A pollutant that has leached into California aquifers since farmers first began using synthetic fertilizer continues to accumulate and would not be removed from groundwater even if the state’s agriculture businesses abruptly quit using nitrogen-based materials to boost the productivity of their crops.
That’s one of the themes of a new study from the UC Davis Agriculture Sustainability Institute that assesses the scale and sources of a kind of pollution that can harm infants if it seeps into groundwater and contributes to respiratory problems if it drifts into the air as a gas.
The report is the widest look yet at pollution from nitrogen, a common contaminant that the State Water Quality Control Board has tried in fits and starts to remove from Central Valley agricultural communities over the past decade.
The report’s authors offer a range of solutions – from creating a cap-and-trade-style market for nitrogen emissions to encouraging better waste-management practices on farms – but they concede that it could take decades to clean up groundwater that has collected fertilizer runoff since the 1940s.
“We don’t have enough technology on the shelf to be able to address the issue now,” said sustainability institute director Tom Tomich, who led the study. “There’s a need for collaboration with farmers and ranchers to develop solutions to these challenges.”
His team took seven years to weave together a broad picture of nitrogen pollution up and down the state. Past efforts have focused on specific regions, such as a 2012 study that showed up to 250,000 people are highly vulnerable to nitrogen contamination in the Salinas and southern San Joaquin valleys.
Tomich’s study found that California generates about 1.8 million tons of nitrogen every year. More than half of it comes from agricultural sources, which rely on nitrogen as a key component in fertilizers.
Of that, about 419,000 tons leach into groundwater, where it becomes a salt known as nitrate. Overexposure to nitrates in drinking water can hurt an infant’s ability to move oxygen in the bloodstream. It’s a condition known as “blue baby syndrome.”
1.8 million tons Amount of nitrogen released in California every year
In western Stanislaus County, the city of Modesto in 2005 built a special treatment plant to supply water to the small community of Grayson because of nitrate pollution in its wells. Delano in Kern County and Ripon in San Joaquin County also are testing new nitrate-removal processes. McFarland, also in Kern County, has had a nitrate-removal system in its water treatment plant since the 1980s.
“Communities right now are living with nitrogen water. Kids go to school and they’re told not to drink from the taps, and they’re told to buy bottled water,” said Debi Ores, an attorney for the advocacy group Community Water Center. “The problem is the communities are the ones paying the price, not the dischargers.”
Farmers and dairymen had been anticipating the release of the nitrogen assessment for some time. Many are reducing nitrogen pollution by taking steps to prevent fertilizer from going to waste or reforming their manure-management practices. Some effectively reuse nitrogen-polluted groundwater on their crops.
“This is legacy stuff,” said Danny Merkley, director of water resources at the California Farm Bureau. “It’s an issue that is really by no means a product of any nefarious act. It’s literally people doing what they were told and thought was the best practice at the time.”
The report was commissioned in part to determine whether the state should regulate nitrogen emissions as a greenhouse gas. Tomich’s team found that those emissions from agriculture are so small that they likely do not warrant new regulations.
Instead, the team determined that groundwater pollution presented the greatest potential harm to communities. Solving that problem seemed especially difficult because low-income farm communities that are under the most risk also depend on agriculture to support their economies.
“How do we provide safe groundwater for everybody?” Tomich asked. “This is an environmental justice issue. We’re talking about little kids in the Central Valley.”
He’s scheduled to brief legislative staffers on the assessment this fall.
How do we provide safe groundwater for everybody? This is an environmental justice issue. We’re talking about little kids in the Central Valley.
Tom Tomich, director, UC Davis Agriculture Sustainability Institute
The State Water Resources Control Board, meanwhile, is considering new rules for agricultural discharges in the San Joaquin River watershed. A proposal to update the state’s irrigated lands regulatory program is moving forward with provisions for stepped-up monitoring and reporting requirements for farmers.
One controversial item would enable the state to more easily identify which farms are responsible for nitrate pollution.
An early draft of the rules elicited dozens of letters from environmental groups, farmers and farm lobbyists earlier this summer.
Some environmental groups demanded a more rigorous rule, with more penalties for farms with discharge violations. Others asked the board to refine recommendations for fertilizer management, giving farmers goals to hit in reducing nitrate pollution.
“Best practices right now might not help someone this second, but five, 10, 20 years down the road, hopefully we’ll be seeing some benefit,” said Ores, from the Community Water Center.
The majority of the letters came from farmers, who called the proposal a “duplicative” order that would ruin the agency’s hard-earned goodwill with agricultural producers. They asked for more time and more flexibility in managing vital resources for their businesses.
“Water is the lifeblood of all life. Why would we in agriculture not be responsible stewards for water and land in our care?” wrote Stockton rancher Marie Rossi.