MJ Paul Tetra Tech Inc. Center for Ecological Sciences RTP, NC USING BIOLOGICAL RESPONSES IN NUTRIENT CRITERIA DEVELOPMENT: APPLICATIONS, OPPORTUNITIES, AND CONCERNS

 We can simplify the linkages  This has Clean Water Act implications NUTRIENT POLLUTION IMPACTS BIOLOGY

40 CFR § Criteria  States must adopt water quality criteria that protect designated uses, based on science and composed of sufficient parameters;  These should be:  Numeric or;  Narrative “where numerical criteria cannot be established or to supplement numerical criteria”  Focus has been on deriving numeric nutrient criteria  How is this done?  4 major approaches – often in a weight of evidence approach NUTRIENT CRITERIA DEVELOPMENT

 Reference based – biology can be used here NUMERIC NUTRIENT CRITERIA DEVELOPMENT 25 th 75 th 90 th

 Stressor-response based – biology most definitely used here NUMERIC NUTRIENT CRITERIA DEVELOPMENT Ln(TP) IBI Score

 Mechanistic Models  E.g., WASP, QUAL-2k, EFDC, CE-QUAL, HSPF, MIKE…  Model specific endpoints to generate nutrient goals NUMERIC NUTRIENT CRITERIA DEVELOPMENT

 Scientific Literature NUMERIC NUTRIENT CRITERIA DEVELOPMENT

 Outcome – numeric value  One or more lines of evidence NUMERIC NUTRIENT CRITERIA

 Typically criteria are implemented as they are written:  E.g., 40 ug/L annual average not to be exceeded more than 1 in 3 years  With nutrients, some states have proposed linked biological and nutrient criteria:  Or as a multimetric: Composite Criteria = P chla + P DO + B + N IMPLEMENTING NUMERIC NUTRIENT CRITERIA Biology ok Biology not ok Nutrients okNutrients not ok Not Impaired Further Study Impaired Need Cause Nutrient Impaired

 Why?  Lack of cause-effect  Variability of response of algae/invertebrates/water chemistry to nutrient enrichment  Cannot reliably predict a value that will produce aquatic life use impact  False positives would be costly LINKED BIOLOGICAL AND NUTRIENT CRITERIA ABC D X X X Ln(TP) IBI Score

 If nutrient concentrations cannot predict biological response, then how can a biological response be used to infer nutrients are too high? If they can, why do you need confirmation? Does not improve with a “building the case” approach  If cannot reliably link nutrients to algae, DO and/or IBI, then how can they be combined to infer a numeric nutrient impairment? LINKED BIOLOGICAL AND NUTRIENT CRITERIA ISSUES AB X A B X C D X X

 If models are inaccurate, immediately concluding that biological impacts are due to nutrients is questionable stressor identification LINKED BIOLOGICAL AND NUTRIENT CRITERIA ISSUES

 What would such an approach open up for other criteria (e.g., priority pollutants)?  E.g., Cd limits derived to protect 5 th percentile of sensitive lab species  Combine with proof of in-stream aquatic life impact? LINKED BIOLOGICAL AND NUTRIENT CRITERIA ISSUES

 Waiting for evidence of impacts on aquatic life use before acting on nutrient pollution may conflict with (a) - States must adopt water quality criteria that protect designated uses;  It is also ecologically risky… LINKED BIOLOGICAL AND NUTRIENT CRITERIA ISSUES “Expectations that ecosystems will return to original conditions …following reduced nutrient inputs may be fundamentally flawed….”

 Reduce the variability – a big part of our problem may be classification…  Accept and apply risk based reasoning  Derive numbers based on reducing the risk of impacts, not on being 100% correct;  Existing water quality criteria are very precautionary SOLUTIONS Classification Ecology

 Incorporate the variability into the criteria setting step, not the assessment step  If response conditions are fine and nutrients elevated (within an acceptable range), then refine numeric nutrient criterion site- specifically  Such an approach protects existing biological condition from nutrients rather than requiring proof of impact before action SOLUTIONS

 Incorporate measures with safety levels – range concept  Reference based values = lower trigger  Stressor-response based values (invertebrate/fish) = upper values  But, use biological measures EARLY in the causal pathway SOLUTIONS Listed for Nutrients Not Listed Listed for Nutrients Not Listed SSC Listed for Nutrients Nutrient Threshold Exceeded Biological Threshold Exceeded NoYes LowHigh Yes No

 Incorporate early warning measures for bio-confirmation SOLUTIONS

 Require proof on multiple biological endpoints  If nutrients elevated, but chlorophyll is not; then you need to confirm that all aspects of aquatic life are okay.  Nutrients can affect many aspects of aquatic life in streams (even shaded headwaters):  Algae  Invertebrates  Fish  Bacteria  Fungi  Function SOLUTIONS

 This discussion is all VERY good for biology  Whichever way it goes  Bio-confirmation or No (Focus on ALU)  Support technical research  Fund more experimental work  Field and lab dosing experiments  Develop and apply statistical approaches for reducing variability  Develop new and refine existing biological response tools  Ask experts what they think SOLUTIONS

THANKS Huffy The Bug Slayer