In other 
words, the implementation flows could be provided at these higher flow 
periods by natural hydrology rather than by reservoir releases. In this 
way, the natural ``flood events'' that appear to be so beneficial to 
the salmon would be protected, but the water supply system would not 
have to bear the water costs of generating artificial flood events 
through reservoir releases.

(ii) Use of Continuous Function

    The second principal difference in the final criteria is to state 
the criteria as a ``continuous function'' or ``sliding scale.'' As 
discussed in EPA's alternative formulation of the Fish Migration 
criteria made available in the Notice of Availability, this approach 
replaces the Proposed Rule's statement of the criteria as single fixed 
index values for each of the five water year categories (59 FR 44095). 
The proposed approach did not account for the substantial differences 
in hydrological conditions within water year types. For example, an 
``above normal'' water year type could range from a wet ``above 
normal'' year to a dry ``above normal'' year. Given the extreme 
variation of hydrological conditions in the Bay/Delta, these variations 
within each of the five standard water year types are substantial, and 
should be factored into the calculation of the applicable Fish 
Migration criteria index value. The continuous function approach 
addresses this problem by transforming the five discrete water year 
categories into a more precise equation (graphically, a single line or 
curve) correlating the Fish Migration criteria index value with each 
year's specific observed hydrological conditions. The continuous 
function approach provides the same degree of protection for the 
designated uses as the proposed approach using average survival values. 
However, the continuous function approach provides a more precise 
approximation of hydrological conditions and facilitates implementation 
and compliance. EPA explained the rationale for using the continuous 
function approach in more detail in the technical documents referenced 
in the Notice of Availability (59 FR 44095). The derivations of the 
actual continuous functions for the Sacramento and San Joaquin River 
systems are explained above.

(iii) Measuring Attainment Through Actual Test Results

    The Proposed Rule relied on the criteria index equations to 
determine whether the criteria were being attained. In effect, 
attainment would be assumed if the State adopted an implementation plan 
with a set of measures (export restrictions, flow requirements, etc.) 
that, when computed in the index equations, resulted in the criteria 
index value.
    Many commenters believed that reliance on the criteria index 
equations for this purpose was inappropriate because factors other than 
those implementation measures included in the model may affect smolt 
survival. To address this concern, in the final criteria, direct 
experimental measurements of smolt survival through the Delta will be 
used to estimate attainment of the criteria, instead of relying on 
modeled estimates. Survival is to be measured through tagged smolt 
release and recapture studies. This approach assures that factors 
significantly affecting survival will be reflected in survival 
measurements, even if they are not well described by the criteria index 
equations. This more direct approach gives the State greater latitude 
to develop implementation measures outside of the equation parameters. 
It also ensures that the implementation measures are actually providing 
the intended protection for the Fish Migration designated use.

(3) Fish Migration Criteria as Multispecies Protection

    The Fish Migration criteria outlined above are based on protection 
measures required for a single run of salmon, the fall-run Chinook 
salmon. Some commenters questioned whether this approach conflicts with 
the habitat or multispecies approach recommended by the Club FED 
agencies in their [[Page 4696]] Agreement for Coordination on 
California Bay/Delta Issues signed September 20, 1993. As noted in the 
preamble to the Proposed Rule, EPA believes that the implementation 
measures likely to be adopted to meet the target criteria values in 
these Fish Migration criteria, when combined with the other Federal 
actions in the Delta protecting the endangered winter-run Chinook 
salmon, are fully consistent with the protection of a broad range of 
anadromous and migratory fishes in the Bay/Delta.
    Juvenile spring-run salmon and steelhead move through the Delta 
during the same period as winter-run and fall-run salmon, and are 
expected to be protected in the Delta by measures protecting these 
other runs (CDFG 1990a). Species other than salmon and steelhead 
seasonally migrate into and out of the Delta for spawning and as 
juveniles. These species include striped bass, Delta smelt, longfin 
smelt, white and green sturgeon, American shad and Sacramento 
splittail. With the exception of temperature, the factors that lead to 
successful migration of salmon and steelhead smolts are also important 
for successful migration of the juveniles of these species into the 
lower embayments. Therefore, EPA's proposed Fish Migration criteria, 
although specifically addressing fall-run Chinook salmon, will also 
help protect migration of these other migratory species.

3. Fish Spawning Criteria

a. Proposed Rule
    In California, striped bass spawn primarily in the warmer 
freshwater segments of the Sacramento and San Joaquin Rivers. 
Protection of spawning in both river systems is important to ensure the 
genetic diversity of the population as well as to increase the size of 
the overall striped bass population. The precise location and time of 
spawning appear to be controlled by temperature and salinity (Turner 
1972a; Turner and Chadwick 1972). According to the California DFG, 
striped bass spawn successfully only in freshwater with electrical 
conductivities less than 0.44 millimhos\43\ per centimeter 
electroconductivity (mmhos/cm EC), and prefer to spawn in waters with 
conductivities below 0.33 mmhos/cm. Conductivities greater than 0.55 
mmhos/cm appear to block the upstream migration of adult spawners 
(Radtke and Turner 1967; SWRCB 1988; SWRCB 1991; CDFG 1990b, WQCP-DFG-
4). As explained in more detail in the Preamble to the Proposed Rule, 
salinity does not appear to be a serious limitation on spawning on the 
Sacramento River. However, in the smaller and shallower San Joaquin 
River, migrating bass seeking the warmer waters encounter excessive 
upstream salinity caused primarily by runoff. This salinity can block 
migration up the San Joaquin River, thereby reducing spawning, and can 
also reduce survival of eggs (Farley 1966; Radtke 1966; Radtke and 
Turner 1967; Turner and Farley 1971; Turner 1972a, 1972b).

    \43\Salinity conditions upstream in freshwater are generally 
affected by dissolved salts from upstream water runoff. The salinity 
content of freshwater is traditionally measured by its 
electroconductivity or specific conductance standardized to 
25 deg.C, and is expressed in terms of millimhos per centimeter 
electroconductivity (``mmhos/cm EC'') or micromhos per centimeter 
specific conductance. The Proposed Rule stated the Fish Spawning 
criteria in terms of mmhos/cm EC. In the final rule, EPA will state 
the criteria in terms of micromhos/cm specific conductance, so as to 
be consistent with EPA's published guidance. See 40 CFR Part 136, 
Table 1B--List of Approved Inorganic Test Procedures, Parameter 64. 
The Proposed Rule's term ``0.44 mmhos/cm EC'' is equivalent to the 
final rule's term ``440 micromhos/cm specific conductance''. EPA 
will continue using the ``0.44 mmhos/cm EC'' term in this preamble, 
so as not to confuse the interested public.

                                                 BILLING CODE 6560-50-P
[[Page 4697]]

[GRAPHIC][TIFF OMITTED]TR24JA95.009



BILLING CODE 6560-50-C [[Page 4698]] 
    The State Board's 1991 Bay/Delta Plan established objectives of 1.5 
mmhos/cm EC at Antioch and 0.44 mmhos/cm EC at Prisoners Point in April 
and May. EPA disapproved these objectives, in part, because they are 
not adequate to protect spawning habitat in the reach farther upstream 
between Prisoners Point and Vernalis. EPA also disapproved the 1991 
Bay/Delta Plan spawning criteria because they were not based on sound 
science. The State Board explained that the 1.5 mmhos/cm EC criteria at 
Antioch was intended to protect spawning habitat upstream of Antioch 
(near Jersey Point), not at the Antioch location itself. The State 
Board acknowledged that ``the use of 1.5 [mmhos/cm] EC at Antioch 
appears not to be generally appropriate, and proposed that a thorough 
review of this [criterion] be undertaken at the next triennial review'' 
(1991 Bay/Delta Plan, p. 5-32). EPA found this unproven approach of 
setting criteria downstream in hopes of attaining different criteria 
upstream deficient, and disapproved it.
    In the Proposed Rule (40 CFR 131.37(b)), EPA proposed salinity 
criteria of 0.44 mmhos/cm EC in the lower San Joaquin River in the 
reach from Jersey Point to Vernalis in wet, above normal, and below 
normal water years. In dry and critical water years, EPA proposed the 
0.44 mmhos/cm criteria for only the reach from Jersey Point to 
Prisoners Point.
b. Comments on Proposal and Final Criteria
    EPA received a number of comments on its proposed Fish Spawning 
criteria. California DFG was generally supportive of the proposed 
criteria, but believed that the criteria would need to be supplemented 
by a range of additional management techniques in order to have any 
substantial benefit for spawning (California DFG 1994). Several parties 
noted that striped bass are an introduced predatory species, and that 
efforts to increase striped bass populations would work at cross-
purposes with efforts to enhance other species such as salmon and Delta 
smelt (City and County of San Francisco Public Utilities Commission 
1994; Bay/Delta Urban Coalition 1994; California Farm Bureau Federation 
1994). Other commenters raised the possibility that extending the 
acceptable spawning habitat upstream could result in more striped bass 
being entrained at the State and Federal water project pumps in the 
southern Delta. (California DWR 1994). Finally, some commenters 
believed that emphasizing the striped bass as an individual species was 
inconsistent with the multiple species approach to habitat protection. 
(CUWA 1994a).
    Although EPA believes there is some merit to each of these 
comments, EPA is not making any changes to the Fish Spawning criteria 
in the final rule stated at 40 CFR Sec. 131.37(b). EPA believes there 
is substantial scientific evidence indicating that increased salinities 
in the designated reaches of the San Joaquin River do in fact have an 
adverse effect on fish spawning. This problem of increased salt 
loadings has been recognized by virtually all the parties (CUWA 1994b; 
ACWA 1994) and recommendations on how to address it have been developed 
by, among others, the San Joaquin Valley Drainage Program (SJVDP 1990).
    The possibility that healthier populations of predatory fishes such 
as striped bass would adversely affect other species of concern needs 
to be considered in the context of the whole range of protective 
measures being developed for the fishery. The package of project 
management measures, water quality standards, and implementation 
programs being developed under the CWA, ESA, CVPIA, and counterpart 
State authorities are intended to address the entire Bay/Delta 
ecosystem. For that reason, EPA believes that healthier predatory 
species populations should not interfere with the protection of other 
species of concern. EPA further believes that, if the State Board 
adopts and/or implements these criteria, the State Board can address 
the impact of entrainment at the pumps in its implementation measures. 
Finally, EPA believes that salinity problems in the lower San Joaquin 
affect aquatic species other than the striped bass. Recent research 
findings of USFWS (Meng 1994) suggest that the spawning habitat for the 
Sacramento splittail (currently proposed for listing as threatened 
under the ESA) is also being adversely affected by increased salt 
loadings in the lower San Joaquin. Accordingly, these criteria are 
consistent with a multiple species approach.
    EPA believes that clearly stating the salinity conditions necessary 
for protection of the designated fish spawning uses on the lower San 
Joaquin provides the foundation for implementation plans by the State 
Board and other regulatory agencies. EPA believes that these 
implementation plans should build upon the recommendations of the San 
Joaquin Drainage Program, to the end that compliance with these 
criteria can be effectively and efficiently achieved.
    One change has been made to the final Fish Spawning criteria. In 
the Proposed Rule, the Fish Spawning criteria were stated with 
reference to the five standard water year types, with one criterion 
required for dry and critical dry water years and another criterion 
required for the remaining water year types. In the final rule, 
reliance on water year types is eliminated. Instead, deciding which of 
the two different criteria applies is made by reference to the San 
Joaquin Valley Index, the standard index of San Joaquin Valley flows. 
This change merely eliminates the unnecessary middle step of 
translating the San Joaquin Valley Index into the five water year 
types.

