[Federal Register Volume 65, Number 12 (Wednesday, January 19, 2000)]
[Notices]
[Pages 2954-2956]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-1211]


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ENVIRONMENTAL PROTECTION AGENCY

[FRL-6526-3]


Water Quality Criteria: Notice of Draft Ambient Water Quality 
Criteria for Dissolved Oxygen (Saltwater): Cape Cod to Cape Hatteras

AGENCY:  Environmental Protection Agency (EPA).

ACTION:  Notice of availability of Draft Ambient Water Quality Criteria 
for Dissolved Oxygen (Saltwater): Cape Cod to Cape Hatteras.

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SUMMARY:  Pursuant to section 304(a)(1) of the Clean Water Act (CWA), 
the Environmental Protection Agency announces the availability of a 
draft document titled, Draft Ambient Water Quality Criteria for 
Dissolved Oxygen (Saltwater): Cape Cod to Cape Hatteras. The EPA is 
considering using the values presented in this document as its 
recommended national 304(a) criteria for dissolved oxygen in saltwater. 
These 304(a) criteria would provide recommended guidance values for 
States, Territories, and authorized Tribes to use in adopting water 
quality criteria to protect aquatic life from acute and chronic effects 
of low dissolved oxygen. Under the CWA, States, Territories, and Tribes 
are to adopt water quality criteria to protect designated uses. As the 
document is currently written, these water quality criteria would apply 
only to the Virginian Province (Cape Cod to Cape Hatteras), but with 
appropriate modifications, they may be applicable to other regions. 
While these criteria would constitute EPA's scientific recommendations 
regarding ambient concentrations of dissolved oxygen that protect 
saltwater aquatic life, these criteria are not regulations; thus they 
would not impose legally binding requirements on EPA, States, 
Territories, Tribes, or the public, and might not apply to a particular 
situation based upon the circumstances. State, Territories, and 
authorized Tribes retain the discretion to adopt, where appropriate, 
other scientifically defensible water quality standards that differ 
from these recommendations. EPA may change these 304(a) criteria in the 
future.
    These draft criteria were under development prior to the Agency's 
revision and implementation of its current processes for notice of data 
availability and criteria development (see Federal Register, December 
10, 1998, 63 FR 68354 and in the EPA document titled, National 
Recommended Water Quality--Correction EPA 822-Z-99-001, April 1999). As 
indicated in the December 10, 1998 FR document, the Agency believes it 
is important to provide the public with an opportunity to submit 
scientific information on draft criteria, even though we are not 
required to invite nor respond to specific issues. Therefore, EPA will 
review and consider significant scientific information submitted by the 
public that might not have otherwise been identified during development 
of these criteria, or in the external peer review. The external peer 
review comments and EPA's responses are available in the Water Docket. 
After review of the submitted significant scientific information, EPA 
will publish a revised document, or publish a document indicating its 
decision not to revise the document.
    This draft document has been approved for publication by the Office 
of Science and Technology, Office of Water, U.S. Environmental 
Protection Agency. Mention of trade names or commercial products does 
not constitute endorsement or recommendation for use.

DATES:  All significant scientific information must be submitted to the 
Agency within 45 days after publication of this document in the Federal 
Register under docket number W-99-22. The Administrative Record 
supporting this guidance document, including results of the peer review 
is available at the Water Docket, Room EB-57, Environmental Protection 
Agency, 401 M Street SW, Washington, DC 20460 on Monday through Friday, 
excluding Federal holidays, between 9:00 a.m. and 4:00 p.m. For access 
to docket materials call (202) 260-3027 for an appointment. A 
reasonable fee will be charged for photocopies. Any scientific 
information submitted should be adequately documented and contain 
enough supporting information to indicate that acceptable and 
scientifically defensible procedures were used and that the results are 
likely reliable.

