Expert panel evaluates SCCWRP nutrient science plan

Posted August 7, 2015
Multiple varieties of algal matter cover the rocky floor of the Santa Margarita River watershed near Temecula. The science plan that SCCWRP and its partners have written to support development of statewide nutrient objectives is intended to limit nutrient inputs that are triggering eutrophication in wadeable streams statewide.

A four-member expert review panel tasked with reviewing a science plan supporting the State Water Board’s effort to develop nutrient objectives for California wadeable streams has concluded that SCCWRP’s approach is “thorough and state-of-the-art,” with appropriate opportunities to engage stakeholders throughout the process.

The review process culminated with a two-day panel meeting at SCCWRP in June, and marks an important milestone for this multi-year project, which is expected to conclude in 2017. SCCWRP leads a team of scientists from Tetra Tech Inc. and the U.S. Environmental Protection Agency’s Office of Research and Development that has produced the “Science Plan to Support the Development of a Nutrient Control Program for California Wadeable Streams.”

In particular, the review panel applauded SCCWRP’s plan to use a consensus approach among experts to establish eutrophication indicator ranges that correspond to particular levels of ecological condition, a concept known as the Biological Condition Gradient (BCG) Model. Tetra Tech and SCCWRP will begin development of the model this fall, allowing experts to use indicator data from stream algae and/or benthic macroinvertebrates to place stream sites into classes based on their condition.

The BCG model is intended to improve policymakers’ understanding of what nutrient targets are realistically attainable for a variety of common stream types across California.

The expert panel also issued a series of recommendations to SCCWRP designed to improve transparency during the development of nutrient objectives for streams. The panel recommended, among other things, that stakeholders be furnished with tools that can more explicitly link nutrient source information to the concentrations of nutrients observed in a stream. The panel also recommended that more specific information be provided regarding how uncertainty will be quantified in statistical models that predict the effects of nutrients on biological responses.
To request a copy of the expert review panel’s full report, or for more information about this project, contact Dr. Martha Sutula.


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