Calleguas Municipal Water District

LWA provides technical water quality support to the Calleguas Creek Watershed Management Plan (CCWMP), assisting in watershed planning, monitoring, and management activities. Since 1998, our work has included:

  • Stakeholder facilitation
  • TMDL development and implementation
  • Monitoring current loads, pollutant sources, and evaluate progress in attaining TMDLs
  • Preparation of regulatory agency reports
  • Review of water quality standards, regulations, plus development and implementation of studies to support Basin Plan changes
  • Development of analysis and management tools for water quality models and databases
  • Support of MS4 permit negotiations

In 1998 LWA developed and implemented the Calleguas Creek Characterization Study (CCCS) to assess surface water, discharge, and groundwater conditions and to identify constituents of concern and pollutant sources in the watershed. Additional Work Plans were developed to complete TMDLs for salts, metals, bacteria, toxicity, pesticides and PCBs.

LWA facilitated meetings with stakeholders and were responsible for working with the broad stakeholder group, the Regional Board, and USEPA to develop scientifically defensible and reasonable TMDLs. TMDL reports developed by LWA for the CCWMP have to-date formed the basis for five TMDLs adopted by the State and USEPA (Nutrients, Toxicity TMDL, Organochlorine Pesticides and PCBs, Metals, and TDS, Sulfate, and Boron TMDL, which included a specific implementation plan for Chloride). Additionally, as part of the TMDL development process LWA worked with stakeholders to develop and implement several special studies including a Water-Effect Ratio (WER) for copper, a watershed-scale microbial source tracking study, a nutrient loading and algae impairment study, and a dry season urban runoff characterization study. The results of the WER study were adopted into the Los Angeles Region Basin Plan in 2006.

As a component of the Bacteria TMDL and in conjunction with researchers from the University of California at Davis, the microbial source tracking study was conducted. The goal of this study was to provide information regarding which land uses (urban, agricultural, etc.) and source types (human vs. non-human) are responsible for beneficial use impairments.

Following the completion of the TMDL development efforts, LWA initiated the development of the Calleguas Creek Watershed TMDL Compliance Monitoring Program (CCWTMP) covering all TMDL monitoring requirements for all responsible parties participating in the CCWMP. The effort to complete this coordinated monitoring program included site selection, completion of a Regional Water Quality Control Board approved Quality Assurance Project Plan (QAPP) covering all TMDL monitoring requirements, coordinating with existing waste water treatment plant monitoring efforts, management of the collection of water, tissue, and sediment sampling efforts, compilation and management of new and historic data, and completing all required annual report.