4. Suisun Marsh Criteria

    The tidal wetlands bordering Suisun Bay are characterized as 
brackish marsh because of their unique combination of species typical 
of both freshwater wetlands and more saline wetlands. Suisun Marsh 
itself, bordering Suisun Bay on the north, is the largest contiguous 
brackish water marsh in the United States. These large tidal marshes 
are distinct from the approximately 44,000 acres of ``managed'' marshes 
in the Suisun Bay, which are currently diked and managed for waterfowl 
use and hunting. Approximately 10,000 acres of marshes, both along 
channels within Suisun Marsh and bordering Suisun Bay, are still fully 
tidal (Meiorin et al. 1991).
    These tidal marshes provide habitat for a large, highly diverse, 
and increasingly rare ecological community. The recent ``Status and 
Trends'' reports published by the SFEP listed 154 wildlife species 
associated with the brackish marshes surrounding Suisun Bay (Harvey, et 
al. 1992), including a number of candidates for listing under the ESA. 
These include the Suisun song sparrow (Melospiza melodia maxillaris) 
and the Suisun ornate shrew (Sorex ornatus sinuosus), as well as the 
plants Suisun slough thistle (Cirsium hydrophilum var. hydrophilum), 
Suisun aster (Aster chilensis var. lentus), delta tule pea (Lathyrus 
jepsonii), Mason's lilaeopsis (Lilaeopsis masonii), and soft-haired 
bird's beak (Cordylanthus mollis mollis). These rare species are all 
found exclusively in tidally inundated marsh.
    Recent studies indicate that increases in salinity caused by a 
combination of upstream diversions and drought have adversely affected 
the tidal marsh communities (Collins and Foin 1993). As salinity has 
intruded, brackish marsh plants which depend on soils low in salt 
content (especially the tules Scirpus californicus and S. acutus) have 
died back in both the shoreline marshes and in some interior marsh 
channel margins of the western half of Suisun Bay. These plants have 
been replaced by plants [[Page 4699]] typically growing in saline 
soils, especially cordgrass (Spartina foliosa). This has been 
associated with erosion of the marsh margins. In addition, tules in the 
upper intertidal zone have been replaced by the smaller and more salt 
tolerant alkali bulrush (Scirpus robustus). These changes have 
significantly affected available habitat for a variety of wildlife that 
nest and feed in these areas, including the Suisun song sparrow, marsh 
wren, common yellowthroat, black-crowned night heron, and snowy egret 
(Collins and Foin 1993; Granholm 1987a; 1987b). The loss of habitat for 
the Suisun song sparrow is of particular concern, since individuals of 
this species are found only in the already fragmented marshes bordering 
Suisun Bay, occupy an established territory for their lifetime, and 
depend on tall tules for successful reproduction and cover from 
predators (Marshall 1948).
    There are currently no salinity criteria protecting the brackish 
tidal marshes of Suisun Bay, although there is some incidental 
protection provided by salinity criteria protecting the managed non-
tidal marshes. EPA's approval of the 1978 Delta Plan criteria 
explicitly sought and received assurances from the State Board to 
develop additional criteria for the brackish tidal marshes and to 
protect aquatic life in the Suisun Marsh channels and open waters. 
Because these assurances have not been met, EPA, in its September 3, 
1991 letter on the 1991 Bay/Delta Plan, disapproved the standards for 
Suisun Marsh and stated that the State Board should immediately develop 
salinity objectives sufficient to protect aquatic life and the brackish 
tidal wetlands surrounding Suisun Marsh.
    In its Proposed Rule, EPA relied on the Estuarine Habitat criteria 
to protect the tidal wetlands bordering Suisun Bay, and did not propose 
separate standards in the Suisun Marsh. EPA's proposed criteria were 
developed to protect aquatic species and to provide salinity conditions 
similar to those in the late 1960's to early 1970's. Therefore, many of 
the aquatic species that inhabit the marsh channels would receive 
increased protection once the Estuarine Habitat criteria are 
implemented. In addition, the Estuarine Habitat criteria were designed 
to provide substantially better dry and critically dry year springtime 
conditions than the recent conditions that have caused adverse effects 
on the tidal marsh communities bordering Suisun Bay. EPA therefore 
concluded that these Estuarine Habitat criteria would lead to 
substantially improved conditions in the marshes.
    In its Proposed Rule, EPA solicited comment as to whether the 
Estuarine Habitat criteria should be supplemented by additional 
criteria to fully protect the tidal marsh resources. For illustrative 
purposes, EPA included two possible narrative criteria in the Proposed 
Rule:
    (1) ``water quality conditions sufficient to support high plant 
diversity and diverse wildlife habitat throughout all elevations of the 
tidal marshes bordering Suisun Bay''
    (2) ``water quality conditions sufficient to assure survival and 
growth of brackish marsh plants dependent on soils low in salt content 
(especially Scirpus californicus and Scirpus acutus) in sufficient 
numbers to support Suisun song sparrow habitat in shoreline marshes and 
interior marsh channel margins bordering Suisun Bay.''
    EPA received a number of substantive comments on this issue. The 
State Board and the California DWR opposed additional criteria, 
believing that any such criteria would be premature pending completion 
of a biological assessment in the marsh (SWRCB 1994; California DWR 
1994). The California DFG recommended adoption of the numeric salinity 
criteria included in the Suisun Marsh Preservation Agreement signed by 
California DFG, California DWR, the USBR, and the Suisun Resource 
Conservation District in 1987 (California DFG 1994). Two environmental 
organizations, Natural Heritage Institute and the Bay Institute, 
recommended that additional standards be developed for the Suisun 
Marsh. Relying primarily on scientific studies that had been prepared 
and submitted to the State Board's D-1630 hearings (Jocelyn 1992, 
WRINT-NHI-12; Williams 1992, WRINT-NHI-18), these groups raised 
questions about whether the EPA Estuarine Habitat criteria would 
adequately protect the brackish marshes during January and February, or 
during a multiple year drought, and whether the Estuarine Habitat 
criteria would adequately protect the interior tidal channels of Suisun 
Marsh. In its comments, NHI recommended the adoption of numeric 
salinity criteria (NHI 1994). The Bay Institute recommended adoption of 
narrative criteria for the Marsh, and offered a detailed suggestion.
    EPA believes that the available scientific information points 
strongly to the need for numeric criteria in the tidal marshes. 
Nevertheless, EPA does not believe there exists a sufficient scientific 
basis at this time to support Federal promulgation of numeric criteria 
for these marshes. EPA is hopeful that the biological studies being 
prepared at the request of the State Board will be completed soon, and 
that the State Board will expedite its review of this issue. Given the 
substantial delays in the completion of these studies, however, EPA 
does not believe it advisable to delay addressing the serious 
possibility of adverse impacts to the brackish tidal marshes. For these 
reasons, EPA is incorporating a narrative criterion applicable to the 
tidal (i.e., unmanaged) areas of the Suisun Marsh in the final rule.
    To be consistent with EPA guidance, narrative criteria should 
include specific language about conditions that must exist to protect a 
designated use, and may include specific classes and species of 
organisms that will occur in waters for a given designation (USEPA 
1990). The narrative criterion promulgated below by EPA includes 
language about important measures of biological integrity specific to 
Suisun Bay tidal marshes. Specific reference conditions are not 
included in the criterion; however, it is the intent of this criterion 
to reflect conditions equalling the level of protection existing in the 
Suisun Marsh in the late 1960's to early 1970's. As a result of the 
recent drought and continued high level of freshwater diversion from 
the estuary, recent conditions have deteriorated in the Suisun Marsh, 
as indicated by decreased habitat for the Suisun song sparrow and 
replacement of tules with Spartina foliosa.
    In implementing this narrative criterion, the State Board should 
take care to protect the specific classes and species of organisms that 
are vulnerable to increasing salinity in the Suisun Marsh. Vulnerable 
species include those species that are presently listed under the 
Federal Endangered Species Act, including the salt-marsh harvest mouse 
(Reithrodontomys raviventris) and the California clapper rail (Rallus 
longirostris obsoletus). Vulnerable species also include both those 
rare plants that are candidates for listing under the Federal 
Endangered Species Act (including Mason's lilaeopsis (Lilaeopsis 
masonii), delta tule pea (Lathyrus jepsonii), Suisun slough thistle 
(Cirsium hydrophilum var. hydrophilum), Suisun aster (Aster chilensis 
var. lentus), soft-haired bird's beak (Cordylanthus mollis ssp mollis)) 
and dominant plant species such as the tules Scirpus acutus and S. 
californicus, and the bulrush S. robustus. Animal species include 
Federal candidate species Suisun song sparrow (Melospiza melodia 
maxillaris), California black rail (Laterallus jamaicensis 
coturniculus), tri-colored blackbird (Agelaius tricolor), saltmarsh 
common yellowthroat (Geothylpis trichos sinuosa), Suisun 
[[Page 4700]] ornate shrew (Sorex ornatus sinuosus) and southwestern 
pond turtle (Clemmys marmorata pallida). Other vulnerable species 
include river otter (Lutra canadensis), beaver (Castor canadensis), 
nesting snowy egret (Egretta thula), nesting black-crowned night-heron 
(Nycticorax ncyticorax), ducklings of breeding ducks such as mallard 
(Anas platyrhynchos), gadwall (Anas strepera) and cinnamon teal (Anas 
cyanoptera), marsh wren (Cistothorus palustris), American bittern 
(Botaurus lentiginosus), Virginia rail (Rallus limicola), sora (Porzana 
carolina), and common moorhen (Gallinula chloropus).
    EPA hopes that the measures taken to implement the Estuarine 
Habitat criteria will be sufficient to protect the fish and wildlife 
designated uses targeted by this narrative criterion. Nevertheless, in 
the event that continuing substantial adverse impacts on the brackish 
marsh habitat become evident before any possible revisions to the 
State's numeric criteria, this narrative criterion will provide a basis 
for State Board measures to address those adverse impacts.

