Whole Effluent Toxicity (WET) Testing

Aquatic Life Toxicity Testing Methods Manual

WET Guidance Document

Where to Get More WET Information

Wastewater Discharge Permits

The Latest Revisions to the WET Guidance Document

July 2008

Introduction

The "WDNR Whole Effluent Toxicity (WET) Program Guidance Document" (WET Guidance Document) was created in 1996 to assist staff, permittees, and others when making decisions regarding WET testing. It is intended for use in conjunction with the State of Wisconsin Aquatic Life Toxicity Testing Methods Manual (Methods Manual (PDF, 545KB), which states required test protocols (according to s. NR 219.04, Wis. Adm. Code). Part I of the WET Guidance Document was written primarily for Department staff to use when making permit decisions, although others may find useful information there as well. Part II provides guidance and clarification of existing requirements for permittees and others, concerning issues of importance to the WET program.

The Guidance Document is meant to contain all guidance related to the WDNR's WET Program, and is regularly updated as program needs change. Maintenance of this document is the responsibility of the Biomonitoring Coordinator, and it is updated with input from the Biomonitoring Team, staff, and others usually about once yearly. As chapters are revised, they are signed and effective dates changed so that users can insure use of the most recent guidance by verifying the l atest revision date. Suggestions for additional guidance or corrections to existing chapters should be sent to Kari Fleming.

NOTICE: The WET Guidance Document is intended solely as guidance, and does not contain any mandatory requirements except where requirements found in statute or administrative rule are referenced. This guidance does not establish or affect legal rights or obligations, and is not finally determinative of any of the issues addressed. This guidance does not create any rights enforceable by any party in litigation with the State of Wisconsin or the Department of Natural Resources. Any regulatory decisions made by the Department of Natural Resources in any matter addressed by this guidance will be made by applying the governing statutes and administrative rules to the relevant facts.

Revision #8 - July 2008

The latest revisions to the WET Guidance Document were made on July 1, 2008. Revisions to each of the chapters reflect comments received since their last update. Each chapter is effective upon the date of signature and users should begin to use them in accordance with the effective date on the bottom of each page. Revised chapters can be found on the WET Guidance Document page and should replace previous versions of the same chapter, which should then be discarded as they are no longer appropriate for use in the WET program. The following is a summary of the most significant revisions made. Users are encouraged to read revised chapters thoroughly, in order to be aware of all changes from previous versions.


Chapter 1.1 – Sampling For WET Testing
  • Clarifies that Section 2.2.7 of the Methods Manual requires that “Samples shall be chilled with ice or other means of refrigeration during and immediately after collection. Every effort should be made to achieve a sample temperature of < 4oC (without freezing).”
  • Sample equipment cleaning section updated and clarified (grab sampling equipment must be cleaned, too)
  • Artifactual toxicity may occur when sampling equipment is not cleaned regularly. Microorganisms can colonize surfaces that are in contact with the effluent. Some microbes can produce endotoxins that are toxic to the test organisms. Before sampling, we strongly recommend that you replace all tubing and clean any parts that contact effluent and receiving water samples.

    Chapter 1.3 - Representative Data, Reasonable Potential & WET Monitoring
    Updated references and information (removal of outdated information) for example:
  • p. 4 removed discussion of early 1990’s data which is no longer relevant.
  • p. 5 “Depending on the seasonal nature of the discharge and other factors, 3-4 passing tests conducted (at least 30 days apart) under normal operating conditions is enough to demonstrate that changes have resulted in toxicity removal.” Added to discussion of proving a TRE was successful.
    Other Changes:
  • Changes were made to WET methods in ~2004 to remove the “pathogen effect” from chronic fathead minnow tests. Since these changes were made, there have been no inconclusive tests due to this phenomenon.
  • “Full fish and aquatic life” replaced with “coldwater, warmwater sport fish, or warmwater forage fish” to more accurately reflect current classifications.
  • Addition of ethanol plants to list of industrial contributors. WET data collected from these facilities suggests there is a high potential for problems. Due to this potential, this category will receive 15 points in the WET Checklist process in order to insure that enough WET monitoring is being done to address these facilities.
  • Resolving GLI issues: The conflict between GLI regulations and DNR rules has existed for 8 years. Over time, staff have learned to collect more WET data in order to clarify toxicity situations and reduce backlogged permits. Language has been added to Chapter 1.3 to encourage staff to bring these situations to the attention of the Biomonitoring Coordinator as soon as possible, so that additional WET data can be collected, toxicity issues can be resolved, and backlogs can be avoided.

