[Federal Register Volume 71, Number 36 (Thursday, February 23, 2006)]
[Notices]
[Pages 9336-9337]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E6-2557]


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ENVIRONMENTAL PROTECTION AGENCY

[FRL-OW-8035-9]


Notice of Availability of Final Recommended Aquatic Life Ambient 
Water Quality Criteria for Diazinon

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notice of availability.

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SUMMARY: The Environmental Protection Agency (EPA) announces the 
availability of final recommended aquatic life ambient water quality 
criteria for diazinon. The Clean Water Act (CWA) requires EPA to 
develop and publish, and from time to time revise, recommended criteria 
for water accurately reflecting the latest scientific knowledge. These 
criteria provide EPA's recommendations to states and authorized tribes 
as they establish their water quality standards as state or tribal law 
or regulation. An EPA ambient water quality criterion does not 
substitute for EPA regulations, nor is it a regulation. It does not 
impose legally binding requirements on the EPA, states, authorized 
tribes or the regulated community. State and tribal decision makers 
have discretion to adopt approaches that differ from EPA's guidance.

ADDRESSES: Copies of the criteria document entitled, Ambient Aquatic 
Life Water Quality Criteria for Diazinon--Final (EPA-822-F-05-001) may 
be obtained from EPA's Water Resource Center by phone at (202) 566-
1729, or by e-mail to [email protected] or by conventional 
mail to: EPA Water Resource Center, 4101T, 1200 Pennsylvania Avenue, 
NW., Washington, DC 20460. You can also download the document from 
EPA's Web site at http://www.epa.gov/waterscience/criteria/diazinon/.

FOR FURTHER INFORMATION CONTACT: Rick Stevens, U.S. EPA, Office of 
Water, Health and Ecological Criteria Division (4304T), 1200 
Pennsylvania Avenue, NW., Washington, DC 20460; (202) 566-1135; 
[email protected].

SUPPLEMENTARY INFORMATION:

I. General Information

A. Interested Entities

    Entities potentially interested in today's notice are those that 
produce, use, or regulate diazinon. Categories and entities interested 
in today's notice include:

------------------------------------------------------------------------
                                               Examples of interested
                 Category                             entities
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State/Local/Tribal Government.............  Water Quality Officials.
Insecticide Producers.....................  U.S. and International
                                             Chemical Companies.
Insecticide Users.........................  Growers of fruit, vegetable,
                                             nut, and ornamental crops.
------------------------------------------------------------------------

    This table is not intended to be exhaustive, but rather provides a 
guide for readers regarding entities likely to be interested in this 
notice. This table lists the types of entities that EPA is aware could 
potentially be interested in this notice. Other types of entities not 
listed in the table could also be interested.

B. How Can I Get Copies of This Document and Other Related Information?

    1. Docket. EPA has established an official public docket for the 
diazinon final recommended ambient aquatic life water quality criteria 
under Docket ID No. OW-2003-0062. The official public docket also 
consists of the draft criteria document, and scientific views received. 
Although a part of the official docket, the public docket does not 
include Confidential Business Information (CBI) or other information 
whose disclosure is restricted by statute. Publicly available docket 
materials are available either electronically through http://www.regulations.gov or in hard copy at the Water Docket in the EPA 
Docket Center, (EPA/DC) EPA West, Room B102, 1301 Constitution Ave., 
NW., Washington, DC. The EPA Docket Center Public Reading Room is open 
from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding legal 
holidays. The telephone number for the Public Reading Room is (202) 
566-1744, and the telephone number for the Water Docket is (202) 566-
2426. To view these documents and materials, please call ahead to 
schedule an appointment. Every user is entitled to copy 266 pages per 
day before incurring a charge. The Docket may charge 15 cents a page 
for each page over the 266-page limit plus an administrative fee of 
$25.00.
    2. Electronic Access. You may access this Federal Register document 
electronically through the EPA Internet under the Federal Register 
listings at http://www.epa.gov/fedrgstr/.

