1. Whole Effluent Toxicity (WET)

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

3. Method Manuals

4. The Standards

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

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

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

8. 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%

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

10. 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

11. 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.

12. 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
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