The Power of Information

National Drinking Water Database

Nitrate & nitrite in California

Nitrate and nitrite enter water from fertilizer runoff, leaching from septic tanks, and erosion of natural deposits.

The Most Polluted Communities in California

877 water utilities reported detecting Nitrate & nitrite in tap water since 2004, according to EWG's analysis of water quality data supplied by state water agencies

Ranked by highest average Nitrate & nitrite level

RankSystem Population Served Positive test results of total reported tests Average Level
1Tony Morris / Morris Dairy
Modesto, CA
2412 of 1223.57 ppm
(17.74 to 28.39 ppm)
2LA Verne, City Wd
La Verne, CA
34,0098 of 817.54 ppm
(12 to 22 ppm)
3Farmers Labor Exchange
Gilroy, CA
1501 of 114.74 ppm
(14.74 ppm)
4Salinas Valley State Prison
Soledad, CA
5,2001 of 114.69 ppm
(14.69 ppm)
5Tico Mutual Water Co
Oak View, CA
1051 of 113.8 ppm
(13.8 ppm)
6County Water of Riverside
Elsinore, CA
1803 of 313 ppm
(10 to 18 ppm)
7Soults Mutual Water Co.
Tulare, CA
1001 of 113 ppm
(13 ppm)
8Feather River Manor
Arboga, CA
351 of 112.9 ppm
(12.9 ppm)
9Golden State Water Company - Tanglewood
San Dimas,, CA
1,4982 of 212.53 ppm
(8.75 to 16.3 ppm)
10Double R Trailer Park
Desert Hot Springs, CA
901 of 112 ppm
(12 ppm)

Health Based Limits for Nitrate & nitrite

Maximum Contaminant Limit (MCL)The enforceable standard which defines the highest level of a contaminant that is allowed in drinking water. MCLs are set as close to health-based limits (Maximum Contaminant Level Goals, or MCLGs) as feasible using the best available analytical and treatment technologies and taking cost into consideration. Source: U.S. Environmental Protection Agency.10 ppm
Maximum Contaminant Limit Goal (MCLG)A non-enforceable health goal that is set at a level at which no known or anticipated adverse effect on the health of persons occurs and which allows an adequate margin of safety. Source: U.S. Environmental Protection Agency.10 ppm
California Public Health GoalsDefined by the State of California Office of Environmental Health Hazard Assessment (OEHHA) as the level of contaminant that is allowed in drinking water. For acutely toxic substances, levels are set at which scientific evidence indicates that no known or anticipated adverse effects on health will occur, plus an adequate margin-of safety. PHGs for carcinogens or other substances which can cause chronic disease shall be based solely on health effects without regard to cost impacts and shall be set at levels which OEHHA has determined do not pose any significant risk to health.10 ppm

Violation Summary for Nitrate & nitrite in California

Data from the U.S. Environmental Protection Agency includes the following violations of federal standards in California since 2004

Violation TypeNumber of Violations
Failure to monitor regularly2
Failure to monitor: Check/Repeat/Confirmation sampling1