By Christine Souza, Ag Alert
As California water officials consider changes to the state’s regulatory framework for nitrogen applications and discharges by farms that irrigate, those representing growers who rely on nitrogen fertilizers say more data and time are needed before strict targets are imposed.
Kari Fisher, senior counsel and director of legal advocacy for the California Farm Bureau, said it is premature to adopt nitrogen applied and nitrogen removed limits at this time. She added that the industry is still gathering and evaluating data to develop realistic nitrogen targets that work for all crops in all regions.
“We have found that the one-size-fits-all nitrogen and application reporting requirements don’t necessarily fit with how agriculture is grown in the state because of differences related to commodity type, where crops are grown and reliance on surface water versus groundwater and the like,” Fisher said.
Composed of University of California scientists and Cooperative Extension specialists, the second statewide agricultural expert panel is tasked with reassessing and updating the state’s regulatory approach to reduce nitrates.
The panel met twice this month to review nitrogen reporting data collected as part of the state’s Irrigated Lands Regulatory Program, or ILRP, which governs how regional agricultural orders manage farm runoff.
The first statewide agricultural expert panel was convened in 2014 to evaluate nitrate control programs and develop recommendations to protect groundwater quality. This led to the state’s precedential 2018 East San Joaquin water quality order that required all regional boards to update ILRPs to comply.
At a second meeting of the expert panel held Aug. 14, Karen Mogus, chief deputy director of the California State Water Resources Control Board, said even though much progress has been made since the first expert panel, “we have a lot more to do.”
New key issues raised stem from the Central Coast Regional Water Quality Control Board’s Ag Order 4.0, which established limits and targets for nitrogen applications and discharges.
Elaine Sahl, ILRP manager for the Central Coast Regional Water Quality Control Board, said the region has collected a significant amount of nitrogen reporting data supplied by growers since 2012. She said the data show “there’s significant nitrogen loading occurring in ranches that grow lettuce.”
In discussing the issue, Monterey County Farm Bureau Executive Director Norm Groot told Ag Alert® that Central Coast farmers acknowledge that past nitrogen use has affected groundwater quality, but improved agronomics have allowed growers to manage fertilizer use more efficiently.
“The expert panel should look at current fertilizer practices, follow the science and realize that nitrogen is integral to the production of our food crops in a competitive marketplace,” he said. “Artificially limiting nitrogen use will decrease yields, force some change of crops or reduce production cycles and impact our nation’s food supply.”
With so much at stake, Groot suggested the expert panel collect multiple years of data before making strict recommendations on nitrogen use in agricultural production.
Eric Warren, ILRP program manager for the Central Valley Regional Water Quality Control Board, said the region has enrolled 5.4 million acres into the ILRP and has 14 coalitions. Many economic factors dictate the number of acres and types of crops that are planted in any given year, he said.
“We are making progress,” Warren said. “Even in the absence of enforceable numeric limits, growers have reported a 30% reduction in (nitrogen) loading, and we’re hoping to see that trend continue.”
Looking ahead, Warren said more time is needed to collect more data and learn more about the interaction between management practices and nitrogen loading outcomes, and soil and climate interactions in different parts of the region.
“We do see really significant value in the existing irrigation and nitrogen management planning process and grower education,” Warren said.
Central Valley farmer and attorney David Cory said as growers get more familiar with completing nitrogen reports, the reporting information is improving with fewer errors.
“It’s important that we have stability in reporting so growers can understand what they’re doing and get used to that format,” he said.
Kalee Popovich, environmental scientist at the San Diego Regional Water Quality Control Board, said the county has many types of diversified farms that grow many crops.
“A grower in this category may be growing avocados in an orchard, aboveground planters for vegetables and a greenhouse on site for temperature-sensitive, smaller plants,” Popovich said.
Due to the crop diversity of multicrop operations, she said nitrogen calculations may not be straightforward and suggested that the region needs more information and assistance from the expert panel to implement reporting requirements.
Santa Clara University professor Iris Stewart-Frey cited a 2012 nitrate report by UC Davis professors Thomas Harter and Jay Lund that assessed public health hazards associated with nitrates in drinking water.
“The longer we wait, the higher the nitrate contaminations and the cost any remediation and mitigation effort is likely to become,” she said.
She told the panel that science-based nitrogen limits should be established and asked that academic experts analyze data—particularly for the Central Coast and Central Valley—before the October meeting.
The second agricultural expert panel is scheduled to meet Oct. 31 and Jan. 14.
“This is a really important process for the future of irrigated agriculture in the state of California,” California Farm Bureau’s Fisher said. “People should definitely be engaged.”
Learn more about the process at https://waterboards.ca.gov/water_issues/programs/agriculture/2025-expert-panel.html.
Christine Souza is senior editor of Ag Alert. She can be reached at csouza@cfbf.com.
