Whole Effluent Toxicity (WET)

WET and the IPs WET implementation must conform to: The method manuals The Standards EPA Region VI

Method Manuals

The Standards

EPA Region VI Approves Standards and IPs 2005 WET Policy December 28, 2015 letter 1998 Memorandum of Agreement

IPs Within those constraints, we are free to propose policy and procedures. Several examples will be presented.

Acceptability Criteria Hypothesis Testing (NOEC) CV PMSD Point Estimate (IC25)

Menu 2 Intermittent stream (Menu 1) within 3 miles of perennial waters (Menu 3) Normally requires chronic testing to protect the aquatic life of the perennial waters… Except when the discharge flow is <10% of the 7Q2 of the RW, then requires 48-hour acute testing at 100%

Type of Test Freshwater vs. Saltwater Testing 1 ppt vs 2 ppt Reproduction in the water flea, Ceriodaphnia dubia

WET Determination Federal law requires WET testing for all EPA-designated majors The IPs allow us to also require some industrial minors to perform WET testing 24-hour acute also used at discretion

IPs and Stakeholders We value the input of our Stakeholders. Now is the time to start thinking about any changes you would like to see and propose them when the draft IPs are issued.

SUMMARY The IPs are guidance, not rule, which we mostly adhere to. However, being guidance, they can be flexible and can change over time, especially with stakeholders input. Michael Pfeil (512) 239-4592