Irrigated Lands Regulatory Program

California agriculture is extremely diverse and spans a wide array of growing conditions from northern to southern California. California's agriculture includes more than 400 commodities. The state produces nearly half of US-grown fruits, nuts and vegetables. Across the nation, US consumers regularly purchase crops produced in California. Many of the products are exported to markets worldwide.

Water discharges from agricultural operations in California include irrigation runoff, flows from tile drains, and storm water runoff. These discharges can affect water quality by transporting pollutants, including pesticides, sediment, nutrients, salts (including selenium and boron), pathogens, and heavy metals, from cultivated fields into surface waters. Many surface water bodies are impaired because of pollutants from agricultural sources. Groundwater bodies have suffered pesticide, nitrate, and salt contamination.

To prevent agricultural discharges from impairing the waters that receive these discharges, the Irrigated Lands Regulatory Program (ILRP) regulates discharges from irrigated agricultural lands. This is done by issuing waste discharge requirements (WDRs) or conditional waivers of WDRs (Orders) to growers. These Orders contain conditions requiring water quality monitoring of receiving waters and corrective actions when impairments are found. The number of acres of agricultural land enrolled in the ILRP is about six million acres. The number of growers enrolled is approximately 40,000.


On February 7, 2018, the State Water Resources Control Board adopted an order revising agricultural requirements for the Eastern San Joaquin River Watershed to reduce nitrate contamination of groundwater and surface water.

Following extensive public comment and expert input, the order is aimed at protecting communities that rely on groundwater for their drinking water.  Nitrate contamination of drinking water is a widespread problem that poses serious public health risks. Nitrates can also have adverse impacts on surface water and aquatic ecosystems.

The order also directs protections for surface water and groundwater quality from other chemicals, including fertilizers, herbicides, and pesticides that many be found in agricultural discharges.

The order revises waste discharge requirements for the Eastern San Joaquin River Watershed issued by the Central Valley Regional Water Quality Control Board in 2012.  The watershed comprises an area of about one million acres of irrigated agriculture in the eastern San Joaquin Valley.

The order also establishes a model for all regional water boards to follow in their subsequent orders to reduce pollutants from irrigated agriculture around the State.  The order directs the regional water boards to revise their agricultural orders to incorporate testing of drinking water quality for on-farm wells and address the long-term goal of improving groundwater and surface water quality through monitoring and controlling agricultural practices, specifically nitrogen management.

To improve monitoring of nitrogen impacts, the order directs the regional water boards to require the reporting of nitrogen application to crops from fertilizers, organic soil amendments, and in irrigation water, as well as data on nitrogen removed when crops are harvested and taken from the fields.

To protect people presently using on-farm drinking water wells, starting in 2019, the order requires that growers monitor for nitrate levels in on-farm drinking water supply wells and notify the users of those wells if water is found to be above drinking water standards. This provision will come into effect if there are no statewide programs requiring the testing of domestic wells by January 1, 2019.

Many of the changes the order incorporates are recommendations from the following: a nitrogen tracking task force and an agricultural expert panel convened as a result of legislation [Chapter 1 of the Second Extraordinary Session of 2008 (SBX2 1, Perata)]; a Board-adopted Report to the Legislature that made recommendation on how to address nitrates in drinking water, and the Board’s previous order from 2013 regarding a petition of the Central Coast Regional Water Board’s agricultural regulatory program.

Nitrate-SBX2 1 Expert Panel

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