D. Public Comments

    Public hearings on the Proposed Rule were held in Fresno, 
California on February 23, 1994; in Sacramento, California on February 
24, 1994; in San Francisco, California on February 25, 1994; and in Los 
Angeles, California on February 28, 1994. Over 120 people spoke at 
these four hearings. The public comment period closed on March 11, 
1994. EPA received over 225 written comments on the Proposed Rule.\44\

    \44\The Bay Institute submitted identical comment letters 
generally supporting adoption of protective standards in the Bay/
Delta from approximately 1,500 people. The total number of comments 
stated in the text counts these comments as a single comment.
---------------------------------------------------------------------------

    Responses to the public comments have been prepared and are a part 
of the administrative record to this rulemaking. The public may inspect 
this administrative record at the place and time described above.

E. Executive Order 12866

    Under Executive Order 12866 (58 FR 51735, October 4, 1993), the 
Agency must determine whether the regulatory action is ``significant'' 
and therefore subject to Office of Management and Budget (OMB) review 
and the requirements of the Executive Order. The Order defines 
``significant regulatory action'' as one that is likely to result in a 
rule that may:
    (1) Have an annual effect on the economy of $100 million or more or 
adversely affect in a material way the economy, a sector of the 
economy, productivity, competition, jobs, the environment, public 
health or safety, or State, local, or tribal governments or 
communities;
    (2) Create a serious inconsistency or otherwise interfere with an 
action taken or planned by another agency;
    (3) Materially alter the budgetary impact of entitlements, grants, 
user fees, or loan programs or the rights and obligations of recipients 
thereof; or
    (4) Raise novel legal or policy issues arising out of legal 
mandates, the President's priorities, or the principles set forth in 
the Executive Order.
    Pursuant to the terms of Executive Order 12866, it has been 
determined that this rule is a ``significant regulatory action'' 
because it raises novel policy issues arising out of the Federal 
coordination effort described above. This coordination effort, which 
calls for the integration of several Federal agencies and several 
different Federal statutes, is a unique and precedential approach to 
the implementation of Federal natural resources policy. As such, this 
action was submitted to OMB for review. Changes made in response to OMB 
suggestions or recommendations will be documented in the public record.
    The following is a summary of the regulatory impact assessment 
(RIA) that has been prepared in compliance with Executive Order 12866. 
The full RIA is part of the administrative record to this rule, and is 
available for public review as described above.
    Executive Order 12866 requires Federal agencies to assess the costs 
and benefits of each significant regulatory action they promulgate. The 
RIA addresses two interrelated regulatory actions. The first is the 
promulgation by EPA of water quality criteria for the Bay/Delta estuary 
under the CWA. The second is the USFWS designation of critical habitat 
for the Delta smelt under the ESA.

Need for Regulation

    The Bay/Delta is the largest estuarine environment on the west 
coast of the Americas, encompassing 1,600 square miles and draining 
more than 40% of the water in California.
     The Bay/Delta estuary supports more than 120 species of 
fish and is a waterfowl migration and wintering area of international 
significance.
     The estuary supports 108 known species of fish, birds, 
mammals, reptiles, amphibians, invertebrates, and plants imperiled by 
habitat loss, including 25 species that are listed or are candidates 
for listing under the Endangered Species Act (ESA).
     The estuary is composed of numerous habitats valued for 
their recreational, scientific, educational, aesthetic, and ecological 
aspects; designated uses defined by the California State Water 
Resources Control Board include estuarine habitat, coldwater and 
warmwater habitat, fish migration, fish spawning, ocean commercial and 
sport fishing, preservation of rare and endangered species, shellfish 
harvesting, and wildlife habitat.
     As a result of habitat change and other human-induced 
impacts, the estuary's ability to support a diverse ecosystem with 
large populations of important commercial, recreational, and heritage 
species has declined. The 1980's and 1990's brought the number of 
indigenous species to extremely low levels. Declines in aquatic 
resources have led to curtailed fishing seasons, petitions for listing 
species under the ESA, and general concern about the health of the 
estuarine ecosystem.
     The principal benefit expected to result from this 
rulemaking is an increase in ecosystem health. A healthy Bay/Delta 
ecosystem will maintain aquatic species in populations of sufficient 
sizes to sustain recreational and commercial fisheries, as well as the 
uniqueness and diversity still present in the estuary.
    The Bay/Delta estuary is also the hub of California's two major 
water distribution systems, the SWP operated by California DWR and the 
CVP operated by the USBR. Most of the water stored and transported by 
the CVP is used for agriculture; the CVP also supplies municipal and 
industrial water to portions of the Central Valley and San Francisco 
Bay Area. SWP water is primarily used for municipal and industrial uses 
and the production of agricultural crops. Development and operation of 
the water projects have contributed to losses in biological 
productivity in the Bay/Delta estuary by substantially altering the 
flow and salinity conditions to which the indigenous organisms are 
adapted.
    The Bay/Delta estuary is subject to the water quality control 
jurisdiction of the State Board and two regional boards. Pursuant to 
requirements of the CWA, the State Board in 1991 adopted and submitted 
to EPA the 1991 Bay/Delta Plan containing water quality standards for 
the Bay/Delta estuary. EPA, finding that the 1991 plan did not provide 
for adequate protection of the designated fish and wildlife uses of the 
Bay/Delta estuary, disapproved provisions of the plan. In response to 
State Board's failure to revise the disapproved criteria, EPA published 
the proposed rule for [[Page 4701]] establishing revised water quality 
criteria; these EPA criteria are the primary subject of the RIA.

Approach

    The RIA analyzes a final rule that establishes four sets of federal 
criteria to protect the designated uses of the Bay/Delta estuary. The 
analysis focuses on the two sets of criteria with measurable water 
costs to Delta exporters:
     Salinity criteria protecting the estuarine habitat, and
     Fish migration criteria to protect fish migration in the 
estuary.
The other two criteria; salinity criteria to protect fish-spawning 
habitat on the lower San Joaquin river and narrative criteria to 
protect tidal wetlands surrounding Suisun Marsh, are not expected to 
result in actions that generate additional economic costs.
    The primary method for implementing the criteria is to increase 
Delta outflow, and the analysis focuses on the effects of this 
approach. EPA recognizes that the State of California has sole 
authority to reallocate water rights in implementing these criteria. 
However, because the State has not yet developed a plan for 
implementation of the criteria, EPA considered the water supply and 
delivery impacts of the criteria using the following three 
implementation approaches that represent the range of options available 
to the State:
     Project Exporters-Only Approach:
    --Generally represents implementation of D-1485, under which the 
SWP and CVP exporters are solely responsible for providing sufficient 
water supplies to attain the water quality criteria.
    --Because of priority systems within the SWP and CVP, would 
concentrate responsibility for meeting the standards on water districts 
with junior water rights, which also bear responsibility for meeting 
requirements associated with the ESA. Municipal and industrial (M&I) 
users are priority users within the SWP system. In the CVP priority 
system, users of 27% of diversions are responsible for meeting 100% of 
the ESA requirements and water quality standards.
    --Could result in effects on San Joaquin Valley agricultural water 
users, primarily in western Fresno and portions of Kern County and the 
urban areas supplied by Metropolitan Water District of Southern 
California (MWD) and Santa Clara Valley Water District (SCVWD).
     Sharing Approach:
    --Would spread water supply impacts to more or potentially all of 
the water districts that divert water from the Sacramento and San 
Joaquin River systems, including areas of the Sacramento Valley, 
eastside San Joaquin Valley and urban areas of San Francisco and East 
Bay.
    --Could be based on formulas using many criteria in assigning 
responsibility, such as diversions, depletions, damage caused by 
diversions, seniority and priority of water rights, beneficial and 
reasonable use, and economics.
    --For the analysis, an illustrative formula was used where 
nonproject diverters and non-exporter CVP users share 20% of 
responsibility for meeting flow requirements necessary to achieve 
compliance with the criteria.
     Other Innovative Approaches:
    --Could include combining shared implementation responsibility with 
a system of mitigation credits, a water supply cap, and a fund or fee 
system for purchasing water for environmental uses; policies for 
promoting a water market and/or a water bank are crucial.

