On June 21, 2024, the Regional Water Quality Control Board, Central Coast Region (Central Coast Water Board) adopted Resolution R3-2024-0002, amending the Water Quality Control Plan for the Central Coastal Basin (Basin Plan) to incorporate total maximum daily loads (TMDLs) with an associated implementation strategy for reducing organophosphate pesticide loading to surface waters in the lower Salinas River watershed, Monterey County, California for the following:

- three organophosphate pesticides (chlorpyrifos, diazinon, and malathion);

- additive toxicity of those pesticides; and

- individual toxicity.

The State Water Resources Control Board approved the Basin Plan amendment in Resolution 2025-0031 on October 7, 2025.

TMDLs are a requirement of the federal Clean Water Act when a waterbody is identified as not attaining applicable water quality standards. Responsibility for achieving organophosphate pesticide load reductions falls upon several point source and nonpoint source implementing parties as described in Attachment A to Resolution R3-2024-0002. The Central Coast Water Board will rely on existing regulatory mechanisms, voluntary actions, and grant funding to ensure implementation actions to reduce organophosphate loading to the watershed are carried out and maintained by implementing parties.

TMDL attainment dates are established for achieving water quality objectives. The Central Coast Water Board will track progress towards achieving the TMDLs in accordance with California Water Code section 13242. If existing efforts are not expected to achieve the TMDLs as scheduled, the Executive Officer or the Central Coast Water Board may require changes to existing monitoring, reporting, and/or implementation efforts pursuant to California Water Code sections 13263, 13267, and/or 13383.

History

1. New section summarizing amendment to basin plan filed 2-25-2026; amendment approved by State Water Resources Control Board Resolution No. 2025-0031 on 10-7-2025; amendment approved by OAL pursuant to Government Code section 11353 on 2-25-2026 (Register 2026, No. 9).