II. Background and Today's Notice

A. What Are Recommended Ambient Water Quality Criteria?

    An EPA recommended water quality criterion is a level of a 
pollutant or other measurable substance in water that, when met, will 
protect aquatic life and/or human health. Section 304(a) of the Clean 
Water Act (CWA) requires EPA to develop and publish and, from time to 
time, revise recommended water quality criteria to accurately reflect 
the latest scientific knowledge. Water quality criteria developed under 
section 304(a) provide guidance to states and tribes in adopting water 
quality criteria into their water quality standards under section 
303(c). Once adopted by a state or tribe, the water quality standards 
then are a basis for developing regulatory controls on the discharge or 
release of pollutants. EPA's section 304(a) criteria also provide a 
scientific basis for EPA to develop any necessary federal water quality 
regulations under section 303(c) of the CWA.
    The recommended criteria in today's notice are based on the factors 
specified in section 304(a) of the Clean Water Act, including the kind 
and extent of effects of the pollutant on human health and aquatic 
organisms. EPA's recommended criteria are used by states and tribes in 
developing their regulatory criteria under section 303(c) of the CWA. 
Under the Clean Water Act, regulatory criteria must protect the 
designated use, independent of the economic and technical feasibility 
of meeting the criteria. Economic and technical feasibility factors are 
considered by states and tribes when they adopt designated uses into 
their water quality standards under section 303(c) of the Act and when 
states, tribes, and EPA consider variance requests for regulatory 
controls. Moreover, states and tribes may also consider alternative 
scientifically-defensible approaches to adopting criteria into their 
water quality standards.

B. What Is Diazinon and Why Are We Concerned About It?

    Diazinon is an organophosphorus pesticide traditionally used 
throughout the U.S. to control insects in agricultural areas, 
households and urban settings. However, as of December 31, 2004, all 
residential uses of diazinon products in the United States have been 
phased out or cancelled.
    Diazinon is mobile and moderately persistent in the environment. 
Due to its chemical properties and widespread

[[Page 9337]]

use, diazinon is frequently found in effluents from wastewater 
treatment plants and in storm water runoff in both urban and 
agricultural areas. Diazinon is toxic to aquatic life, particularly 
invertebrates. For these reasons, EPA has developed aquatic life 
ambient water quality criteria to protect against adverse effects of 
diazinon.

C. What Are the National Recommended Water Quality Criteria for 
Diazinon?

Freshwater
    Aquatic life should not be affected unacceptably if the:
    One-hour average concentration of diazinon does not exceed 0.17 
micrograms per liter more than once every three years on the average 
(Acute Criterion), and
    Four-day average concentration of diazinon does not exceed 0.17 
micrograms per liter more than once every three years on the average 
(Chronic Criterion).
Saltwater
    Aquatic life should not be affected unacceptably if the:
    One-hour average concentration of diazinon does not exceed 0.82 
micrograms per liter more than once every three years on the average 
(Acute Criterion), and
    Four-day average concentration of diazinon does not exceed 0.82 
micrograms per liter more than once every three years on the average 
(Chronic Criterion).

D. Why Is EPA Notifying the Public About the Final Diazinon Ambient 
Water Quality Criteria?

    On December 31, 2003, EPA notified the public that draft aquatic 
life criteria for diazinon were available and solicited scientific 
views on those criteria (68 FR 75555). Based on data and information 
submitted, EPA revised the draft criteria and is now making the final 
aquatic life criteria recommendations. While these criteria 
recommendations do not, in themselves, impose any requirements, states 
and authorized tribes can use them to develop water quality standards.