Water Supply and Delivery Impacts

    Short-term (1995) and longer term (2010) impacts of the Project 
Exporters-Only and Sharing Approaches were analyzed through comparison 
with baseline conditions consisting of current conditions that exist in 
the absence of the criteria, estimated for a range of hydrological 
conditions represented in the 71-year hydrologic record for the Delta. 
Water supply costs are commonly reported using two conventions: the 
average of 71 years and the ``critical period'', which represents 
conditions experienced in the drought period of the 1930s.
    The analysis estimated the incremental (i.e. new) water supply and 
delivery impacts of the criteria over those associated with D-1485 and 
the recent (1992-1994) winter-run salmon requirements. These impacts 
reflect the effects of a package of federal actions under several laws 
designed to comprehensively protect the Bay/Delta ecosystem. The entire 
package of actions and requirements have been extensively coordinated 
to achieve significant improvements in the Bay/Delta ecosystem.
    Both the incremental water supply impacts, as well as the recent 
Endangered Species Act impacts can be illustrated in the following 
table:

                                                 BILLING CODE 6560-50-P
[[Page 4702]]

[GRAPHIC][TIFF OMITTED]TR24JA95.010



BILLING CODE 6560-50-C
[[Page 4703]]

    Water delivery impacts are the changes in water volumes available 
to different users and depend on seniority of water rights and priority 
systems within affected water delivery systems, such as the SWP and the 
CVP.

Costs

    The State's implementation plan will substantially affect the 
magnitude and distribution of the costs of regulatory actions. In the 
agricultural sector, economic welfare costs would consist primarily of 
changes in producers' surplus (net operating revenues accruing to 
farmers). In the urban sector, economic welfare costs would take the 
form of consumers' surplus losses to the residential sector resulting 
from developing higher cost replacement supplies and consumer costs of 
water supply shortages. The following are key results of the cost 
analysis:
     Water transfers can greatly reduce impacts on affected 
agricultural and urban areas. Water transfers to urban areas through 
waterbank programs are common and considered likely in the short-run. 
Although, increased agriculture-to-agriculture water transfers are not 
expected in the short-run, they can theoretically decrease impacts 
considerably.
     Urban project contractors water supplies would not be 
affected in most years, even without sharing.
    --MWD's supplies are affected in 11% of years, SCVWD supplies are 
affected in 25% of years.
     With water transfers available in dry years, the cost 
associated with the regulations is estimated to be $4.3 million on 
average and $15.8 million during dry water years for the Project-
Exporters Only scenario. Without water transfers or waterbanks, costs 
increase significantly; the combined cost of water shortages and 
replacement water supplies to project users is estimated to be $28.3 
million on average years and $165.3 million during dry years.
     Agricultural impacts would be small relative to 
agricultural value in the Central Valley but would be concentrated in 
agricultural areas with low-seniority water rights in portions of 
Fresno and Kern counties.
    --Under the Project-Exporters Only scenario and assuming no 
increase in water transfers, economic welfare losses to agriculture are 
estimated to average $27 million annually, weighted over all 
hydrological conditions. However, impacts in the driest 10% of years 
account for economic costs of $43 million.
    --If the State's implementation plan is based solely on seniority 
of water rights and existing contractual arrangements, impacts will be 
concentrated in geographic subareas of Fresno and Kern counties. 
Cumulative impacts are an important consideration in these areas--the 
impacts of environmental requirements associated with the ESA and the 
CVPIA are already concentrated in these subareas. However, the State's 
implementation plan may be based on many criteria, including economics.
     The Sharing Approach would have an important cost-reducing 
effect, especially in dry years if transfers are limited, in comparison 
with the Project Exporters-Only Approach.
    --Economic welfare costs to agriculture would be reduced by sharing 
the responsibility of environmental requirements with all diverters. 
Overall, economic welfare losses would be reduced by approximately $0.5 
million for average years and more than $5.5 million in dry years.
    --A net gain in economic welfare to urban areas would also result 
from sharing. Overall economic losses would be reduced by approximately 
$10.5 million in average years and $54.0 million in dry years when 
transfers are limited.
     Over the long term, costs are not estimated to 
substantially increase, even with increasing demand resulting from 
population growth and decreased groundwater availability.
    A summary of these costs is shown below in RIA Table 2.

             RIA Table 2.--Summary of Economic Welfare Costs            
                        [In millions of dollars]                        
------------------------------------------------------------------------
                                                        Average         
                                                       expected    Dry  
                                                         value    Years 
------------------------------------------------------------------------
Agriculture:\1\                                                         
   No increase in water transfers............        28       43
   Sharing/no increase in transfers..........        27       37
   Increased transfers.......................     10-18       NA
Urban:\2\                                                               
   Dry year transfer.........................         4       16
   No dry year transfer......................        28      165
   Sharing/no dry year transfer..............        18      111
------------------------------------------------------------------------
Note: Total impacts are less than the sum of agricultural and urban     
  impacts in the case of agricultural-to-urban transfers. In cases in   
  which there are no agricultural-to-urban transfer, total impacts equal
  the sum of agricultural and urban impacts.                            
\1\Transfers are from agriculture to agriculture.                       
\2\Transfers are from agriculture to urban users.                       

Benefits

    Important benefits of the water quality regulations include the 
following:
     Biological productivity and health for many estuarine 
species are expected to increase.
     The decline of species is expected to be reversed and the 
existence of species unique to the Bay/Delta, such as Delta smelt, 
winter-run chinook salmon, longfin smelt, and Sacramento splittail, 
will be protected.
     Populations of a variety of estuarine species are expected 
to increase; although the extent of the population increases has not 
been determined for all species, the increases are anticipated to 
benefit the recreational and commercial fisheries.
     Costs associated with further declines in the estuary will 
be avoided. The most important avoided cost is associated with further 
declines in the recreational and commercial fisheries industry 
including further closures affecting the 200 million dollar industry, 
with possible future actions needed to protect species from extinction. 
Other avoided costs include government costs associated with crop 
deficiency payments; agricultural drainage costs; and costs associated 
with potential reductions in property values.
    The ecological benefits of improved Bay/Delta estuary conditions 
are expected to generate approximately $2-21 million annually in net 
economic benefits to commercial and recreational fisheries and have 
associated employment gains of an estimated 145-1,585 full-time 
equivalent jobs annually. The federal package of actions to protect the 
estuary, of which EPA's criteria are a part, will also produce the 
benefit of increased certainty regarding water supplies from the delta; 
this allows for more informed water management planning and 
investments.

Conclusions

    The following general conclusions can be drawn regarding the 
results of the RIA:
     Although urban water supplies are are not affected in most 
years, however, minimizing urban costs largely depend on the 
availability of water through transfers and a drought water bank.
     Under the Project-Exporters Only approach to 
implementation (i.e.,  status-quo), agricultural impacts are 
concentrated only in certain areas of Fresno and Kern Counties. This 
concentration of impacts is magnified by these areas bearing the 
responsibility for Endangered Species requirements. This concentration 
of impacts is the [[Page 4704]] result of historic water rights 
arrangements and may be attenuated through the water rights phase.
     Benefits of ecosystem protection, which could not be 
estimated in the analysis, are expected to substantially exceed the use 
benefits to commercial and recreational fisheries. These nonuse or 
intrinsic values, which include benefits to the public for improved 
ecosystem health and for avoiding the extinction of species and 
closures of fisheries, are difficult to estimate accurately because 
they are nonmarginal.
     Substantial reductions in economic costs--for the same 
level of benefits--resulted from the sharing scenario analysis, 
particularly when transfers are limited. For urban areas, the economic 
benefits of dry year transfers are large, even when compared to the 
benefits of sharing.
     Although a fully developed water market is not likely, it 
could theoretically reduce economic costs to very low levels. 
Innovative implementation plans (purchase funds, fees, tradeable 
responsibility) that take advantage of these potential efficiencies may 
be the most cost-effective solution.
    Given both the monetary estimates and the information on ecological 
benefits that is not calculated in monetary terms, EPA believes that 
the benefits are commensurate with the costs. Cost-effective 
implementation of the criteria will result in a healthy ecosystem and 
fisheries resources coexisting with a strong agricultural sector.

