Nitrate
Bear Mountain Water Supply
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 |
|---|---|---|---|---|
| 2018 | 0.136 ppm | 1 | 1 | 0.136 ppm |
| 2019 | ND | 1 | 0 | ND |
| 2020 | 0.0177 ppm | 3 | 1 | ND - 0.0530 ppm |
| 2021 | ND | 1 | 0 | ND |
| 2022 | 0.116 ppm | 1 | 1 | 0.116 ppm |
| 2023 | 0.129 ppm | 1 | 1 | 0.129 ppm |
ppm = parts per million
State, National, and Health Guidelines for Drinking Water
EWG Health Guideline: 0.14 ppm
The EWG health guideline of 0.14 parts per million, or ppm, for nitrate and nitrite is based on the equivalent health guideline for nitrate, as defined in a peer-reviewed scientific study by EWG. This guideline represents a one-in-one-million annual cancer risk level.
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 |
|---|---|---|
| 2018-01-31 | NO3 01311808-1 | 0.136 ppm |
| 2019-12-26 | NO3 12261906: 1 | ND |
| 2020-07-01 | NO3 07012010A: 9 | 0.0530 ppm |
| 2020-07-01 | NO3 07012010A: 10 | ND |
| 2020-07-01 | NO3 07012010A: 6 | ND |
| 2021-12-28 | NO3 12282107 | ND |
| 2022-12-08 | NO3 12082213 | 0.116 ppm |
| 2023-11-29 | NO3 11292307 | 0.129 ppm |