Sacramento-San Joaquin Delta
Methylmercury TMDL
The Regional Board adopted the Delta Methylmercury Total Maximum Daily Load (TMDL) on April 22, 2010. The State Water Resources Control Board and the California Office of Administrative Law subsequently approved it, and the U.S. EPA granted final approval on October 20, 2011, marking the beginning of Phase 1. Adopted as a Basin Plan Amendment, the TMDL includes an implementation program to reduce methylmercury and inorganic mercury in the Delta. Together, the TMDL and its implementation program form the Delta Mercury Control Program (DMCP). The DMCP required a program review incorporating updated scientific findings and control measures. The Phase 1 Review and Phase 2 began in October 2022, and Board staff are currently conducting the Phase 1 Review.
What's New!
- Delta Mercury Control Program Staff Workshop (03 September 2026)
Staff Report for Scientific Peer Review
- Staff Report for Scientific Peer Review
- Cover Letter from Executive Officer on the DMCP Phase 1 Review of the Sacramento – San Joaquin Delta Estuary TMDL for Methylmercury Staff Report for Scientific Peer Review
- DMCP Phase 1 Review of the Sacramento – San Joaquin Delta Estuary TMDL for Methylmercury Staff Report for Scientific Peer Review (March 2024)
- R Scripts & Analysis (.zip)
- Independent External Scientific Peer Review
Per the requirements of California Health and Safety Code section 57004, Board staff requested external scientific peer review of the scientific basis of proposed revisions to the Delta Mercury Control Program outlined in the Staff Report for Scientific Peer Review. Reviewer’s CVs are available upon request.
Public Meetings and Workshops
- Staff Workshop (03 September 2026)
- Public Notice of Staff Workshop
- Staff Workshop Agenda
- Staff Workshop Presentation Recording
- Staff Workshop Presentation Slides
- Staff Workshop (12 September 2024)
- Delta Mercury Control Program Review Discharger Meeting (4 December 2023)
- Delta Mercury Control Program and Total Maximum Daily Load Review, CEQA Scoping Meeting and Public Workshop Notice (24 February 2021)
- Delta Methylmercury Public Workshop for Control Study Entities (10 September 2020)
Final Reports and Approvals
- DMCP Phase 1 Review of the Sacramento – San Joaquin Delta Estuary TMDL for Methylmercury Staff Report for Scientific Peer Review (March 2024)
- Final Basin Plan Amendment (October 2011, pages 9-44)
- Basin Plan Amendment Staff Report (April 2010)
- TMDL Staff Report (April 2010)
- Delta Mercury Exposure Reduction Program (MERP) Meetings and Program Documents
Phase I Methylmercury Characterization and Control Studies
The first phase of the Delta Mercury Control Program required discharging entities to develop characterization and control studies to evaluate approaches for managing methylmercury.
- Phase 1 Methylmercury Characterization and Control Study Final Reports are listed on the Archived Documents webpage.
The Central Valley Water Board requested the Delta Science Program coordinate and conduct an independent review of these studies to assess the scientific validity of methods, analyses, and conclusions.
- The Final Independent Scientific Reports are available below:
- Independent Scientific Review Panel's review of Municipal Wastewater and Urban Stormwater control studies (Part 1).
- Independent Scientific Review Panel's review of Tidal Wetlands and Open Water Habitat Final Reports (Part 2).
- The Independent Scientific Review Panel's Charge, Tidal Wetlands and Open Water Habitat Final Reports, and other associated documents are available on the Delta Stewardship Council's Delta Science Program's Independent Scientific Review of the Delta Mercury Control Program Phase 1 webpage.
Email Subscription List
Subscribe to the TMDL - Delta Mercury email list to receive notifications and updates.
Contact Us
- Program Contact
Lauren Leles
(916) 464-4668
Lauren.Leles@waterboards.ca.gov - Web page problems: Webmaster5@waterboards.ca.gov
- Report an Environmental Concern