F. Regulatory Flexibility Act

    Under the Regulatory Flexibility Act (5 U.S.C. 601 et seq.) (RFA) 
EPA generally is required to conduct a final regulatory flexibility 
analysis (FRFA) describing the impact of the regulatory action on small 
entities as part of a final rulemaking. However, under section 605(b) 
of the RFA, if EPA certifies that the rule will not have a significant 
economic impact on a substantial number of small entities, EPA is not 
required to prepare a FRFA. Although EPA is providing the certification 
here, it is nevertheless including a discussion for public information 
of possible effects to small entities that could result from State 
Board implementation of today's rule.
    Today's rule establishes ambient water quality criteria that are 
unique in that implementation of these criteria is solely dependent 
upon actions by agencies other than EPA. Until actions are taken to 
implement today's criteria (or equally protective state criteria 
meeting the requirements of the CWA), there will be no economic effect 
of this rule on any entities--large or small. For that reason, and 
pursuant to section 605(b) of the Regulatory Flexibility Act, 5 U.S.C. 
605(b), I hereby certify that this rule itself will not have a 
significant economic impact on a substantial number of small entities.

Discussion

    Although EPA is certifying that this rule will not have a 
significant economic impact on a substantial number of small entities, 
and therefore is not required to prepare a FRFA, it is nevertheless 
presenting this discussion to inform the public of possible economic 
effects of state implementation of the criteria promulgated today on 
small entities. By so doing, EPA intends to inform the public about how 
such entities might be affected by the State's implementation. The 
focus of the discussion is on small farms, and our analysis shows that 
there will be no significant economic effect on a substantial number of 
them. Additionally, as described elsewhere in the RIA, impacts on the 
urban sector, while speculative, are expected to be limited. 
Accordingly, EPA believes there will be no significant economic impact 
on a substantial number of small entities as a result of the State's 
implementation of these criteria.
    This discussion first provides a profile of small entities--in this 
case small farms--to determine whether or not they will be affected by 
State Board actions designed to attain the criteria set forth in this 
rulemaking. EPA investigated information by geographic area using the 
U.S. Small Business Administration's definition. Information used 
includes acreage and gross value per acre.
    Small entities that may be primarily affected by the State's 
implementation of EPA's rule are small farms (as discussed in the RIA, 
the primary economic impacts of implementation of these criteria are 
expected to fall on the agricultural sector; impacts on the urban 
sector are expected to be limited). Small farms are defined by the U.S. 
Small Business Administration as farms with annual sales of less than 
$500,000. Small farms account for 93% of all farms and 53% of all 
cropland (including unharvested pastureland) in California. The 
remaining 7% of California farms, which have annual sales of more than 
$500,000, account for 74% of the value of farm products sold (Jolly 
1993). Unfortunately, no survey information is available by 
subgeographic area and value per operator to assist in determining 
whether or not State Board action implementing this rulemaking could 
affect small farms. As discussed in the RIA, impacts may be 
concentrated in the subgeographic areas of the San Joaquin Valley--
particularly the westside of Fresno County, including Westlands Water 
District and Kern County. This analysis uses the worst case scenarios 
from the RIA in assuming concentrated and, possibly, not insignificant 
impacts in these areas. These assumptions include: no increase in water 
transfers and the most status-quo implementation plan selected by the 
State of California. As discussed in the RIA, innovative implementation 
plans could reduce all agricultural impacts.
    Due to the lack of survey information, two commonly reported 
measures--gross value per acre and acreage per farm--were used to 
develop an indication of whether or not these subgeographic areas 
contain small farms, by the SBA definition. The first commonly reported 
indicator of farm size is acreage.
    EPA used two measures of farm size by acreage in the San Joaquin 
Valley, derived from the 1987 Census of Agriculture. The first measure, 
average farmland per operator, includes the average amounts of 
cropland; rangeland; wooded lands; and lands in buildings, roads, and 
ponds managed by each farm operator in the San Joaquin Valley. The 
average amount of farmland per operator in the San Joaquin Valley is 
341 acres, varying from 266 acres in non-westside areas to 1,834 acres 
in the Westlands Water District. The second measure of farm size, 
irrigated land per operator, includes the average amount of cropland, 
excluding rangelands and wooded lands, managed by each farm operator. 
The average amount of irrigated land per operator in the San Joaquin 
Valley is 165 acres, ranging from 114 acres in non-westside areas to 
1,113 acres in the Westlands Water District. These data suggest that 
some agricultural districts contain very few small farms, while others 
are largely composed of smaller farms.
    These measures of farm size may be distorted by characteristics of 
the data compiled in the 1987 Census of Agriculture. Because of the way 
farm operators are defined and counted within the census, the number of 
truly separate farm operations within the San Joaquin Valley may be 
lower than the census reports. Thus, the amount of farmland and 
irrigated land per separate farm operation is probably higher than 
reported. Additionally, farming is not the principal occupation for 
many farm operators. In the San Joaquin Valley, 44% of the operators 
included in the census reported that farming was not 
[[Page 4705]] their principal occupation (Archibald 1990). These 
operations, which could include hobby farms, are probably much smaller 
than commercial operations. Therefore, the average size of commercial 
operations is likely much larger than reported. These data limitations 
make it difficult to assess the true proportion of the farm industry 
represented by small commercial farms.
    The other measure used to develop an indication of whether or not 
small farms are affected is average gross revenue per acre. This 
information was obtained from the USBR and the same data is used in the 
RIA. As discussed previously, the areas where impacts may be 
concentrated are primarily the westside of the San Joaquin Valley, 
especially Westlands Water District and Kern County. Values of $1100-
$2300 an acre are indicated by this data. These estimates are further 
confirmed by the average value of $1413 an acre found in a recent 
University of California report (Carter 1992.) Thus using the range of 
values for gross revenue per acre and the more conservative definition 
of irrigated land per acre for the Westside, farms average 
approximately $600,000 -$1,120,000. This does not meet the SBA 
definition. In addition, average farm size in the Westlands Water 
District is much larger, leading to average estimates over $1 million 
per operator. In Kern County, however, gross revenue per acre averages 
$1863 and therefore to meet the SBA definition a farm would have to be 
unusually small (under 270 acres.) These estimates indicate that a 
substantial number of small entities would not be substantially 
affected.
    The farms in the CVP area (westside Fresno County) are subject to 
the U.S. Department of Interior 960-acre limitation on farm size for 
the receipt of subsidized water. Although the degree of compliance with 
this limitation is in question, a recent legal settlement by the U.S. 
Department of Interior will increase the enforcement of this acreage 
limitation. Using the measures of average gross revenue per acre, farms 
that approach the acreage limitation are not considered small farms 
using the SBA definition.
    Type of small farm by crop type was also investigated to provide 
another indication of farms potentially affected by State Board action. 
As discussed in the RIA, State Board action consistent with this 
rulemaking would likely result primarily in field and forage crop 
displacement. In 1987, small farms produced 40% of all irrigated hay 
and field crops harvested and 30% of all nonfeedlot cattle sales in the 
state (U.S. Dept. of Commerce 1989). Approximately 80% of the irrigated 
hay and field crops and 50% of nonfeedlot cattle are raised in the 
Sacramento Valley and San Joaquin Valley counties (U.S. Dept. of 
Commerce 1989). Such cattle production is the principal use of 
irrigated pasture in California. These percentages are substantially 
lower than the overall percentage of cropland in small farms. In other 
words, large farms (i.e., farms with annual sales exceeding $500,000) 
account for a disproportionate share of the production of the crops and 
livestock that might be displaced by the projected water supply 
reductions.
    While these measures indicate that the State's implementation of 
the criteria in this rule will not affect a substantial number of small 
farms, given that the measure was developed from averages, there will 
exist in every irrigation district some small farms. Westlands Water 
District reports that 125 farms are 320 acres or less (a 320 acre farm 
grossing $1400-$1500 an acre would meet the SBA definition of a small 
farm.) Thus, without survey information, we cannot completely conclude 
that all small farms would not be affected by State Board action.
    The RIA conducted for this rulemaking indicates that if previous 
implementation procedures are followed, impacts may be concentrated in 
geographic subareas. The State does have implementation flexibility to 
spread the impacts to a greater geographic area. This would have two 
offsetting impacts in relationship to farm size. First, the impacts 
overall will be decreased so that impacts would be less concentrated in 
subregions, possibly to insignificant levels. Second, however, in 
spreading the impacts more broadly, the State will be spreading it to 
areas with small farms.
    Within irrigation districts with project water, junior water rights 
and little access to groundwater, even the State may have little 
implementation authority to assess or minimize impacts by farm size. A 
Stanford University study explains:
    Most farmers receive their water from a local district (generally 
an irrigation, water, or water storage district) or from a mutual water 
company * * * local districts have considerable discretion over the 
acquisition, allocation and pricing of water. The nature and limits of 
the discretion, however, vary among districts depending on the laws 
under which the district was formed, any special legislation unique to 
a district, and a district's local rules and regulations. (Center for 
Economic Policy Research 1992.)

