Q. If I want to switch chemicals in my water treatment process, can I complete an antidegradation analysis myself and all in one application?
A. Yes. You can do the antidegradation analysis yourself, so long as all methods of sample collection, preservation, and analysis are conducted using approved methods and tested by a certified laboratory. (See 40 CFR 136).
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States requires permittees to complete an antidegradation analysis when proposed new or expanded activities will degrade water quality (See 40 CFR 131.12). In limited circumstances, such as conducting tests or trials of new chemicals, states may allow you to use a temporary or limited determination initially and followed with a complete antidegradation analysis for the selected chemical(s) that will be used permanently.
You will need to check with your respective state to determine what information is required to be submitted, which may include:
- Length of time during which the water quality will be lowered
- Percent change in ambient conditions
- Pollutants affected
- Likelihood for long-term water quality benefits to the water body
- Degree to which achieving the applicable water quality standards during the proposed activity may be at risk
- Potential for any residual long-term effects on existing uses
As to your second question, a single antidegradation analysis can cover multiple chemicals or pollutants of concern.
For more information on antidegradation, you can refer to EPA’s page on antidegradation.