Nitrate…What is it?
According to the U.S. EPA (United States Environmental Protection Agency) Nitrate (NO3) is defined as “a compound of nitrogen and oxygen naturally found in air, soil, water, and some food. Plants and animals require nitrates for their survival and growth, and the human body also produces this compound. In industry, nitrate is used as fertilizer for crops and lawns. Additionally, nitrates are used in food preservation, certain pharmaceutical medications, as well as the manufacture of munitions and explosives.”
Nitrate is all around us, and the central valley of California is no exception. In ~40% of domestic wells* across parts of Fresno, Kings, and Tulare Counties, nitrate levels are above the safe limit of 10mg/L. EPA’s maximum contaminant level (MCL) for nitrate is set to protect against blue-baby syndrome.
Many communities in the central valley rely on groundwater and some communities cannot safely use groundwater for drinking water due to the high nitrate levels.
*based on results of well testing conducted by the Kings Water Alliance in the Kings subbasin.
Why is Nitrate a problem?
Nitrates seep slowly into the groundwater from leaky septic tanks, fertilizers, or after being discharged as wastewater from animal feedlots, industrial facilities, and/or municipal wastewater plants. In these localized areas, nitrates are a common cause of unsafe drinking water.
Drinking water with high levels of nitrate can create health risks especially to infants, pregnant and nursing women, and elderly people. Nitrate levels have been increased in groundwater over the last several decades. As a result, some private drinking water supplies are unsafe and do not meet government drinking water standards.
What is being done to ensure people living in the central valley have safe drinking water?
A group representing growers, dairies, industries, local communities, environmental organizations, and the State formed the Central Valley Salinity for Long-Term Sustainability (CV-SALTS) in 2006 to work on this water quality issue.
One of the outcomes of this effort is a new Nitrate Control Program with three goals:
The Introduction of Nitrate Management Zones
One of the ways to accomplish the objectives of the Nitrate Control Program was the formation of local Management Zones in 2021 by nitrate dischargers to help families with contaminated wells through free well testing, bottled water deliveries, and fill station locations.
The first management zone covered the Modesto, Turlock, Chowchilla, Kings, Kaweah and Tule subbasins. The second management zones covered Yolo, Tulare Lake, Delta Mendota, eastern San Joaquin, Madera and part of Kern subbasins.
Each management zone has an organization similar to Kings Water Alliance for residents to contact about their drinking water. The Kings Water Alliance is the governing entity for the Kings Management Zone, encompassing the Kings and Tulare Lake groundwater subbasins.
Click any of the logos below to learn more about each Management Zone:
Additional Resources
Nitrate:
Groundwater Information Sheet: Nitrate (State Water Resources Control Board)
Nitrates and Nitrites in Drinking Water Webpage (California Water Boards)
Nitrate Fact Sheet (CA Department of Public Health)
Nitrate Fact Sheet- Short (Central Valley Water Board)
Safe Drinking Water Webpage (CV Salts)
For Domestic Well Owners:
A Guide for Private Domestic Well Owners (State Water Resources Control Board)