ADDRESSES:  Copies of the complete document, titled Draft Ambient Water 
Quality Criteria for Dissolved Oxygen (Saltwater): Cape Cod to Cape 
Hatteras can be obtained from EPA's Water Resource Center by phone at 
202-260-7786, or by e-mail to [email protected]  or by 
conventional mail to EPA Water Resource Center, RC-

[[Page 2955]]

4100, 401 M Street SW, Washington, DC 20460. Alternatively, consult 
www.epa.gov/OST/standards/ for download availability.
    An original and two copies of written significant scientific 
information should be submitted within 45 days after publication in the 
Federal Register, and addressed to W-99-22, Saltwater Dissolved Oxygen 
Criteria Clerk; Water Docket (MC-4101), U.S. EPA, 401 M Street SW, 
Washington, DC 20460. Issues may be submitted electronically in ASCII 
or Word Perfect 5.1, 5.2, 6.1, or 8.0 formats to [email protected].

FOR FURTHER INFORMATION CONTACT:  Erik L. Winchester, USEPA, Health and 
Ecological Criteria Division (4304), Office of Science and Technology, 
401 M Street, SW, Washington, DC 20460; or call (202) 260-6107; fax 
(202) 260-1036; or e-mail [email protected].

SUPPLEMENTARY INFORMATION:

Introduction

    Section 304(a)(2) of the CWA calls for information on the 
conditions necessary ``to restore and maintain biological integrity of 
all * * * waters, for the protection and propagation of shellfish, fish 
and wildlife, to allow recreational activities in and on the water, and 
to measure and classify water quality.'' The EPA has not previously 
issued saltwater criteria for dissolved oxygen (D.O.) because, until 
recently, the available effects information was insufficient. This 
draft document is the result of a research effort to produce sufficient 
information to support the development of saltwater D.O. criteria. The 
draft water quality criteria presented herein represent EPA's best 
estimates, based on the data available, of D.O. concentrations 
necessary to protect aquatic life and uses associated with aquatic 
life.

Overview of the Problem

    EPA's Environmental Monitoring and Assessment Program (EMAP) for 
the estuaries in the Virginian Province (defined as Cape Cod to Cape 
Hatteras) has shown that 25% of the area of the Province is exposed to 
some degree to D.O. concentrations less than 5 mg/L. EMAP also has 
generated field observations that correlate many of the biologically 
degraded benthic areas with low D.O. in the lower water column. These 
two reports serve to emphasize that low D.O. (hypoxia) is a major 
concern within the Virginian Province. Hypoxia is defined in this 
document as the reduction of D.O. concentrations below air saturation. 
Even though hypoxia is a major concern, a strong technical basis for 
developing benchmarks for low D.O. effects has been lacking until 
recently.
    In the Virginian Province, hypoxia is essentially a warm water 
phenomenon. In the southern portions of the Province, such as the 
Chesapeake Bay and its tributaries, reduced D.O. may occur any time 
between May and October; in the more northern coastal and estuarine 
waters, it may occur at any time from late June into September. Hypoxic 
events can occur on seasonal or diel (daily) time scales. Seasonal 
hypoxia often develops as a consequence of water column stratification, 
which prevents mixing of well oxygenated surface water with deeper 
water. Diel cycles of hypoxia often occur in non-stratified shallow 
habitats where nighttime respiration temporarily depletes D.O. Hypoxia 
may also persist more or less continuously over a season (with or 
without a cyclic component) or be episodic (i.e., of irregular 
occurrence and indefinite duration). The fauna most at risk from 
hypoxic exposure in the Virginian Province are primarily summer 
inhabitants of subpycnocline (i.e., bottom) waters.

Biological Effects of Low Dissolved Oxygen

    Oxygen is essential in aerobic organisms for the electron transport 
system of mitochondria. Oxygen insufficiency at the mitochondria 
results in reduction in cellular energy and a subsequent loss of ion 
balance in cellular and circulatory fluids. If oxygen insufficiency 
persists, death will ultimately occur, although some aerobic animals 
also possess anaerobic metabolic pathways, which can delay lethality 
for short time periods (minutes to days). The animals most sensitive to 
hypoxia are those inhabiting well oxygenated environments.

