Groundwater Quality

California has enacted many different initiatives that to ensure long-term groundwater quality. Key among these are regulations governing salt and nitrate management in California’s South San Joaquin Valley.

Photo credit: Salt concentrate puddle on rocky ground, iStock 1003043296
Photo credit: Salt concentrate puddle on rocky ground, iStock 1003043296
  • The Central Valley Salinity Coalition (CVSC) was created as a non-profit member organization in 2008 to assist with implementing the SNMP into the basin plans, as well as to manage salts and nitrates in the Central Valley. The SNMP will be implemented through amendments to the Water Quality Control Plans (Basin Plans) for each managed basin in the Central Valley region (Region 5).

  • The Recycled Water Policy, adopted in 2009, directs individual water and wastewater entities to prepare SNMPs to protect groundwater within their subbasins. These entities were given until May 2016 to develop their individual SNMPs, with the input and assistance from CV-SALTS.

  • Final Central Valley-wide SNMP (Final Plan)[1] was released in January 2017. The CV-RWQCB held a hearing in March 2017 to receive public comments and consider a resolution accepting the Final Plan. As a result of public input, CV-SALTS released amendments to the Final Plan[2] that were presented during a public workshop in January, 2018. The public comment period for the amended plan just ended (May 7, 2018). The next hearing is scheduled for May 31-June 1, 2018 to receive public comments and consider adoption of the Central Valley-wide SNMP.

    In addition to the SNMP, dairy processing facilities must comply with Order R5-2013-0122 (Dairy Order)[3], which was originally issued in 2007 and reissued in 2013.

Photo credit: Tractor spreading chemical fertiliser, iStock 619272282
Photo credit: Tractor spreading chemical fertiliser, iStock 619272282
  • SWRCB Resolution No. 88-63, “Sources of Drinking Water” policy of 1988 specifies that all surface and ground waters are suitable or potentially suitable for MUN beneficial uses except under specially defined exceptions.

  • Resolution R5-2017-0088, scheduled for potential adoption in 2018, intends to incorporate a MUN evaluation process for agriculturally dominated water bodies, allowing reuse of groundwater supplies that exceed the Maximum Contaminant Level for Municipal and Domestic Supply (MUN MCL) in facilities with no existing or potential MUN use.

  • Senate Bill X2 1 required the SWRCB to develop pilot projects focusing on nitrate in groundwater in the Tulare Lake Basin and Salinas Valley. SBX2 1 also “required the SWRCB to submit a report to the Legislature on the scope and findings of the pilot projects, including recommendations, within two years of receiving funding.”

    “In response to SBX2 1, the State Water Board contracted with the University of California, Davis (UC Davis) in 2010 to conduct an independent study on nitrates in the Tulare Lake Basin and the Salinas Valley. The UC Davis Nitrate Report, comprised of volumes 1-8, was delivered to the State Water Board in March 2012.” The study was supplemented in 2017 with the results of a 5-year field study (conducted from January 2012 through December 2014, and August 2015 through June 2016) about Nitrogen Fertilizer Loading to Groundwater in the Central Valley.

  • Proposed Salt and Nitrate Control Program (SNCP) is intended to facilitate implementation of strategies for targeted restoration of groundwater quality. The components of the SNCP that relate specifically to nitrates include providing two pathways for dischargers to comply with nitrate discharge limits. Path A is an individual discharger permitting approach, and Path B is a management zone permitting approach. A management zone would consist of multiple dischargers working collectively to ensure safe drinking water and balanced nitrate loading in the short- and long-term. Other components include the following:

Uses data from the CVHM to determine priority groundwater basins for implementation of the Nitrate Control Program. Dischargers in Priority 1 basins will be notified within one year of the effective date of the amendments. Dischargers in Priority 2 basins will be notified within two to four years. The remaining basins will be prioritized at the discretion of the Central Valley Water Board.

All permittees discharging nitrate pursuant to Board-issued waste discharge requirements and conditional waivers will be prohibited from discharging upon receiving a notice to comply unless they are implementing the requirements of the Nitrate Control Program. Dischargers regulated under the Irrigated Lands Regulatory Program (ILRP) will instead be required to comply with the Nitrate Control Program through an amendment to the ILRP General Orders, which the Regional Water Board shall consider within 18 months of the effective date of the Basin Plan Amendment.

The Salt and Nitrate Surveillance and Monitoring Program will periodically assess the effectiveness of the Salinity and Nitrate Control Programs, and develop representative ambient water quality and trend information. Data will come from dischargers’ monitoring efforts, regional monitoring programs conducted by state and federal agencies, or from special studies evaluating effectiveness of management practices. A summary report will be submitted to the Board every five years.

The Regional Water Board may authorize a discharge that may violate applicable water quality standards in the receiving groundwater basin provided safe drinking water is provided to users of the nitrate-contaminated water. Exceptions are only used when it is not feasible to prohibit the discharge, and the discharger has no feasible way to meet the water quality objectives in a specified time period. Exceptions are time-bound and periodically reviewed.

