Skip to main content


Buy Article:

$9.50 plus tax (Refund Policy)

Or sign up for a free trial

Located in Ventura County California, the Calleguas Creek Watershed (CCW), though relatively small in area, suffers from more water quality impairments than most California watersheds, as defined by the USEPA's 303(d) list. Local stakeholders, along with the Los Angeles Regional Water Quality Control Board (LARWQCB), began a watershed planning process over eight years ago to develop a better understanding of the watershed and a strategy to address impairments.

The local stakeholders developed a comprehensive series of work plans designed to develop TMDLs to address groups of constituents in the 343 square mile watershed. TMDLs have been completed for three groups of constituents: (1) metals, (2) legacy pesticides, and (3) chlorpyrifos, diazinon and toxicity of unknown causes in water and sediment. The process followed in California appears to be unique in several respects. The purpose of the presentation is to present these unique aspects, with their advantages and disadvantages as experienced with CCW TMDL development, and to relate that experience to urban areas in general.

The general pollutant sources in the CCW watershed are agricultural, open space, community wastewater point discharges, and urban runoff. There are four incorporated communities within the watershed: Thousand Oaks, Simi Valley, Camarillo, and Moorpark. The total population in the watershed is approximately 334,000.

The first significant uniqueness was that the TMDLs were not prepared by a state or federal agency, as is common across the Nation. Rather the stakeholders themselves directed and provided the primary sources of funding for TMDL development. This approach provides many advantages, the first being an increase in funding to support the process. The Stakeholder groups included the cities, wastewater treatment facilities, agriculture interests, and environmental groups. Stakeholders chose to take direct responsibility because of the potential implications of TMDLs, and believed that substantial funding was necessary for a thorough technical analysis. Stakeholder involvement and participation was directly responsible for the development of the allocations and implementation plan. The authors will explain the process of stakeholder involvement, and the iterative interaction process with State agency and USEPA staff.

A second uniqueness relates to the Implementation Plan. Typically elsewhere the Implementation Plan identifies NPDES permit requirements including a mix of BMPs to be carried out to achieve the allocated loadings. This may not always be appropriate given the complexity of the beneficial use/water quality impairment and the lack of knowledge of the source(s) and spatial and temporal variation of the pollutant(s) causing the impairment. We therefore design the implementation plan as a stepwise process to carryout additional studies believed necessary to properly identify the effectiveness and costs of particular BMPs or strategies before prescribing BMPs.
No Reference information available - sign in for access.
No Citation information available - sign in for access.
No Supplementary Data.
No Article Media
No Metrics

Document Type: Research Article

Publication date: 2007-01-01

More about this publication?
  • Proceedings of the Water Environment Federation is an archive of papers published in the proceedings of the annual Water Environment Federation® Technical Exhibition and Conference (WEFTEC® ) and specialty conferences held since the year 2000. These proceedings are not peer reviewed.

    A subscription to the Proceedings of the Water Environment Federation includes access to most papers presented at the annual WEF Technical Exhibition and Conference (WEFTEC) and other conferences held since 2000. Subscription access begins 12 months after the event and is valid for 12 months from month of purchase. A subscription to the Proceedings of the Water Environment Federation is included in Water Environment Federation (WEF) membership.

    WEF Members: Sign in (right panel) with your IngentaConnect user name and password to receive complimentary access. Access begins 12 months after the conference or event
  • Subscribe to this Title
  • Membership Information
  • About WEF Proceedings
  • WEFTEC Conference Information
  • Learn about the many other WEF member benefits and join today
  • Ingenta Connect is not responsible for the content or availability of external websites
  • Access Key
  • Free content
  • Partial Free content
  • New content
  • Open access content
  • Partial Open access content
  • Subscribed content
  • Partial Subscribed content
  • Free trial content
Cookie Policy
Cookie Policy
Ingenta Connect website makes use of cookies so as to keep track of data that you have filled in. I am Happy with this Find out more