§ 3939.23. Total Maximum Daily Load for Metals and Selenium in Calleguas Creek, Its Tributaries, and Mugu Lagoon.

Los Angeles Regional Water Quality Control Board (Los Angeles Water Board) Resolution No. R4-2006-012, adopted on June 8, 2006 by the Los Angeles Water Board, modified the regulatory provisions of the Water Quality Control Plan for the Los Angeles Region (Basin Plan) by (1) revising the Table of Contents, (2) adding introductory text for Chapter 7 (Total Maximum Daily Loads), and (3) establishing a Total Maximum Daily Load (TMDL) for metals and selenium in Calleguas Creek, its tributaries, and Mugu Lagoon. The State Water Resources Control Board approved the amendment on October 25, 2006 under Resolution No. 2006-0078.

Three of 14 reaches in the Calleguas Creek Watershed, including Revolon Slough, Lower Calleguas Creek - Reach 2, and Mugu Lagoon have been listed under the federal Clean Water Act section 303(d) as not meeting standards due to elevated concentrations of metals and selenium in water. Technical studies indicate Mugu Lagoon is a sink for metals, which endanger aquatic organisms and impair the existing habitat. Aquatic organisms also accumulate metals, which cause human health concerns. The beneficial uses most affected by metals and selenium loadings into Calleguas Creek, its tributaries, and Mugu Lagoon include habitats which support wildlife and rare, threatened, or endangered species, as well as habitats which support estuarine and wetland ecosystems. The amendment establishes four types of numeric targets with which load allocations and waste load allocations were calculated. The types of numeric targets are water quality targets for copper, nickel, zinc, mercury, and selenium; fish tissue targets for mercury; bird egg targets for mercury and selenium; and sediment quality guidelines for copper, nickel, and zinc for 303(d)-listed reaches. In addition, the Basin Plan amendment specifies final waste load allocations for point source discharges and load allocations for nonpoint source discharges of metals and selenium. The TMDL establishes a ten year implementation schedule for publicly owned treatment works and other National Pollutant Discharge Elimination System Permittees, and a 15 year implementation schedule for agricultural and permitted storm water dischargers to reduce the loading of metals and selenium to Calleguas Creek. The TMDL also authorizes the use of best management practices, to the extent authorized by law, for various dischargers including agricultural and storm water dischargers. The implementation plan includes a combination of water quality monitoring, hot-spot waste removal, waste collection, and sediment control. The TMDL also consists of a monitoring program to assess compliance with waste load allocations. The monitoring program also stipulates the collection of additional data to evaluate the uncertainties and assumptions made in development of the TMDL and to consider potential management scenarios.

The Basin Plan amendment includes a brief description of the Calleguas Creek Watershed and the existing conditions contributing to water quality problems. Calleguas Creek metals and selenium TMDL numeric targets, source analysis, linkage analysis, waste load allocation, load allocation, margin of safety, future growth, critical conditions, implementation plan, and compliance schedule are also discussed in the Basin Plan amendment.

HISTORY

1. New section summarizing amendments to basin plan filed 2-6-2007; amendment approved by State Water Resources Control Board Resolution No. 2006-0078 on 10-25-2006; amendments approved by OAL pursuant to Government Code section 11353 on 2-6-2007 (Register 2007, No. 6).