G. Enhancing the Intergovernmental Partnership Under Executive 
Order 12875

    In compliance with Executive Order 12875, 58 FR 58093 (October 28, 
1993), we have involved state, local, and tribal governments in the 
development of this rule. In addition to the substantial participation 
by state and local governments and local agricultural and municipal 
water districts in the public commenting process, several activities 
have been carried out since the publication of the Proposed Rule. These 
include:
    (1) The State of California and the Federal government (represented 
by the EPA, the Department of the Interior, and the Department of 
Commerce) have negotiated and this past summer signed a Framework 
Agreement laying out the institutional processes and mechanisms to be 
used to coordinate state and Federal activities affecting water quality 
and water development in the Bay/Delta. The Framework Agreement 
specifically included (a) a process for Federal and state adoption of 
water quality standards meeting the requirements of state and Federal 
law, (b) a structure and process for technical coordination of the 
state and Federal regulatory activities affecting operation of the 
state and Federal water projects in the Bay/Delta (the SWP and the 
CVP), and (c) a process for developing a Federal-state partnership for 
long term planning for water resources in California. Many of the steps 
envisioned in the Framework Agreement have already been accomplished. 
The Framework Agreement explicitly called for the final Federal 
promulgation of a water quality rule, which is being accomplished in 
this rulemaking.
    (2) EPA has held a number of workshops with representatives of the 
municipal and agricultural water districts to discuss the Proposed Rule 
and the accompanying draft economic analysis. Further, EPA has 
participated in additional workshops sponsored by the California Urban 
Water Agencies (CUWA) to discuss CUWA's scientific comments on the 
Proposed Rule.
    (3) As envisioned by the Framework Agreement, the State Board has 
held a series of workshops to assist in developing revised State water 
quality standards meeting the requirements of the CWA. EPA has 
participated in these workshops and, in accordance with the State 
Board's processes, has presented the State Board options for possible 
standards that would meet the requirements of the CWA.
    (4) EPA has worked closely with the California DWR to ascertain the 
[[Page 4706]] probable water supply impacts of its Proposed Rule, and 
has continued to work with California DWR to explore mechanisms for 
reducing water supply impacts of protective standards. As explained in 
the Preamble to the final rule, many of these mechanisms have been 
incorporated into EPA's final rule.
    (5) EPA has worked closely with representatives of a coalition of 
CUWA and of agricultural water agencies to consider alternative 
standards and measures that would meet the requirements of the CWA.
    (6) EPA has continued to meet with the State Board and other State 
officials, both at the staff and policy levels, to discuss ways to 
attain protection of the Bay/Delta resources in a way that meets the 
requirements of the CWA and is consistent with the State's roles in 
water quality and water development planning.

H. Paperwork Reduction Act

    This rule places no information collection activities on the State 
of California and, therefore, no information collection request (ICR) 
will be submitted to the Office of Management and Budget (OMB) for 
review in compliance with the Paperwork Reduction Act, 44 U.S.C. 3501 
et seq.

References in the Preamble

    Archibald, S. 1990. Economic profile of agriculture in the west 
side of the San Joaquin Valley.
    Arthur, J.F., and M.D. Ball, 1979. Factors influencing the 
entrapment of suspended materials in the San Francisco Bay/Delta 
Estuary. In: San Francisco Bay: The Urbanized Estuary, R.J. Conomos 
(ed.). Pacific Div., American Assoc. for the Advancement of Science, 
San Francisco, California, pp. 143-174.
    Association of California Water Agencies, 1994. Comments of the 
Association of California Water Agencies on water quality standards 
for the Bay/Delta dated July 13, 1994. 22 pp.
    Bay Institute, 1994. Comments on the proposed Rule for Water 
Quality Standards in the Bay/Delta, 1 p., plus three appendices and 
three enclosures.
    Bay/Delta Urban Coalition, 1994. Letter from Steering Committee 
to P. Wright dated March 4, 1994. 4 pp., plus large comment book.
    Brandes, P., 1994. Development of a Refined San Joaquin Delta 
Salmon Smolt Model. Draft Report, May 31, 1994. 7 pp. plus 
attachments.
    California Department of Fish and Game, 1990a. Central Valley 
Salmon and Steelhead Restoration and Enhancement Plan. 115 pp.
    California Department of Fish and Game, 1990b. Testimony of 
Department for Fish and Game. WQCP-DFG-4.
    California Department of Fish and Game, 1992a. Water quality and 
water quantity needs for chinook salmon production in the Upper 
Sacramento River. Prepared for the California SWRCB Interim Water 
Rights Decision on the San Francisco Bay/Sacramento-San Joaquin 
Delta Estuary. WRINT-DFG-14.
    California Department of Fish and Game, 1992b. Summary and 
Recommendations for the Department of Fish and Game's Testimony on 
the Sacramento-San Joaquin Estuary. WRINT-DFG-8.
    California Department of Fish and Game, 1994. Comments on the 
Water Quality Standards for the Bay and Delta, 6 pp., plus 1 p. 
comment attachment.
    California Department of Water Resources, 1993. Biological 
Assessment for South Delta Temporary Barriers Project for USFWS 
Section 7 Endangered Species Permit. Amendment 1. Office of 
Environmental Services. March 1993. 35 pp.
    California Department of Water Resources, 1994. Comments on the 
Water Quality Standards for the Bay and Delta, 2 pp., plus 88+ pp. 
comment booklet and 7 appendices.
    California Farm Bureau Federation, 1994. Letter from B. Vice to 
C. Browner dated April 8, 1994. 2 pp., plus attachments.
    California State Lands Commission, 1991. Delta-Estuary: 
California's Inland Coast, A Public Trust Report, 208 pp.
    California Urban Water Agencies, 1994a. Comments on the Water 
Quality Standards for the Bay and Delta dated March 9, 1994. 3 pp., 
plus 5 pp. supplementary comments and 12 draft technical appendices.
    California Urban Water Agencies, 1994b. Recommendations to the 
State Water Resources Control Board for a coordinated estuarine 
protection program for the San Francisco Bay-Sacramento and San 
Joaquin River Delta Estuary, August 25, 1994. 46 pp. plus 2 
appendices.
    Carter, H., and G. Goldman, 1992. The Measure of California 
Agriculture. University of California. Oakland, California.
    Center for Economic Policy Research, 1992. An Economic Analysis 
of Water Availability in California Central Valley Agriculture, 
Phase III Draft Report. Stanford, California.
    City & County of San Francisco Public Utilities Commission, 
1994. Letter from A. Moran to P. Wright dated March 11, 1994. 2 pp., 
plus attachments.
    Collins, J.N. and T.C. Foin, 1993. Evaluations of the Impacts of 
Aqueous Salinity on the Shoreline Vegetation of Tidal Marshlands in 
the San Francisco Estuary. In: SFEP, Managing Freshwater Discharge 
to the San Francisco Bay-Delta Estuary: The Scientific Basis for an 
Estuarine Standard. Appendix C.
    Contra Costa Water District, 1994. Comments on the Water Quality 
Standards for the Bay and Delta, 5 pp., plus 2 attachments.
    Denton, R.A., 1993. Accounting for Antecedent Conditions in 
Seawater Intrusion Modeling--Applications for the San Francisco Bay/
Delta Hydraulic Engineering 93, vol. 1, pp. 448-453.
    Denton, R.A., 1994. Minor Modifications to the G-Model Fit of 
Electrical Conductivity Versus Antecedent Outflow. Internal CCWD 
report, 8 pp.
    Five Agency Delta Salmon Team, 1991a. Evaluation of the 
Feasibility of Protecting Downstream Migrant Chinook Salmon Smolts 
in the Sacramento River and San Joaquin River with Physical 
Facilities, July 15, 1991.
    Five Agency Delta Salmon Team, 1991b. Benefit/Cost Evaluations 
of Alternative Salmon Protective Measures in the Sacramento-San 
Joaquin Delta. Draft Report. March 13, 1991. 101 pp.
    Farley, T.C., 1966. Striped bass, Roccus saxatilis, spawning in 
the Sacramento San Joaquin River systems during 1963 and 1964. DFG 
Fish Bull. 136 pages 28-43.
    Ferriera, I. and H. Meyer, 1994. WRMI Presentation at the 
Sliding Scale Workshop, April 14, 1994, 1 p.
    Granholm, S.L., 1987a. Special-status wildlife species of the 
Suisun Bay tidal marshes, and expected impacts of reduced freshwater 
inflows. Sierra Club Legal Defense Fund Exhibit 4, SWRCB San 
Francisco Bay/Delta Hearings.
    Granholm, S.L., 1987b. Expected impacts of reduced freshwater 
inflows on representative birds and mammals of the Suisun Bay tidal 
marshes. Sierra Club Legal Defense Fund Exhibit 5, SWRCB San 
Francisco Bay/Delta Hearings.
    Harvey, T.E., K.J. Miller, R.L. Hothem, M.J. Rauzon, G.W. Page, 
R.A. Keck, 1992. Status and Trends Report on Wildlife of the San 
Francisco Estuary. January 1992.
    Herbold, B., A.D. Jassby, P.B. Moyle, 1992. San Francisco 
Estuary Project Status and Trends Report on Aquatic Resources in the 
San Francisco Estuary. March 1992. 257 pp.
    Jocelyn, M., 1992. Adverse effects of increased salinity in the 
Suisun Marsh Brackish wetlands. WRINT-NHI-12. 6 pp.
    Jolly, 1993. ``The small farm: It's innovative and persistent in 
a changing world'', 47 California Agriculture No. 2. University of 
California, Oakland, California.
    Kimmerer, W., 1994a. A sliding scale for the EPA salinity 
standard. 12 p.
    Kimmerer, W., 1994b. Setting Goals for Salmon Smolt Survival in 
the Delta and Discussions on the Proposed EPA Salinity Standard. 
August 10, 1994. 28 pp.
    Kjelson, M., S. Green & P. Brandes, 1989. A Model for Estimating 
Mortality and Survival of Fall-run Chinook Salmon Smolts in the 
Sacramento River Delta between Sacramento and Chipps Island.
    Marshall, J.T., Jr., 1948. Ecologic races of song sparrows in 
the San Francisco Bay region, Part I. Habitat and abundance. Condor 
50(5) 193-215.
    Meiorin, E.C., M.N. Josselyn, R. Crawford, J. Calloway, K. 
Miller, R. Pratt, T. Richardson and R. Leidy, 1991. Status and 
Trends Report on Wetlands and Related Habitats in the San Francisco 
Estuary. San Francisco Estuary Project, December 1991.
    Meng, L., 1994. Status Report on Sacramento splittail and 
longfin smelt. Unpublished report submitted to USFWS August 25, 
1994. 15 pp. plus attachments.
    Monismith, S.J., 1993. A note on the physical significance of 
X2. IESP Newsletter, June 1993.
    Moyle, P.B. and R.M. Yoshiyama, 1992. Fishes, Aquatic Diversity 
Management Areas, and Endangered Species: A Plan to Protect 
California's Native Aquatic Biota. University of California. 
California Policy Seminar Report. 222 pp. [[Page 4707]] 
    Natural Heritage Institute, 1994. Comments on the proposed rule 
for water quality standards in the Bay/Delta, 1 p., plus 42+ pp. of 
comments and Attachments A-F.
    Radtke, L.D., 1966. Distribution and abundance of adult and 
subadult striped bass Roccus saxatilis, in the Sacramento-San 
Joaquin Delta. DFG Fish Bulletin 136 pages 15-27.
    Radtke, L.D. and J.L. Turner, 1967. High concentrations of total 
dissolved solids block spawning migration of striped bass, Roccus 
saxatilis, in the San Joaquin River, California. Transactions of the 
American Fisheries Society 96:405-407.
    San Francisco Estuary Project, 1992. State of the Estuary: A 
Report on Conditions and Problems in the San Francisco Bay/
Sacramento-San Joaquin Delta Estuary. 270 pp.
    San Francisco Estuary Project, 1993. Managing Freshwater 
Discharge to the San Francisco Bay/Sacramento-San Joaquin Delta 
Estuary: The Scientific Basis for an Estuarine Standard. 17 pp. + 
appendices.
    San Joaquin Valley Drainage Program, 1990. A Management Plan for 
Agricultural Subsurface Drainage and Related Problems on the 
Westside San Joaquin Valley. 183 pp.
    SWRCB, 1987. Phase I Hearing Transcript, Volume XLI, 68:1-69:10. 
December 22, 1987.
    SWRCB, 1988. Draft Water Quality Control Plan for Salinity, San 
Francisco Bay/Sacramento-San Joaquin Delta Estuary. October 1988.
    SWRCB, 1991. Water Quality Control Plan for Salinity, San 
Francisco Bay/Sacramento-San Joaquin Delta Estuary. 91-15WR, May 
1991.
    SWRCB, 1994. Comments on the Water Quality Standards for the Bay 
and Delta, 2 pp., plus 63+ pp. comments attachment.
    Turner, J.L., 1972a. Striped bass spawning in the Sacramento and 
San Joaquin Rivers in Central California. Calif. Fish Game 62:106-
118.
    Turner, J.L., 1972b. Striped Bass in Ecological Studies of the 
Sacramento-San Joaquin Delta Estuary, DFG Delta Fish and Wildlife 
Protection Report 8 pages 36-43.
    Turner, J.L. and H.K. Chadwick, 1972. Distribution and abundance 
of young-of-year striped bass (Morone saxatilis) in relation to 
river flow in the Sacramento-San Joaquin Estuary. Transactions 
American Fisheries Society 101(3):442-452.
    Turner, J.L. and T.C. Farley, 1971. Effects of temperature, 
salinity, and dissolved oxygen on the survival of striped bass eggs 
and larvae. Calif. Fish and Game 57:268-273.
    U.S. Department of Commerce, 1989. 1987 Census of Agriculture, 
Volume 1, Geographic Area Series, Part 5, California State and 
County Data.
    USEPA, 1990. Biological Criteria: National Program Guidance for 
Surface Waters. EPA-440/5-90-004, April 1990.
    USFWS, 1992a. Measures to improve the protection of chinook 
salmon in the Sacramento/San Joaquin River Delta. WRINT-USFWS-7. 
Expert testimony of U.S. Fish and Wildlife Service on chinook salmon 
technical information for State Water Resources Control Board Water 
Rights Phase of the Bay/Delta Proceedings, July 6, 1992.
    USFWS, 1992b. Abundance and survival of juvenile chinook salmon 
in the Sacramento-San Joaquin Estuary. WRINT-USFWS-9. 1991 Annual 
Progress Report. Sacramento-San Joaquin Estuary Fishery Resource 
Office, U.S. Fish and Wildlife Service, Stockton, Calif. June, 1992.
    USFWS, 1992c. Expert testimony of United States Fish and 
Wildlife Service on recommendations for interim protection and 
response to hearing notice key issues for State Water Resources 
Control Board Water Rights Phase of the Bay-Delta Estuary 
Proceedings, July 6, 1992. WRINT-USFWS-8.
    Williams, P., 1992. Management of Salinity in Suisun Bay. WRINT-
NHI-18. 3+ pp.

