California Code of Regulations
Title 23 - Waters
Division 4 - Regional Water Quality Control Boards
Chapter 1 - Water Quality Control Plans, Policies, and Guidelines
Article 9 - San Diego Region
Section 3989.2 - Total Maximum Daily Load for Dissolved Copper in Shelter Island Yacht Basin
Resolution No. R9-2005-0019, adopted on February 9, 2005 by the San Diego Regional Water Quality Control Board (San Diego Water Board), modified the regulatory provisions of the Water Quality Control Plan for the San Diego Basin by establishing a Total Maximum Daily Load (TMDL) for Dissolved Copper in Shelter Island Yacht Basin (SIYB), San Diego Bay.
The TMDL addresses toxicity in SIYB caused primarily by copper-based antifouling paints. The numeric targets were set equal to water quality criteria for dissolved copper as set forth by the U.S. Environmental Protection Agency in the California Toxics Rule to protect aquatic life from acute and chronic toxicity. The numeric target for dissolved copper is 3.1 micrograms/liter (µg/L) for continuous or chronic exposure (4-day average) and 4.8 µg/L (1-hour average) for maximum or acute exposures, not to be exceeded more than once every three years.
The TMDL was calculated to be 567 kilograms/year of dissolved copper, amounting to a 76 percent reduction in current loading from copper-based antifouling paints. Most of the load reduction will be required from passive leaching, as well as to a lesser extent from underwater hull cleaning of copper-based antifouling paints.
The dischargers responsible for meeting the copper reductions and allocations are the San Diego Unified Port District, marina owners and operators at SIYB, boat owners at SIYB, underwater hull cleaners at SIYB, and the City of San Diego.
In order to implement the TMDLs, the San Diego Water Board will (1) coordinate with governmental agencies having legal authority over the use of copper-based antifouling paints, which are registered pesticides; (2) regulate the discharge of copper to SIYB waters through the issuance of Waste Discharge Requirements (WDRs), Waivers of WDRs, and/or adoption of Waste Discharge Prohibitions; and (3) amend Order No. 2001-01, "Waste Discharge Requirements for Discharges of Urban Runoff from the Municipal Separate Storm Sewer Systems" to require that discharges of copper into SIYB waters not increase via the City of San Diego's municipal separate storm sewer system from existing loadings. Compliance with the allocations will be required over a 17-year staged compliance schedule. The first stage consists of an initial 2-year orientation period during which no copper load reductions are required. The subsequent 15 year reduction period is comprised of three stages during which incremental copper load reductions are required as shown below.
Table 1. Interim Loading Targets for Attainment of the TMDL
| Stage | Time Period | Percent Reduction from Current Estimated Loading | Reduction to be Attained by End of Year | Estimated Interim Target Loading (kg/year of dissolved Cu) |
| Stage 1 | Years 1-2 | 0% | N/A | N/A |
| Stage 2 | Years 2-7 | 10% | 7 | 1,900 |
| Stage 3 | Years 7-12 | 40% | 12 | 1,300 |
| Stage 4 | Years 12-17 | 76% | 17 | 567 |
1. New section summarizing amendments to Water Quality Control Plan for the San Diego Region filed 12-2-2005; amendments adopted by San Diego Regional Water Quality Control Board Resolution No. R9-2005-0019 2-9-2005; approved by OAL and operative 12-2-2005 pursuant to Government Code section 11353 (Register 2005, No. 48).
