Nitrate
City of Sonoma
Nitrate, a fertilizer chemical, frequently contaminates drinking water due to agricultural and urban runoff, and discharges from municipal wastewater treatment plants and septic tanks. Excessive nitrate in water can cause oxygen deprivation in infants and increase the risk of cancer. Click here to read more about nitrate.
Samples
Samples exceeding legal limit (MCL)
Samples exceeding
health guidelines
Testing results - average by year
| Year | Average result | Samples taken | Detections | Range of results |
|---|---|---|---|---|
| 2013 | N/A | 0 | 0 | N/A |
| 2014 | 0.477 ppm | 9 | 7 | ND - 1.27 ppm |
| 2015 | 0.628 ppm | 5 | 4 | ND - 1.49 ppm |
| 2016 | 0.590 ppm | 6 | 5 | ND - 1.60 ppm |
| 2017 | 0.737 ppm | 6 | 6 | 0.120 ppm - 2.10 ppm |
| 2018 | 0.734 ppm | 5 | 5 | 0.140 ppm - 1.70 ppm |
| 2019 | 0.806 ppm | 7 | 7 | 0.150 ppm - 2.40 ppm |
ppm = parts per million
State and national drinking water standards and health guidelines
EWG Health Guideline 0.14 ppm
The EWG Health Guideline of 0.14 ppm for nitrate was defined by EWG . This health guideline protects against cancer and harm to fetal growth and development.
EPA Maximum Contaminant
Level (MCL) 10 ppm
The legal limit for nitrate, established in 1962, was developed to protect infants from acute methemoglobinemia, a life-threatening disorder of oxygen transport in the body. This limit does not fully protect against the risk of cancer and harm to the developing fetus.
ppm = parts per million
All test results
| Date | Lab ID | Result |
|---|---|---|
| 2014-02-04 | 9541-002-1008 | 0.474 ppm |
| 2014-02-10 | 9541-006-1023 | 0.384 ppm |
| 2014-02-18 | 9541-003-1023 | 0.429 ppm |
| 2014-02-25 | 9541-004-0836 | ND |
| 2014-02-25 | 9541-001-0755 | 1.27 ppm |
| 2014-03-17 | 9541-004-0920 | ND |
| 2014-03-17 | 9541-003-0920 | 0.384 ppm |
| 2014-03-18 | 9541-002-1001 | 0.429 ppm |
| 2014-09-03 | 9541-023-0910 | 0.926 ppm |
| 2015-02-17 | 9541-003-0930 | 0.452 ppm |
| 2015-02-24 | 9541-004-1045 | ND |
| 2015-02-24 | 9541-001-1015 | 1.49 ppm |
| 2015-03-09 | 9541-006-0945 | 0.429 ppm |
| 2015-05-13 | 9541-023-0920 | 0.768 ppm |
| 2016-03-29 | 9541-023-0937 | 0.820 ppm |
| 2016-03-29 | 9541-006-1117 | 0.180 ppm |
| 2016-03-29 | 9541-001-0827 | 1.60 ppm |
| 2016-03-29 | 9541-002-0735 | 0.460 ppm |
| 2016-03-29 | 9541-003-0907 | 0.480 ppm |
| 2016-03-31 | 9541-004-0900 | ND |
| 2017-01-30 | 9541-002-0741 | 0.510 ppm |
| 2017-02-06 | 9541-006-0835 | 0.220 ppm |
| 2017-02-13 | 9541-023-0850 | 0.970 ppm |
| 2017-02-13 | 9541-003-0748 | 0.500 ppm |
| 2017-02-21 | 9541-004-0900 | 0.120 ppm |
| 2017-02-21 | 9541-001-0820 | 2.10 ppm |
| 2018-02-12 | 9541-003-0852 | 0.530 ppm |
| 2018-02-12 | 9541-023-0932 | 0.790 ppm |
| 2018-02-20 | 9541-001-0822 | 1.70 ppm |
| 2018-02-20 | 9541-004-0917 | 0.140 ppm |
| 2018-02-26 | 9541-002-0742 | 0.510 ppm |
| 2019-01-31 | 9541-002-1020 | 0.520 ppm |
| 2019-02-20 | 9541-004-1153 | 0.150 ppm |
| 2019-02-20 | 9541-001-1038 | 2.40 ppm |
| 2019-03-01 | 9541-002-1111 | 0.490 ppm |
| 2019-03-11 | 9541-023-1032 | 0.960 ppm |
| 2019-03-11 | 9541-003-1143 | 0.590 ppm |
| 2019-09-04 | 9541-002-1208 | 0.530 ppm |