News and Publications

Calleguas Copper WER Developed by LWA is First Water-Effect Ratio Approved by Los Angeles RWQCB

As technical consultant to the Calleguas Creek Watershed Management Plan, LWA conducted a water quality study in Mugu Lagoon and Lower Calleguas Creek (in the Calleguas Creek Watershed, Ventura County) to determine a Water-Effect Ratio (WER) for copper using USEPA methods. The WER is used to adjust national copper criteria to local conditions to ensure protection of aquatic life. Based on the WER study results, LWA staff worked with RWQCB staff and stakeholders to adopt copper site-specific objectives into the Los Angeles Region Basin Plan in Fall 2006. The WER was the first ever approved in Los Angeles Region. The new copper objectives based on the WER were approved by the SWRCB in June 2007. A copy of the WER report can be viewed here.

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LWA Successfully Developed Four TMDLs in Southern California for Nutrients; Metals and Selenium; OC Pesticides and PCBs; and Toxicity

Since 2000, LWA has been the lead technical consultant for preparation of four TMDLs for the Calleguas Creek Watershed Management Plan (CCWMP). These stakeholder-led third party TMDLs are the only TMDLs in the State of California that have been developed by groups other than a regulatory agency. The pollutants covered by the four TMDLs are Nutrients; OC Pesticides and PCBs; Toxicity, Chlorpyrifos, and Diazinon; and Metals and Selenium. Our TMDL services included work plan preparation; water quality monitoring programs design and implementation; stakeholder outreach; preparation of the TMDL technical report; coordination with the RWQCB during TMDL development; and assistance to the client with the TMDL adoption process at the local, state, and federal levels. As of fall 2007, all four TMDLs have been fully adopted by state and federal regulatory agencies, and two of the TMDLs were approved by the state on the consent calendar. Information on the adopted TMDLs, including the LWA technical report on which each TMDL was based, may be viewed at the RWQCB website here.

LWA's work on the Calleguas Creek TMDLs was highlighted as a national Case Study in a recent Water Environment Federation (WEF) document, Third Party TMDL Development Tool Kit. Of the four case studies presented in the document, the Calleguas example is one of two successes. A copy of this document can be viewed here.

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Ammonia Site-Specific Water Quality Objective Developed by LWA Adopted by Los Angeles Regional Water Quality Control Board

LWA developed and implemented a work plan to develop a water effect ratio (WER) in support of an ammonia site-specific objective (SSO) for 3 major water bodies in Southern California: the Los Angeles River and tributaries, the San Gabriel River and tributaries, and the Santa Clara River. The LWA work effort included WER study design and approval by state and federal regulatory agencies; water quality sampling using USEPA protocols; and analysis of the water quality laboratory data to calculate site-specific objectives. The final SSO report was adopted by the Los Angeles Regional Board staff in June 2007—the first ammonia SSO adopted in California. A copy of the WER report can be viewed here.

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