California's State Water Resources Control Board is teeing up a major rewrite of dairy wastewater rules for the Central Valley, proposing a framework that would eventually force dairies to match manure and fertilizer applications with groundwater protections for nitrate.
In a revised draft order released Monday, staff recommend remanding the Central Valley Water Quality Control Board’s 2013 dairy general waste discharge requirements and directing the regional board to develop interim and final permits for nitrogen discharges. The proposal would apply beyond the dairies formally covered under the 2013 order, reaching all Central Valley dairies subject to regional board authority, including new, expanded or consolidated operations.
State board staff found that dairy manure management is a significant contributor to Central Valley nitrate contamination and that land application, not just lagoon seepage, is the dominant pathway. The order says the average manure nitrogen application on dairy cropland adds up to 890 pounds per acre, far above CDFA crop guidelines cited for silage corn and wheat.
The proposed benchmark is a nitrogen discharge limit, requiring nitrogen from any aspect of a dairy’s operations to stop causing or contributing to groundwater nitrate above the 10 mg/L drinking water objective or otherwise affecting beneficial uses. The draft would have state water board staff develop a groundwater loading limit and a land application formula before 2032. The Central Valley board would then use that work to adopt final dairy discharge requirements within seven to eight years.
In the meantime, the regional board would have to adopt interim dairy requirements within three to four years, carry forward the existing 1.4 application-to-removal ratio as an immediate requirement, and set progressively tighter interim limits. The draft also floats whole-farm nitrogen balance as a preferred milestone.
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For farmers, the near-term burden would start with more data. Within 90 days of adoption, the regional board would have to seek depth estimates for manure retention ponds. Within a year, it would issue orders for more precise nitrogen applied and removed measurements and begin requiring dairies to show ponds are not hydraulically connected to groundwater or prepare upgrades. Within two years, the board would require on-farm drinking water well monitoring.
The draft also elevates safe drinking water obligations, including alternative water supplies for impacted residents and potential cleanup orders for dairies outside management zones.
Dairy Cares, a coalition of dairy cooperatives, processors and trade groups, warned the revised order could significantly change how dairies are regulated and accelerate the loss of family-owned farms.
“We are reviewing the draft order carefully and will provide detailed comments during the public review period,” said Michael Boccadoro, the coalition’s executive director, in a statement. “Our immediate concern is what this might mean for the future of our dwindling dairy sector here in the state.”
Boccadoro said some proposals appear achievable, but others look “impractical, costly and onerous,” with expensive changes required on short timelines. He argued the state needs a more balanced approach that allows dairies to continue improving environmental performance without pushing more operations out of California.
Dairy Cares pointed to industry efforts to fund nonprofit well testing and safe drinking water programs, saying more than 4,100 wells have been tested and nearly 2,500 households are receiving free drinking water. The group also cited the CDFA Manure Recycling and Innovative Products Task Force and the Dairy Plus program, which has awarded $44 million for projects that reduce greenhouse gases and improve water quality, with another $31 million expected.
The state water board plans a July 8 workshop and will take written comments through July 30. Adoption is tentatively set for September.