Overview of the Protection Approach

    The approach to determine D.O. criteria to protect saltwater 
animals within the Virginian Province takes into account both 
continuous (i.e., persistent) and cyclic (e.g., diel, tidal, or 
episodic) exposures to low D.O. The continuous situation considers 
exposure durations of 24 hours or greater. Criteria for cyclic 
situations would cover hypoxic exposures of less than 24 hours, but 
which may be repeated over a series of days. Both scenarios cover three 
areas of protection (summarized here, and explained in more detail in 
the document):
    (1) Protection for juvenile and adult survival,
    (2) Protection for chronic (growth) effects, and
    (3) Protection for larval recruitment effects (estimated with a 
generic model).
    The approach to derive these draft water quality criteria combines 
features of traditional water quality criteria with a new biological 
framework that integrates time (replacing the concept of an averaging 
period) and establishes separate protection limits for different life 
stages (i.e., larvae versus juveniles and adults). Where practical, 
data were selected and analyzed in manners consistent with the 
Guidelines for Deriving Numerical National Water Quality Criteria for 
the Protection of Aquatic Organisms and Their Uses (hereafter referred 
to as the Guidelines).
    With the three areas of protection in mind, the draft saltwater 
D.O. criteria segregate effects on juveniles and adults from those on 
larvae. The survival data on the sensitivity of the former are handled 
in a traditional Guidelines manner. The cumulative effects of low D.O. 
on larval recruitment to the juvenile life stage, on the other hand, 
would address survival effects on larvae. In the draft document the 
recommended approach for deriving D.O. criteria uses a mathematical 
model to evaluate the effect of D.O. conditions on larvae by tracking 
intensity and duration effects across the larval recruitment season. 
Protection for larvae of all species is provided by using data for a 
sensitive aquatic organism (larval stage of the Say mud crab, 
Dyspanopeus sayi). The model is used to generate a draft D.O. criterion 
for larval survival as a function of time.
    For the reasons listed above, the recommended draft D.O. criteria 
approach deviates somewhat from EPA's traditional approach for toxic 
chemicals outlined in the Guidelines. However, where practical, data 
selection and analysis procedures are consistent with the Guidelines. 
Although most of the terminology and the calculation procedures are the 
same, knowledge of the Guidelines is useful for a more complete 
understanding of how these draft D.O. criteria are derived.
    The draft juvenile/adult survival and the growth criteria would 
provide useful screening boundaries within which to judge the D.O. 
status of a given site. If the D.O. conditions are above the chronic 
growth criterion (4.8 mg/L), then this site would meet objectives for 
protection. If the D.O. conditions are below the juvenile/adult 
survival criterion (2.3 mg/L), then this site would not meet objectives 
for protection. When the D.O. conditions are between these two values, 
then the site would require evaluation, using the model, of duration 
and intensity of hypoxia to determine

[[Page 2956]]

suitability of habitat for the larval recruitment objective.
    The draft D.O. criteria are based entirely on laboratory findings. 
However, field observations support the findings of laboratory studies. 
Field acute effects occurred in juvenile and adult animals at 2.0 mg/L, 
which would be predicted based on the 2.3 mg/L juvenile/adult 
criterion. In the field, behavioral effects generally occurred within 
the range where many of the laboratory sublethal effects occurred. 
However, an important limitation of using field observations to 
describe D.O. protection is the absence of field observations on the 
survival and growth of hypoxic sensitive larvae. This type of 
information is critical since two of the three goals for protection are 
derived from responses of larvae.

Implementation Overview

    Implementation of draft D.O. criteria may be slightly different 
from that of chemical toxicants, but not for reasons associated with 
either biological effects or exposure. The primary reason that D.O. 
might be implemented differently from toxic compounds is because 
controlling the effects of low D.O. is not accomplished by directly 
regulating D.O. Rather, hypoxia is a symptom of a problem, not the 
direct problem. Thus dissolved oxygen would be regulated primarily 
through the control of nutrients (e.g., nitrogen and phosphorus) and 
oxygen demanding wastes. As a stressor, D.O. also differs from most 
toxic compounds in that there can be a large natural component to the 
cause of hypoxic conditions in any given water body. Dissolved oxygen 
criteria may be appropriately used in a risk assessment framework. The 
draft criteria and management approach presented in this document could 
be used to compare D.O. conditions among areas and determine if D.O. 
conditions would be adequate to support aquatic life. Environmental 
managers could determine which sites need the most attention, and what 
is the spatial and temporal extent of hypoxic problems from one year to 
the next. Finally, environmental planners could use the draft approach 
to evaluate how conditions would improve under different management 
scenarios, helping them make better management decisions.

Limitations of the Document

    The geographic scope of the draft criteria are limited to the 
Virginian Province of the Atlantic coast of the United States (i.e., 
southern Cape Cod, MA, to Cape Hatteras, NC). The draft document 
provides the necessary information for environmental planners and 
regulators within the Virginian Province to address the question: are 
the D.O. conditions at a given site sufficient to protect coastal or 
estuarine aquatic life? The approach outlined in the draft document 
could be used to evaluate existing localized D.O. standards or 
management goals or establish new ones. The draft criteria do not 
address direct behavioral responses (i.e., avoidance) or the ecological 
consequences of behavioral responses, such as increased or decreased 
predation rates or altered community structure, nor do they address the 
issue of spatial significance of a D.O. problem. In addition, as with 
all criteria, the draft criteria do not account for changes in 
sensitivity to low D.O. that accompany other stresses, such as high 
temperature, extremes of salinity, or toxicants. Chief among these 
concerns would be high temperature because high temperature and low 
D.O. often appear together. Low D.O. would be more lethal at water 
temperatures approaching the upper thermal limit for species. The 
limits provided in the draft document should be sufficient under most 
conditions where aquatic organisms are not otherwise unduly stressed.
    The draft criteria for the Virginian Province may be over- or 
under-protective of aquatic life in other regions. However, the 
approach used to develop the draft criteria is considered to be 
applicable to other regions with appropriate regional modifications. 
Organism adaptations to lower oxygen requirements may have occurred in 
locations where oxygen concentrations have historically been reduced 
due to high temperatures, or in systems with non-anthropogenic high 
oxygen demand. Conversely, organisms in another region could be adapted 
to colder temperature and higher dissolved oxygen regimes than those 
covered in the document, and thus may have different sensitivity to 
dissolved oxygen concentrations. In addition, effects of hypoxia may 
vary latitudinally, or site-specifically, particularly as reproductive 
seasons determine exposure risks for sensitive early life stages. For 
these reasons, an environmental risk manager would be to carefully 
evaluate water quality and biological conditions within the specific 
location and decide if the Virginian Province criteria would apply or 
if region- or site-specific considerations would need to be made.

Endangered or Threatened Species Policy Recommendations

    When a threatened or endangered species occurs at a site and 
sufficient data indicate that it is sensitive at concentrations below 
the recommended criteria, it would be appropriate to consider deriving 
a site-specific criterion.

Future Addendum and Applications

    In addition to publishing this document, an addendum will be 
published in the near future that will specifically address 
implementation issues. In the current draft document, implementation 
issues are discussed in a more general manner, summarizing important 
issues that environmental managers should consider in adopting and 
implementation of D.O. water quality standards. The addendum will 
provide a more detailed discussion of implementation issues by using 
real world example data sets. Application of this guidance to marine 
waters outside the Virginian Province will also be discussed. As a 
component of the addendum, EPA will also publish a computer program 
that will allow Sates and other users to calculate D.O. criteria values 
for coastal and estuarine animals. The program will be based on the 
models discussed in the criteria document and will contain a graphic 
user interface. EPA anticipates publication of the Addendum and 
computer model to occur sometime in 2000.
    EPA believes the approach used to develop the draft criteria can be 
applied, with minor modifications and regional specific data, to derive 
D.O. criteria for other coastal and estuarine regions of the United 
States. Therefore, in the future, EPA plans to prepare similar D.O. 
criteria for other provinces based on this approach. At such time, EPA 
will publish a Notice of Data Availability and formally request 
submission of data from parties interested in the development of D.O. 
criteria for other provinces.

    Dated: January 10, 2000.
Geoffrey H. Grubbs,
Director, Office of Science and Technology.
[FR Doc. 00-1211 Filed 1-18-00; 8:45 am]
BILLING CODE 6560-50-P