The proposed Basin Plan Amendment recommends an Offsets Policy of salt and nitrate to groundwater, which would allow dischargers to comply with waste discharge requirements by managing other sources or loads so that the combined net effect on receiving water quality from the discharge and the offset is functionally equivalent to or better than that which would have occurred by requiring the discharger to comply at the point-of-discharge.

  • Dairy Order R5-2013-0122 was adopted in 2007 and reissued in 2013 and is the existing regulation affecting water and nutrient discharge of dairy facilities. The Dairy Order specifies dairy-specific actions needed to ensure surface and groundwater quality. Each discharger who applies manure, bedding, or process wastewater to land for nutrient recycling must develop and implement management practices that control nutrient losses and describe these in a Nutrient Management Plan (NMP)[4] which must provide for protection of both surface water and groundwater.

    Under the Dairy Order, individual dischargers are obligated to apply their nutrient-rich manure and process water at agronomic rates[5]. If they have insufficient land to apply at agronomic rates, they have a few options to achieve compliance with the requirements of the Dairy Order:

    1. Export some of their manure/process water.
    2. Buy or lease more cropland.
    3. Reduce their herd size.
    4. Install or modify facilities or equipment.
Photo credit: Dairy cattle, Shutterstock 659176180
Photo credit: Dairy cattle, Shutterstock 659176180
BPTC is the term used by the SWRCB for compliance with provisions of the federal Clean Water Act, that establish limits on the quality of effluent discharges on the basis of “Best Practicable Control Technology Currently Available” (BPT). The U.S. Environmental Protection Agency’s “BPT” benchmark requires consideration of multiple factors, including:“—the total cost of applying the control technology in relation to the effluent reduction benefits
  • age of the equipment and facilities
  • processes employed by the industry and any required process changes
  • engineering aspects of the control technologies
  • non-water quality environmental impacts, including energy requirements
  • other factors as EPA deems appropriate”

“Traditionally, EPA establishes BPT effluent limitations based on the average of the best performance of facilities within the industry of various ages, sizes, processes or other common characteristics. Where existing performance is uniformly inadequate, BPT may reflect higher levels of control than currently in place in an industrial category if the Agency determines that the technology can be practically applied.”

Source: “Effluent Guidelines,” USEPA website:

These and similar practices are considered to be Best Practicable Treatment or Control (BPTC) to minimize degradation.

The Dairy Order defines expansion as any increase in the existing herd size (>15%), or an increase in the storage capacity of retention ponds, or acquisition of more acreage for reuse of nutrients from manure or process wastewater in order to accommodate an expansion of the existing herd size. Expansions are not authorized as part of the Dairy Order, so any expansion requires dischargers to submit a Report of Waste Discharge (ROWD), document compliance with the California Environmental Quality Act (CEQA), and obtain coverage under individual waste discharge requirements. Acquisition of additional acreage to achieve compliance with the Dairy Order where it is not accommodating an expansion of the existing herd size is not considered an expansion, and so is not subject to these requirements.

The Dairy Order specifies nutrient monitoring processes:

Nutrient application rates are to be monitored for each land application area, defined as land under control of the milk cow dairy owner or operator, whether it is owned, rented, or leased, to which manure or process wastewater from the production area is or may be applied for nutrient recycling.

[1] Central Valley Salinity Alternatives for Long-Term Sustainability (CV-SALTS). Central Valley Region Salt and Nitrate Management Plan, Final Document for Central Valley Water Board Consideration. 2016.

[2] California Regional Water Quality Control Board, Central Valley Region. Amendments to the Water Quality Control Plans for the Sacramento River and San Joaquin River Basins and Tulare Lake Basin to Incorporate a Central Valley-Wide Salt and Nitrate Control Program. 2018.

[3] California Regional Water Quality Control Board, Central Valley Region. Reissued Waste Discharge Requirements General Order for Existing Milk Cow Dairies. (Order R5-2013-0122). 2013.

[4] “Managing the amount (rate), source, placement (method of application), and timing of plant nutrients and soil amendments.” Source: Natural Resources Conservation Service, U.S. Department of Agriculture (October 2013). Conservation Practice Standard, Code 590: Nutrient Management. Retrieved from NRCS website:

[5] “Agronomic rates” is defined as the land application of irrigation water and nutrients (which may include animal manure, bedding, or process wastewater) at rates of application in accordance with a plan for nutrient management that will enhance soil productivity and provide the crop or forage growth with needed nutrient for optimum health and growth. The rate is defined by the applied-to-removed ratio for Nitrogen, targeting a ratio of 1.4 and the amount removed is measured by plant tissue sampling during harvest. Sources: Dale Essary, Senior Engineer, Confined Animals Unit, Central Valley Water Board, & Central Valley Water Board, Dairy Plan: