SAB Says EPA Nutrient Criteria Guidance Is Inadequate, Not Defensible

By Inside EPA

The criticisms come as EPA is moving forward in Florida to develop numeric nutrient criteria in response to an activist lawsuit and as environmentalists are pushing the agency to craft numeric criteria elsewhere, arguing that risk-based, quantitative numeric criteria are more easily enforceable than the narrative criteria most states use for nutrients.

Under the Clean Water Act, states and other regulators use water quality criteria to set enforceable water quality standards that are used to set discharge permit limits. Nutrients, which stem from fertilizer runoff, power plant emissions and discharges from point sources, are responsible for eutrophication — a process that results in reduced oxygen levels in waters, such as the hypoxic “dead zone” in the Gulf of Mexico and other large watersheds.

But in a draft report released for comment Nov. 19, SAB pans the agency’s nutrient guidance, saying it only “provides a primer on a limited set of statistical methods that could be used in deriving nutrient criteria based on stressor-response relationships” and “in its present form, . . . does not present a complete or balanced view of using the statistical methods to develop criteria.” 

The SAB review stems from concerns about the approach three Pennsylvania communities raised last year where Region III was using it to develop stringent phosphorus stream standards. In an Aug. 21, 2008, request for a peer review, the communities say the approach would “result in billions of dollars in additional

[wastewater] treatment costs in Pennsylvania.” 

A source involved in the peer-review request says, “The approach only gives you a probability,”  and is consequently inappropriate for nationwide use “deriving protective stream nutrient standards.”

“From the stream standard that [Region III] set, there was a 50 percent chance you might meet the stream standards they want,” the source says. “You can’t do that from a scientifically defensible approach. . . . Nutrients aren’t toxics.” 

SAB panel members signaled at a Sept. 11 meeting that while they believed the plan to be viable, and that setting numeric nutrient criteria is important, the document in its current form is not adequate.

Specifically, SAB says the method used to determine nutrient criteria in the guidance is not adequate as a “stand-alone” method “because statistical associations do not prove cause-and-effect.” Instead, the approach should be used in concert “with other available methodologies in the context of a tiered approach where uncertainties in different approaches are recognized, and weight of evidence is used to establish the likelihood of causal relationships between nutrients and their effects for criteria derivation.”

The methods also need to take into account downstream effects of nutrients, and a more specific framework for creating nutrient criteria.

The panel also asks EPA to better explain how it is using the guidance in “decision-making and regulatory processes and, specifically, how it relates to and complements EPA’s other nutrient criteria approaches, technical guidance manuals, and documents.”  

The SAB is taking stakeholder and public comments prior to and following a Dec. 3 conference call to discuss the draft report.


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