List of Subjects in 40 CFR Part 131

    Environmental protection, Indians--lands, Intergovernmental 
relations, Reporting and recordkeeping requirements, Water pollution 
control, Water quality standards, Water quality criteria.

    Dated: December 14, 1994.
Carol M. Browner,
Administrator.
    40 CFR part 131 is amended as follows:

PART 131--[AMENDED]

    1. The authority citation for part 131 continues to read as 
follows:

    Authority: 33 U.S.C. 1251 et seq.

    2. Section 131.37 is added to read as follows:


Sec. 131.37  California.

    (a) Additional criteria. The following criteria are applicable to 
waters specified in the Water Quality Control Plan for Salinity for the 
San Francisco Bay/Sacramento-San Joaquin Delta Estuary, adopted by the 
California State Water Resources Control Board in State Board 
Resolution No. 91-34 on May 1, 1991:
    (1) Estuarine habitat criteria. (i) General rule. (A) Salinity 
(measured at the surface) shall not exceed 2640 micromhos/centimeter 
specific conductance at 25  deg.C (measured as a 14-day moving average) 
at the Confluence of the Sacramento and San Joaquin Rivers throughout 
the period each year from February 1 through June 30, and shall not 
exceed 2640 micromhos/centimeter specific conductance at 25  deg.C 
(measured as a 14-day moving average) at the specific locations noted 
in Table 1 near Roe Island and Chipps Island for the number of days 
each month in the February 1 to June 30 period computed by reference to 
the following formula:

Number of days required in Month X = Total number of days in Month X * 
(1-1/(1+eK)
where K = A + (B*natural logarithm of the previous month's 8-River 
Index);
A and B are determined by reference to Table 1 for the Roe Island and 
Chipps Island locations;
x is the calendar month in the February 1 to June 30 period;
and e is the base of the natural (or Napierian) logarithm.

Where the number of days computed in this equation in paragraph 
(a)(1)(i)(A) of this section shall be rounded to the nearest whole 
number of days. When the previous month's 8-River Index is less than 
500,000 acre-feet, the number of days required for the current month 
shall be zero.
    Table 1. Constants applicable to each of the monthly equations to 
determine monthly requirements described.

----------------------------------------------------------------------------------------------------------------
                                                           Chipps Island             Roe Island (if triggered)  
                     Month X                     ---------------------------------------------------------------
                                                         A               B               A               B      
----------------------------------------------------------------------------------------------------------------
Feb.............................................            -\1\            -\1\          -14.36          +2.068
Mar.............................................         -105.16         +15.943          -20.79          +2.741
Apr.............................................          -47.17          +6.441          -28.73          +3.783
May.............................................          -94.93         +13.662          -54.22          +6.571
June............................................          -81.00          +9.961         -92.584        +10.699 
----------------------------------------------------------------------------------------------------------------
\1\Coefficients for A and B are not provided at Chipps Island for February, because the 2640 micromhos/cm       
  specific conductance criteria must be maintained at Chipps Island throughout February under all historical 8- 
  River Index values for January.                                                                               

    (B) The Roe Island criteria apply at the salinity measuring station 
maintained by the U.S. Bureau of Reclamation at Port Chicago (km 64). 
The Chipps Island criteria apply at the Mallard Slough Monitoring Site, 
Station [[Page 4708]] D-10 (RKI RSAC-075) maintained by the California 
Department of Water Resources. The Confluence criteria apply at the 
Collinsville Continuous Monitoring Station C-2 (RKI RSAC-081) 
maintained by the California Department of Water Resources.
    (ii) Exception. The criteria at Roe Island shall be required for 
any given month only if the 14-day moving average salinity at Roe 
Island falls below 2640 micromhos/centimeter specific conductance on 
any of the last 14 days of the previous month.
    (2) Fish migration criteria. (i) General rule.
    (A) Sacramento River. Measured Fish Migration criteria values for 
the Sacramento River shall be at least the following:

At temperatures less than below 61 deg.F: SRFMC = 1.35
At temperatures between 61 deg.F and 72  deg.F: SRFMC = 6.96-.092 * 
Fahrenheit temperature
At temperatures greater than 72  deg.F: SRFMC = 0.34

where SRFMC is the Sacramento River Fish Migration criteria value. 
Temperature shall be the water temperature at release of tagged salmon 
smolts into the Sacramento River at Miller Park.
    (B) San Joaquin River. Measured Fish Migration criteria values on 
the San Joaquin River shall be at least the following:

