Welcome to the Calleguas Creek Watershed

Metals Work Plan

Various reaches within the Watershed are listed on the California 2002 Clean Water Act (CWA) Section 303(d) list of water quality limited segments as impaired due to metals. The goal of the Metals Work Plan is to identify the tasks required to address the beneficial use impairments caused by metals.

The strategy outlined in this work plan is three fold. Recent data have indicated that current concentrations of many metals in the Watershed do not exceed water quality objectives. Monitoring will be conducted to determine whether or not metals impairments still exist in the watershed in light of this new data. Secondly, site-specific objectives will be developed for copper and nickel. Finally, if necessary, TMDLs will be developed for metals not meeting the current or site-specific water quality objectives.

Responsible Agencies

The complete accounting of the responsible agencies and parties to carryout the Metals Work Plan has not yet been formalized, however the Habitat and Recreation Subcommittee is taking responsibility for providing policy guidance to the technical consultant. An MOU similar to the Salts Work Plan MOU will eventually be developed to formalize the funding of the Metals Work Plan.

Metals Monitoring

Quarterly monitoring conducted in 1997 and 1998 indicated that, for most metals, current concentrations do not exceed objectives in the California Toxics Rule (CTR). However, the number of samples collected was not sufficient to justify delisting the metals. One of the first priorities of the work plan is to conduct a monitoring program to verify that metals are currently impairing the CCW and collect a sufficient number of samples to justify delisting the metals should the current concentrations meet water quality objectives.

Site-Specific Objective Development

Current water quality monitoring indicates that copper, and potentially nickel, in the lower Calleguas Creek and Mugu Lagoon, are exceeding water quality objectives. The California Toxics Rule (CTR) objectives for copper, nickel, and several other metals are expressed as the dissolved concentrations of a metal in the water multiplied by a water effects ratio (WER). Multiplying by a WER, developed in accordance with EPA guidelines, accounts for the actual toxicity of a metal in specific site waters. As copper listings are based on exceedances of the CTR numeric concentrations without consideration of water body-specific conditions, a WER study will be performed to develop Site Specific Objectives (SSOs) for Mugu Lagoon and Lower Calleguas Creek. It is anticipated that SSOs, developed in accordance with EPA guidance and approved by the LARWQCB and EPA, will demonstrate that the beneficial uses are not impaired by existing copper concentrations. Dissolved concentrations of copper will be measured during the monitoring phase of this work plan to ensure that current water quality meets the appropriate criterion, including a SSO developed and approved through this work plan. If, after the completion of a SSO and monitoring, the current copper concentrations do not exceed the water quality objective the results can be used by the LARWQCB to consider delisting copper in the applicable reaches.

Additionally, consideration will be given to the recalculation of the national nickel saltwater criteria, which was performed in conjunction with EPA-approved studies conducted in South San Francisco Bay. Those studies support an adjustment of the CTR nickel criteria and provide scientific support for developing an alternative SSO for nickel in Mugu Lagoon. It is likely that the EPA will be adopting this new national criteria for nickel, which makes its applicability to Mugu Lagoon even more appropriate.

Once these evaluations are complete, recommended basin plan amendments will be submitted to the LARWQCB.

TMDL Development

All of the monitoring and work to develop SSOs can be used in the development of TMDLs if determined to be necessary. The decision to complete the development of TMDLs for the various metals listed on the proposed 303(d) list will depend on the findings and approval of the SSOs developed as part of this work plan. If monitoring data demonstrates that waters are no longer considered impaired, TMDLs may not be necessary. However, should the monitoring demonstrate that impairments still exist, then TMDLs will be developed for those metals.

Timing

The timing of the completion of the various tasks outlined in this work plan is contained in the work plan time schedule summary. The Metals TMDL Work Plan is to be completed by June 2006 to meet the Consent Decree deadline of March 22, 2007.

Metals Work Plan

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