A board has given final approval to rules aimed at protecting groundwater from farm-based pollutants in part of the San Joaquin Valley.
The Central Valley Regional Water Quality Control Board voted unanimously to adopt the rules, which apply to the parts of Stanislaus, Merced and Madera counties east of the San Joaquin River.
The board also agreed, to the approval of agricultural interests, to have the effort carried out by the same farmer-funded coalition that has handled surface water issues for almost a decade.
The group, the East San Joaquin Water Quality Coalition, pays for water testing and educates growers about farming practices that reduce pollution, all under state supervision.
The coalition has reported a decline in detections of pesticides and other pollutants in rivers, creeks and drainage canals.
The groundwater effort is aimed mainly at nitrates from fertilizer and other sources. A recent study by the University of California at Davis says nitrates are a health threat in rural drinking water systems in the Tulare Lake Basin and Salinas Valley.
The coalition has about 2,300 members farming about half of the 1.1 million irrigated acres east of the San Joaquin. Growers who do not take part must get individual permits from the regional board at a much greater cost.
Growers to plan ahead
Parry Klassen, the coalition's executive director, said the new groundwater rules require growers to have plans to manage nitrogen fertilizer on hand. Those found to be in "high vulnerability areas" for nitrates will have to file the plan with the coalition, he said.
Experts urge farmers to keep track of their nitrogen fertilizer -- in part because it could produce nitrates, in part because they save money by reducing the amount spread on the soil.
"Not all that nitrogen is going into the plant," said Michael Johnson, a consultant to the coalition, during a fertilizer conference in Modesto in October. "Where does the rest of it go?"
This group was the first of several coalitions around the Central Valley to be governed by the new groundwater rules. Others could follow next year, including those serving San Joaquin County and the West Side.