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

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).

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)

Whole Effluent Toxicity Criteria Applying toxicity criteria with allowable dilution 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) Outfall 0.3 TUa 1.0 TUc

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

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)

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)

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)

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.

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

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

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)

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

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)

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.

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.