Although agricultural runoff often contains dissolved salts, pathogens, and sediments from soil erosion, the most serious water quality degradation in California is caused by excessive fertilizer and pesticide use.
Over 600,000 tons of nitrogen fertilizer are applied to the fields every year, yet crops use, on average, only a third to half of the nitrogen applied. The rest enters waterbodies, resulting in algae blooms, fish kills, and restriction of recreational uses. Nitrogen also leaches into groundwater. Hundreds of thousands of residents in agricultural areas draw their drinking water from untreated wells with potential nitrate contamination, which has been linked with blue-baby syndrome in infants, birth defects, and various cancers. Often these low-income communities cannot afford alternative water supplies.
Pesticides sprayed on fields can be acutely toxic to freshwater and marine life. While two common pesticides, diazinon and chlorpyrifos, have been largely banned by the U.S. Environmental Protection Agency, they enjoy an exemption for agricultural uses. Many waterbodies have been listed as impaired due to pesticides.
California’s regulatory structure
Unlike the federal Clean Water Act, which does not regulate nonpoint sources such as agricultural runoff, California’s Porter-Cologne Act covers any discharge activity that could affect the quality of surface water, wetlands, or groundwater. Agricultural nonpoint discharges may be regulated through general or site-specific permits called waste discharge requirements, waivers of waste discharge requirements, or prohibitions.
The nine Regional Water Quality Control Boards assume primary enforcement responsibility for permits and local water quality control plans—called basin plans—which set water quality standards needed to protect the beneficial use of local waterbodies.
Fulfilling section 319 of the Clean Water Act, California has a nonpoint source program plan that identifies sources of pollution and methods to control those sources. Its nonpoint source policy is incorporated into basin plans that must achieve water quality objectives, describe best management practices, include a specific time schedule and quantifiable milestones, and set out clear requirements for verification and enforcement.
Permits and basin plans must also comply with California’s antidegradation policy, which complements federal antidegradation regulations. This state policy limits discharges that will degrade “existing high quality waters,” defined as waters of better quality than the established water quality objectives.
Shift from general waivers to general permits
Beginning in the 1980s, agricultural runoff was generally covered by blanket waivers. The state legislature, in 1999, and again in 2003, amended the Porter-Cologne Act to require that the next generation of waivers comply with basin plans, include monitoring provisions, and expire after a five-year term.
Several regional boards, including the Central Coast, Los Angeles, Central Valley, and Colorado River regional boards, have since developed conditional waivers for wastewater from agricultural lands. These waivers have focused on (1) gathering data about on-farm practices, (2) aggregated reporting, and (3) tiering that places more stringent requirements on a small group of growers in the highest-risk tier. The Central Coast, a major agricultural region between Los Angeles and San Francisco, has relied on waivers since 2004 and, most recently, in 2017, readopted a prior waiver, despite a court’s rejection of the prior waiver.
The Central Valley, covering the majority of California’s agricultural lands, is at the forefront of a statewide shift from general waivers to general permits. The State Water Board is developing a new set of permits. Unlike general waivers that cover agriculture for an entire region for a five-year term, these new permits are tailored to specific geographic areas, such as the East San Joaquin valley, or to commodities, and they have no expiration date. The State Water Board has declared that these permits will be “precedential” for the state. It has also initiated a statewide Irrigated Lands Regulatory Program to coordinate the efforts of the nine regional boards.
Despite these efforts aimed at better regulating agricultural runoff, in the words of the Central Coast regional board, “pollution gets substantially worse each year, and the actual numbers of polluted wells and people affected are unknown.”
California has a regulatory patchwork for agricultural runoff, with some regions lacking any regulation, some covered by general waivers, and some covered by subregional permits. Regardless of the type of regulatory mechanism, California has yet to develop an approach to agricultural runoff that includes enforceable measures that ensure progress toward meeting water quality objectives.
One challenge is specifying effective nitrate controls for on-farm application; the regional boards largely rely on education campaigns and self-reporting. Some regional boards require that growers report the total nitrogen applied but have yet to cap nitrate applied for specific crops based on crop uptake. Permits could impose conditions on the timing and application rates of fertilizer and irrigation water to precisely match crop needs (known as nitrate balancing), i.e., set a maximum of “x” pounds of fertilizer per acre of lettuce.
Another challenge is specifying adequate monitoring to identify problem polluters, given infrequent monitoring stations and the reliance on grower reporting, done in the aggregate. Permits could require monitoring stations spaced at minimum distances and public reporting of discharges from individual farms. The highly anticipated Central Valley permits may be a bellwether to gauge whether California will finally impose effective controls on nitrates and pesticides.