Phase 2 sampling underway for study examining how to update copper concentration limits for streams

SCCWRP and its partners have begun collecting water quality data from three additional watersheds in the Los Angeles region as part of an ongoing effort to evaluate the feasibility of using a toxicity analysis method known as the Biotic Ligand Model (BLM) to develop copper site-specific objectives for freshwater streams.

The expanded Phase 2 sampling effort, launched in February, will complement data collected from two watersheds during an initial sampling phase last year. The goal of both sampling efforts is to fill in data gaps that researchers identified after inventorying historical water quality data from streams.

Collecting the data is a necessary precursor for researchers to generate BLM results for Los Angeles-area streams. The BLM estimates how chemical characteristics of a water body influence the bioavailability and, ultimately, the toxicity of metal contaminants such as copper.

The Los Angeles Regional Water Quality Control Board is interested in potentially using the BLM to update site-specific water quality objectives for streams across the Los Angeles region. The BLM is an alternative to the established Water Effects Ratio toxicity analysis method.