E. What New Data and Changes Have Been Included in the Final Criteria 
Recommendations?

    New data on the toxicity of diazinon to the invertebrate species, 
Gammarus pseudolimnaeus, were submitted to EPA during the comment and 
scientific view period (Hall and Anderson 2004). These new data were 
reviewed per EPA's Guidelines for deriving numerical national water 
quality criteria for the protection of aquatic organisms and their uses 
(Stephan et al., 1985) and found to be acceptable. These data were 
included in the data set used to derive the final acute freshwater 
criteria in Table 1 of the final criteria document.
    Comparison of the new data for the Gammarus pseudolimnaeus to 
existing data for another species in the genus Gammarus (Gammarrus 
faciatus) showed a range in sensitivity between the two species in the 
genus. Furthermore, the apparent sensitivity of Gammarus faciatus was 
notably greater than other invertebrate species. Based on these 
findings, EPA requested a review of the original G. faciatus toxicity 
test data by the U.S. Geological Survey's (USGS) laboratory where the 
original testing was conducted. The USGS review of the Gammarus 
faciatus toxicity test documentation revealed that the acute toxicity 
values reported for the test, both in the original publication (Johnson 
and Finley, 1980) and in a subsequent compilation publication (Mayer 
and Ellersick, 1986) were in error. The USGS advised EPA, in writing, 
that the acute LC50 for Gammarus faciatus should be reported as 2.0 
micrograms per liter, not as 0.2 micrograms per liter (Ingersoll, 
2004). This correction in the acute toxicity LC50 for Gammarus faciatus 
is included in Table 1 of EPA's final criteria document.
    The addition of the new toxicity data for Gammarus pseudolimnaeus 
and the change to the toxicity data for Gammarus faciatus result in a 
change in the genus mean acute value (GMAV) for Gammarus from 0.2 
micrograms per liter to 5.8 micrograms per liter (see Table 1 and 3 in 
the final criteria document). The new data and correction also change 
the rank order of the GMAVs (Gammarus GMAV rank changes from 1 to 4) 
and, ultimately, the final recommended acute freshwater criteria value, 
from 0.10 micrograms per liter to 0.17 micrograms per liter.
    Based on scientific views received and additional internal review, 
EPA also changed the final chronic saltwater criterion. In the draft 
criteria document, the saltwater Final Chronic Value (FCV), derived 
using the procedures outlined in the Guidelines, was 0.82 micrograms 
per liter. However, the saltwater FCV value was lowered to the Species 
Mean Chronic Value (SMCV) of the sheepshead minnow on the basis of it 
being a commercially or recreationally important species. EPA received 
scientific views indicating that while sheepshead minnow is an 
ecologically important species, it is not recognized as recreationally 
or commercially important. Consideration of these views resulted in 
EPA's conclusion that use of the SMCV as the basis of the saltwater 
criterion is unwarranted. Thus, the final saltwater species four-day 
average concentration of diazinon is based on the Final Chronic Value 
calculated by dividing the Final Acute Value (1.64 micrograms per 
liter) by the Final Acute-Chronic Ratio (2.0). Reconsideration of the 
sheepshead minnow data changes the final recommended chronic saltwater 
criteria value from 0.40 micrograms per liter to 0.82 micrograms per 
liter.

References

Hall, L.W. and R.D. Anderson. 2004. Acute Toxicity of Diazinon to the 
Amphipod, Gammarus pseudolimnaeus. University of Maryland, Agricultural 
Experiment Station, Queenstown, MD.
Ingersoll, C. 2004. Diazinon toxicity data for Gammarus fasciatus 
reported in Johnson and Finley (1980) and in Mayer and Ellersieck 
(1986). Letter dated October 5, 2004 from U.S. Department of the 
Interior to E.V. Ohanian, U.S. Environmental Protection Agency, 
Washington, DC.
Johnson, W.W. and M.T. Finley. 1980. Handbook of acute toxicity of 
chemicals to fish and aquatic invertebrates. Resource Publication 137. 
U.S. Fish and Wildlife Service, Washington, DC.
Mayer, F.L. Jr. and M.R. Ellersick, 1986. Manual of acute toxicity: 
Interpretation and data base for 410 chemicals and 66 species of 
freshwater animals. Resource Publication No. 160, U.S. Fish and 
Wildlife Service, Washington, DC.
Stephan, C.E., D.I. Mount, D.J. Hansen, J.H. Gentile, G.A. Chapman and 
W.A. Brungs. 1985. Guidelines for deriving numerical national water 
quality criteria for the protection of aquatic organisms and their 
uses. PB85-227049. National Technical Information Service, Springfield, 
VA.

    Dated: February 15, 2006.
Ephraim S. King,
Director, Office of Science and Technology.
 [FR Doc. E6-2557 Filed 2-22-06; 8:45 am]
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