LWA News

LWA Successfully Developed TMDLs in Southern California for Nutrients; Metals and Selenium; OC Pesticides and PCBs; and Toxicity
September 2007

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 (pdf).

Calleguas Creek Watershed Metals and Selenium TMDL 3/06

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Calleguas Creek Nutrient TMDLs
March 2006

Beginning in 2002, LWA has written the technical reports for four TMDLs for the Calleguas Creek Watershed Management Plan, Ventura County, California. The TMDLs completed for local surface waters to date are for Nutrients; OC Pesticides and PCBs; Toxicity, Chlorpyrifos, and Diazinon; and Metals and Selenium. The TMDLs were developed in close cooperation with the state and watershed stakeholders. The stakeholders accepted and endorsed the proposed TMDLs. The State of California acknowledged the TMDLs to be technically and legally sound by adopting them into the Los Angeles Region Basin Plan. The TMDLs were subsequently approved by the United States Environmental Protection Agency (USEPA) for inclusion in the state water quality standards.
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Calleguas Creek Watershed OC Pesticides and PCBs TMDL Technical Report 6/05

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Calleguas Creek Watershed Toxicity, Chlorpyrifos and Diazinon TMDL 4/05

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Strategic Plan for the Reduction of Mercury-Related Risk in the Sacramento River Watershed 2002

LWA completed a strategic plan for 2002 for managing mercury in the Sacramento River watershed. Mercury sources and pathways were characterized in this detailed plan, and with broad stakeholder input, a plan of action was developed to address uncertainty and controllable sources. Five years later, this report continues to provide a framework for action on mercury pollution through focused research and remediation projects.

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Clean Estuary Partnership: North of Dumbarton Bridge Copper and Nickel Site-Specific Objective (SSO) Derivation 3/05

LWA, in cooperation with Eisenberg, Olivieri and Associates (EOA), prepared a Work Plan in 1998 to develop site-specific objectives (SSOs) for copper and nickel in San Francisco Bay and began collecting data to support this effort in 2000. This report describes the methodologies and rationale for the establishment of site-specific water quality objectives for copper and nickel in San Francisco Bay North of the Dumbarton Bridge (NDB). Methodologies used conform with USEPA guidance for development of site-specific objectives and are consistent with approaches used in the development and approval of site-specific objectives for copper and nickel in the Lower South Bay. This is one of five reports used to support the adoption of SSOs for copper in the San Francisco Bay.

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Clean Estuary Partnership: North of Dumbarton Bridge Copper and Nickel Conceptual Model and Impairment Assessment Report 3/05

LWA, in cooperation with Eisenberg, Olivieri and Associates (EOA), prepared a Work Plan in 1998 to develop site-specific objectives (SSOs) for copper and nickel in San Francisco Bay and began collecting data to support this effort in 2000. This report includes an impairment assessment and a conceptual model for copper and nickel in the San Francisco Bay. The impairment assessment summarizes existing data on copper and nickel in water, sediment, and biota and compares them to environmental standards. The assessment also documents ongoing and proposed source control measures for copper and nickel. The conceptual model describes the sources of copper and nickel to the Bay and the processes that determine concentrations and fate of these materials to the ecosystem. It uses available information to predict how the ecosystem would respond to management actions that reduce ongoing inputs of copper and nickel. This is one of five reports used to support the adoption of SSOs for copper in the San Francisco Bay.

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Validation and Update of a Model Used to Predict Copper Toxicity to the Marine Bivalve Mytilus sp. 8/05

LWA worked in conjunction with the Copper Development Association to collect data necessary to calibrate a model that may be used to predict the toxicity of copper to the marine bivalve Mytilus sp. This model serves as a saltwater alternative to the Biotic Ligand Model, which has only been approved for modeling metal toxicity in freshwater environments. LWA collected copper toxicity data and dissolved organic carbon (DOC) data in Calleguas Creek Watershed to supplement the model developers’ existing database.

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