For years in which the SJVIndex is > 2.5: SJFMC = (-0.012) + 
0.184*SJVIndex
In other years: SJFMC = 0.205 + 0.0975*SJVIndex

where SJFMC is the San Joaquin River Fish Migration criteria value, and 
SJVIndex is the San Joaquin Valley Index in million acre feet (MAF)
    (ii) Computing fish migration criteria values for Sacramento River. 
In order to assess fish migration criteria values for the Sacramento 
River, tagged fall-run salmon smolts will be released into the 
Sacramento River at Miller Park and captured at Chipps Island, or 
alternatively released at Miller Park and Port Chicago and recovered 
from the ocean fishery, using the methodology described in this 
paragraph (a)(2)(ii). An alternative methodology for computing fish 
migration criteria values can be used so long as the revised 
methodology is calibrated with the methodology described in this 
paragraph (a)(2)(ii) so as to maintain the validity of the relative 
index values. Sufficient releases shall be made each year to provide a 
statistically reliable verification of compliance with the criteria. 
These criteria will be considered attained when the sum of the 
differences between the measured experimental value and the stated 
criteria value (i.e., measured value minus stated value) for each 
experimental release conducted over a three year period (the current 
year and the previous two years) shall be greater than or equal to 
zero. Fish for release are to be tagged at the hatchery with coded-wire 
tags, and fin clipped. Approximately 50,000 to 100,000 fish of smolt 
size (size greater than 75 mm) are released for each survival index 
estimate, depending on expected mortality. As a control for the ocean 
recovery survival index, one or two groups per season are released at 
Benecia or Pt. Chicago. From each upstream release of tagged fish, fish 
are to be caught over a period of one to two weeks at Chipps Island. 
Daylight sampling at Chipps Island with a 9.1 by 7.9 m, 3.2 mm cod end, 
midwater trawl is begun 2 to 3 days after release. When the first fish 
is caught, full-time trawling 7 days a week should begin. Each day's 
trawling consists of ten 20 minute tows generally made against the 
current, and distributed equally across the channel.
    (A) The Chipps Island smolt survival index is calculated as:

SSI=RMT(0.007692)

where R=number of recaptures of tagged fish
M=number of marked (tagged) fish released
T=proportion of time sampled vs total time tagged fish were passing the 
site (i.e. time between first and last tagged fish recovery)

Where the value 0.007692 is the proportion of the channel width fished 
by the trawl, and is calculated as trawl width/channel width.
    (B) Recoveries of tagged fish from the ocean salmon fishery two to 
four years after release are also used to calculate a survival index 
for each release. Smolt survival indices from ocean recoveries are 
calculated as:

OSI=R1/M1R2/M2

where R1=number of tagged adults recovered from the upstream 
release
M1=number released upstream
R2=number of tagged adults recovered from the Port Chicago release
M2=number released at Port Chicago

    (1) The number of tagged adults recovered from the ocean fishery is 
provided by the Pacific States Marine Fisheries Commission, which 
maintains a port sampling program.
    (2) [Reserved]
    (iii) Computing fish migration criteria values for San Joaquin 
River. In order to assess annual fish migration criteria values for the 
San Joaquin River, tagged salmon smolts will be released into the San 
Joaquin River at Mossdale and captured at Chipps Island, or 
alternatively released at Mossdale and Port Chicago and recovered from 
the ocean fishery, using the methodology described in paragraph 
(a)(2)(iii). An alternative methodology for computing fish migration 
criteria values can be used so long as the revised methodology is 
calibrated with the methodology described below so as to maintain the 
validity of the relative index values. Sufficient releases shall be 
made each year to provide a statistically reliable estimate of the 
SJFMC for the year. These criteria will be considered attained when the 
sum of the differences between the measured experimental value and the 
stated criteria value (i.e., measured value minus stated value) for 
each experimental release conducted over a three year period (the 
current year and the previous two years) shall be greater than or equal 
to zero.
    (A) Fish for release are to be tagged at the hatchery with coded-
wire tags, and fin clipped. Approximately 50,000 to 100,000 fish of 
smolt size (size greater than 75 mm) are released for each survival 
index estimate, depending on expected mortality. As a control for the 
ocean recovery survival index, one or two groups per season are 
released at Benicia or Pt. Chicago. From each upstream release of 
tagged fish, fish are to be caught over a period of one to two weeks at 
Chipps Island. Daylight sampling at Chipps Island with a 9.1 by 7.9 m, 
3.2 mm cod end, midwater trawl is begun 2 to 3 days after release. When 
the first fish is caught, full-time trawling 7 days a week should 
begin. Each day's trawling consists of ten 20 minute tows generally 
made against the current, and distributed equally across the channel.
    (B) The Chipps Island smolt survival index is calculated as:

SSI=RMT(0.007692)

where R=number of recaptures of tagged fish
M=number of marked (tagged) fish released
T=proportion of time sampled vs total time tagged fish were passing the 
site (i.e. time between first and last tagged fish recovery)

Where the value 0.007692 is the proportion of the channel width fished 
by the trawl, and is calculated as trawl width/channel width.
    (C) Recoveries of tagged fish from the ocean salmon fishery two to 
four years after release are also used to calculate a survival index 
for each release. Smolt survival indices from ocean recoveries are 
calculated as:

[[Page 4709]] OSI=R1/M1  R2/M2
where R1=number of tagged adults recovered from the upstream 
release
M1=number released upstream
R2=number of tagged adults recovered from the Port Chicago release
M2=number released at Port Chicago

    (1) The number of tagged adults recovered from the ocean fishery is 
provided by the Pacific States Marine Fisheries Commission, which 
maintains a port sampling program.
    (2) [Reserved]
    (3) Suisun marsh criteria. (i) Water quality conditions sufficient 
to support a natural gradient in species composition and wildlife 
habitat characteristic of a brackish marsh throughout all elevations of 
the tidal marshes bordering Suisun Bay shall be maintained. Water 
quality conditions shall be maintained so that none of the following 
occurs: Loss of diversity; conversion of brackish marsh to salt marsh; 
for animals, decreased population abundance of those species vulnerable 
to increased mortality and loss of habitat from increased water 
salinity; or for plants, significant reduction in stature or percent 
cover from increased water or soil salinity or other water quality 
parameters.
    (ii) [Reserved]
    (b) Revised criteria. The following criteria are applicable to 
state waters specified in Table 1-1, at Section (C)(3) (``Striped 
Bass--Salinity : 3. Prisoners Point--Spawning) of the Water Quality 
Control Plan for Salinity for the San Francisco Bay--Sacramento/San 
Joaquin Delta Estuary, adopted by the California State Water Resources 
Control Board in State Board Resolution No. 91-34 on May 1, 1991:

--------------------------------------------------------------------------------------------------------------------------------------------------------
                    Sampling site Nos (I--                                                            San Joaquin                                       
     Location               A/RKI)             Parameter         Description         Index type      Valley Index         Dates              Values     
--------------------------------------------------------------------------------------------------------------------------------------------------------
San Joaquin River   D15/RSAN018,           Specific.........  14-day running     Not Applicable...  >2.5 MAF        April 1 to May 31  0.44 micro-mhos. 
 at Jersey Point,   C4/RSAN032,            Conductance......   average of mean                                                                          
 San Andreas        D29/RSAN038,           @ 25  deg.C......   daily for the                                                                            
 Landing,           P8/RSAN056,                                period not more                                                                          
 Prisoners Point,   -/RSAN062,                                 than value                                                                               
 Buckley Cove,      C6/RSAN073,                                shown, in mmhos.                                                                         
 Rough and Ready    C7/RSAN087,                                                                                                                         
 Island, Brandt     C10/RSAN112                                                                                                                         
 Bridge, Mossdale,                                                                                                                                      
 and Vernalis.                                                                                                                                          
San Joaquin River   D15/RSAN018,           Specific           14-day running     Not Applicable...  2.5  April 1 to May 31  0.44 micro-mhos. 
 at Jersey Point,   C4/RSAN032,             Conductance.       average of mean                       MAF                                                
 San Andreas        D29/RSAN038                                daily for the                                                                            
 Landing and                                                   period not more                                                                          
 Prisoners Point.                                              than value                                                                               
                                                               shown, in mmhos.                                                                         
--------------------------------------------------------------------------------------------------------------------------------------------------------

    (c) Definitions. Terms used in paragraphs (a) and (b) of this 
section, shall be defined as follows:
    (1) Water year. A water year is the twelve calendar months 
beginning October 1.
    (2) 8-River Index. The flow determinations are made and are 
published by the California Department of Water Resources in Bulletin 
120. The 8-River Index shall be computed as the sum of flows at the 
following stations:
    (i) Sacramento River at Band Bridge, near Red Bluff;
    (ii) Feather River, total inflow to Oroville Reservoir;
    (iii) Yuba River at Smartville;
    (iv) American River, total inflow to Folsom Reservoir;
    (v) Stanislaus River, total inflow to New Melones Reservoir;
    (vi) Tuolumne River, total inflow to Don Pedro Reservoir;
    (vii) Merced River, total inflow to Exchequer Reservoir; and
    (viii) San Joaquin River, total inflow to Millerton Lake.
    (3) San Joaquin Valley Index. (i) The San Joaquin Valley Index is 
computed according to the following formula:

ISJ=0.6X+0.2Y and 0.2Z
where ISJ=San Joaquin Valley Index
X=Current year's April-July San Joaquin Valley unimpaired runoff
Y=Current year's October-March San Joaquin Valley unimpaired runoff
Z=Previous year's index in MAF, not to exceed 0.9 MAF

    (ii) Measuring San Joaquin Valley unimpaired runoff. San Joaquin 
Valley unimpaired runoff for the current water year is a forecast of 
the sum of the following locations: Stanislaus River, total flow to New 
Melones Reservoir; Tuolumne River, total inflow to Don Pedro Reservoir; 
Merced River, total flow to Exchequer Reservoir; San Joaquin River, 
total inflow to Millerton Lake.
    (4) Salinity. Salinity is the total concentration of dissolved ions 
in water. It shall be measured by specific conductance in accordance 
with the procedures set forth in 40 CFR 136.3, Table 1B, Parameter 64.

[FR Doc. 95-817 Filed 1-23-95; 8:45 am]
BILLING CODE 6560-50-P