Nitrate and nitrite
Twisp Town Of
Nitrate and nitrite enter water from fertilizer runoff, septic tanks and urban runoff. These contaminants can cause oxygen deprivation for infants and increase the risk of cancer. Nitrite is significantly more toxic than nitrate. Click here to read more about nitrate.
12
Samples
0
Samples exceeding legal limit (MCL)
12
Samples exceeding
health guidelines
Testing results - average by year
| Year | Average result | Samples taken | Detections | Range of results |
|---|---|---|---|---|
| 2014 | 0.375 ppm | 2 | 2 | 0.280 ppm - 0.470 ppm |
| 2015 | 0.300 ppm | 2 | 2 | 0.300 ppm |
| 2016 | 0.400 ppm | 2 | 2 | 0.290 ppm - 0.510 ppm |
| 2017 | 0.595 ppm | 2 | 2 | 0.590 ppm - 0.600 ppm |
| 2018 | 0.430 ppm | 2 | 2 | 0.420 ppm - 0.440 ppm |
| 2019 | 0.475 ppm | 2 | 2 | 0.460 ppm - 0.490 ppm |
ppm = parts per million
State and national drinking water standards and health guidelines
EWG Health Guideline 0.14 ppm
The 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
ppm = parts per million
All test results
| Date | Lab ID | Result |
|---|---|---|
| 2014-10-29 | 28326 | 0.470 ppm |
| 2014-10-29 | 28327 | 0.280 ppm |
| 2015-09-15 | 28103 | 0.300 ppm |
| 2015-09-15 | 28102 | 0.300 ppm |
| 2016-09-06 | 0.510 ppm | |
| 2016-09-06 | 0.290 ppm | |
| 2017-09-28 | 0.600 ppm | |
| 2017-09-28 | 0.590 ppm | |
| 2018-09-27 | 0.440 ppm | |
| 2018-09-27 | 0.420 ppm | |
| 2019-12-03 | 0.490 ppm | |
| 2019-12-03 | 0.460 ppm |