1. Whole Effluent Toxicity NPDES Program Laura Phillips USEPA - Office of Wastewater Management 202-564-0741, phillips.laura@epa.gov

2. What is Whole Effluent Toxicity (WET) Testing & Why Do it? • What is it? - WQ-based toxics control method that directly measures the total or aggregate toxic effect (additive, synergistic and antagonistic) of an aqueous sample through the response(s) of exposed aquatic organisms. • Why do it? - Protects Narrative Criterion (“no toxics in toxic amounts”) & was designed to predict the impact and toxicity of effluents to determine “safe effluent discharge concentrations” with respect to WQS (criteria).

3. EPA Whole Effluent Toxicity (WET) Program WET - Component of the WQ Integrated Approach • WQ WET Criteria & Standards • NPDES Regulations: 40 CFR Part 122 (i.e., 40 CFR Part 122.44(d)(1)(iv) & (v)) • WET Methods (40 CFR Part 136) • NPDES Permit & EPA Regions, Permitting Authorities (45 NPDES States) and Permittees • Consultants (i.e., Labs)

4. Narrative - “no toxics in toxic amounts” Numeric - TSD recommendations or numeric interpretation of Narrative Acute = 0.3 TUa (e.g., 100/LC50) Chronic = 1.0 TUc (e.g., 100/NOEC) Applying toxicity criteria with allowable dilution 1.0 TUc Outfall 0.3 TUa Whole Effluent Toxicity Criteria

5. Major Components of a NPDES Permit • Cover Page • Effluent limitations • Monitoring & Reporting Requirements • Special Conditions • Standard Conditions

6. With Regard to WET - - NPDES Permits Must Specify • Test Species and Method (Fathead Minnow, Acute or Chronic) • Testing Frequency (Representative of the Effluent) • Statistical Endpoints (Acute: LC50 or IWC, Chronic: NOEC, ICp) • Steps to Address Toxicity (Accelerated WET testing, TREs/TIEs)

7. WET Test Method Selection • Approved acute and chronic methods (40 CFR Part 136) • Must determine: • Acute or chronic toxicity (based on calculated limits or available dilution) • Freshwater or marine discharge • Most appropriate species (e.g., 3 species quarterly for 1 year)

8. WET Monitoring • WET Monitoring Representative of Effluent Discharge:Important for WET reasonable potential determinations & evaluating WET NPDES permit limit compliance • USEPA NPDES Regulations:  40 CFR 122.21(g)(11)  40 CFR Part 122.21(j)(5)  40 CFR Part 122.44 (i)  40 CFR Part 122.48 (b) • USEPA Guidance: • Technical Support Document (TSD) (1991, OWM) • Interim Guidance for Performance-Based Reductions of NPDES Monitoring Frequencies (4/19/96, OW/OECA)

9. WET Reasonable Potential (RP) Determinations • No WET Data:Use EPA Technical Support Document’s (TSD) statistical approaches to determine if RP exists. • Fewer than ten valid WET data points (per species):EPA’s TSD provides recommended coefficients of variation. • Ten or more valid WET data points: With ten or more valid and representative effluent data points a robust WET RP determination can be done.

10. TSD Steps in Developing WET Permit Limitations WLA = Wasteload Allocation, LTA= Long Term Average Acute & Chronic Wasteload Allocations Step 1: Convert Acute WLA to Chronic WLA (WET only) Step 2: Calculate LTA for Both Step 3: Select Lowest LTA Step 4: Calculate Maximum Daily Load & Average Monthly Limits

11. NPDES Program Resources • USEPA OWM Catalog of Publications (EPA 830/B-96-001) • Basic Permit Writers’ Manual (EPA/833-B-96-003, 12/96) • Technical Support Document (EPA/505-2-90-001, 3/91) • USEPA Basic Permit Writer’s Course - Ca (1/03) OWM Web site: http://cfpub1.epa.gov/npdes or E-mail: pwcourse@cadmusgroup.com • SETAC WET Training Courses Web site: setac.org

12. NPDES Program Resources Under Development • NPDES Permit Development Tool (NPDES/PDT): Electronic tool that will allow permit writers to interactively calculate water quality-based effluent limitations for large number of pollutants. Future versions will include the ability to calculate technology-based limits. • Permit Application Software System (PASS): Phase I: Electronic system which allows permittees to electronically prepare NPDES permit applications, print, & mail it to their NPDES permitting authorities. Phase II: System will be enhanced to allow electronic submission to the NPDES permitting authority. (http://cfpub.epa.gov/npdes/pass)

13. WET National Program Technical Resources Information/Assistance: • EPA OW/OWM Web site: http://cfpub.epa.gov/npdes • EPA OW/OST Web site: www.epa.gov/waterscience/WET • EPA Regional Contacts • SETAC Web site: www.setac.org/wetindex.html including “Frequently Asked Questions” Bulletin Board • SETAC WET Expert Advisory Panel: www.setac.org • USEPA WET Document Compendium

14. USEPA WET Document Compendium - Sample List • WET Requirements in Municipal Permits (7/85) • WET Sample Permitting & Enforcement Guidance (2/89) • WET Control Policy (7/94) • National Policy Regarding WET Enforcement (8/95) • Clarifications Regarding Flexibility in WET Methods (4/96) • Clarifications Regarding WET Test Methods & Guidance on Implementing WET Toxicity in Permits (7/97) • TRE Municipal Guidance (8/99) • WET Variability Guidance (6/00) • WET Test Methods Guidance (7/00) • TRE/TIE Clarifications Document (5/01) • WET Test Methods Proposed Rule (9/01)

15. Where Do We Go From Here? • Critical Crossroads - Require careful consideration of the issues, maintaining the NPDES base program, & identifying possibilities for appropriate flexibility within existing NPDES regs and the CWA. • Review the Facts - Use facts to cull out non-productive issues so remaining issues are prioritized in a manner that produces results. • Pursue Strategic Pathways or Decisions - To overcome ongoing barriers to effectively implementing the NPDES WET program.

16. Closing Remarks Move Program Forward Where possible, reduce controversies and implement the WET program in a manner that fulfills CWA objectives, complies with USEPA NPDES regulations, and is endorsed by stakeholders through their actions and support to the program.