    Chapter 1.5 - WET Data Reporting, Review, & Interpretation
    Clarification was added in many areas, based on requirements in the WET Methods Manual:
  • WET Test Report Forms must include observations made by the permittee or lab that may influence test results or data interpretation…
  • The Biomonitoring Coordinator is primarily responsible for the review and interpretation of WET test results...
  • Section 5.3.3 of the Methods Manual requires dose-response relationships be reviewed to ensure that test endpoints are interpreted correctly...tests might need to be repeated within 30 days…Final decisions regarding the acceptability of tests based on review of dose-response information shall be made by the Biomonitoring Coordinator…
    Other clarification & edits:
  • Hormesis definition - It is not uncommon for the lowest concentration in a toxicity test to demonstrate an effect that is greater than the control. The apparent stimulation of growth/reproduction by low toxicant doses is well known in pharmacology and toxicology and is referred to as “hormesis”. Hormesis can happen when an organisms biological system “overreacts” to a toxicant present at low levels. This is a well known biological reaction and does not usually indicate an environmentally adverse effect.
  • Adjusted Figure 1.5.5 to remove effect in upper concentrations (less realistic, but better illustrates example of stimulation)

    Chapter 1.7 - Discharges with Water Quality Additives

    This chapter was rewritten to reflect new DNR guidance titled “Water Quality Review Procedures For Water Applied Biocides, Additives, Polymers, & Sediment Control Products” (Nov 2006)

    Chapter 1.8 – WET Enforcement Strategy

  • Updated reference to standard permit language that requires a TRE to be done after a retest failure (standard permit language changed in 2007)
  • Additional paragraph added to clarify existing policy: In general, the WDNR should not take serious enforcement action (e.g., referrals, fines) following violations of WET limitations, if staff agree that the discharger has adequately complied with its WPDES permit requirements for accelerated testing and conducting a TRE. More serious enforcement action would be appropriate if the permittee fails to aggressively conduct a TRE or is otherwise recalcitrant in addressing the toxicity. Exceptions to this general guideline include situations where the WET violations are of large magnitude or contributed to significant environmental impact; the permittee needs additional incentive to complete the corrective actions identified by a TRE; the permittee failed to eliminate/reduce toxicity within a reasonable time frame; or, the WET violation(s) were caused by circumstances within the control of the discharger and could have been reasonably avoided.

    Ch. 2.2 - Toxicity Reduction Evaluations
    Sections of this chapter were rewritten and expounded upon due to lessons learned from past TRE experiences:
  • Added a comprehensive list of TRE guidance documents available from other agencies (USEPA & SETAC)
  • Communication and cooperation between the permittee, their consultant, and the Department is essential in TRE plan development, review, and implementation...
  • Finding A Qualified TRE Consultant. Probably the most important beginning step in any TRE is the identification of a qualified consultant...
  • No Phase I TIE characterization test should be dropped from use on the basis that the toxicant it is designed to target are not likely to be present in the effluent. The investigator should approach effluent characterization without a preconceived notion as to the cause of toxicity...
  • Data Gathering. … Specific operating practices can be implemented by permittees that will greatly aid in identifying toxic effluent constituents. A thorough inventory of all contributions to the waste stream is a must...
  • Facility Housekeeping. It is important to verify that process chemicals are not overused, housekeeping practices are not contributing wastes directly to the effluent, and other facility practices are not contributing to toxicity...
  • Optimization Of Facility Operation. An attempt should be made to see what operational adjustments could be made that might reduce toxicity...

    Next Scheduled Revision

    In order to provide up-to-date guidance and program information, the Biomonitoring Coordinator reviews the Guidance Document regularly in order to determine if revisions are needed. Users are encouraged to continue to send comments to the Biomonitoring Coordinator, so comments can be considered during the next revision period. If you have questions regarding the WET Guidance Document, please contact Kari Fleming at: 608-267-7663, Kari.Fleming@wisconsin.gov, or DNR - WT/3, 101 S. Webster St., P.O. Box 7921, Madison, WI 53707-7921.

    Last Revised: Thursday July 03 2008
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