Nitrate and nitrite
Marin Municipal Water District
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.
Testing results - average by year
Year | Average result | Samples taken | Detections | Range of results |
---|---|---|---|---|
2013 | N/A | 0 | 0 | N/A |
2014 | 0.200 ppm | 12 | 6 | ND - 0.400 ppm |
2015 | 0.338 ppm | 12 | 9 | ND - 0.680 ppm |
2016 | 0.0975 ppm | 12 | 2 | ND - 0.700 ppm |
2017 | 0.0783 ppm | 12 | 2 | ND - 0.500 ppm |
2018 | ND | 12 | 0 | ND |
2019 | 0.0825 ppm | 12 | 2 | ND - 0.570 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 |
---|---|---|
2014-02-03 | 7747-011-0850 | ND |
2014-02-03 | 7747-005-0845 | 0.400 ppm |
2014-02-03 | 7747-004-1140 | ND |
2014-05-05 | 7747-011-0915 | ND |
2014-05-05 | 7747-005-1200 | 0.400 ppm |
2014-05-05 | 7747-004-1125 | ND |
2014-08-04 | 7747-011-0940 | 0.400 ppm |
2014-08-04 | 7747-004-1155 | ND |
2014-08-05 | 7747-005-1320 | 0.400 ppm |
2014-11-03 | 7747-011-1240 | 0.400 ppm |
2014-11-03 | 7747-005-1230 | 0.400 ppm |
2014-11-03 | 7747-004-1350 | ND |
2015-02-02 | 7747-004-1310 | 0.400 ppm |
2015-02-02 | 7747-011-0750 | 0.400 ppm |
2015-02-04 | 7747-005-0845 | 0.680 ppm |
2015-05-04 | 7747-011-1325 | 0.520 ppm |
2015-05-04 | 7747-004-0945 | 0.400 ppm |
2015-05-04 | 7747-005-0815 | 0.430 ppm |
2015-08-03 | 7747-004-0945 | ND |
2015-08-03 | 7747-005-1320 | 0.400 ppm |
2015-08-03 | 7747-011-1205 | 0.400 ppm |
2015-11-02 | 7747-004-0920 | ND |
2015-11-02 | 7747-005-0810 | ND |
2015-11-02 | 7747-011-1155 | 0.420 ppm |
2016-02-01 | 7747-004-0850 | ND |
2016-02-01 | 7747-011-1205 | ND |
2016-02-02 | 7747-005-1035 | 0.700 ppm |
2016-05-02 | 7747-011-0840 | ND |
2016-05-02 | 7747-004-1045 | ND |
2016-05-02 | 7747-005-0840 | 0.470 ppm |
2016-08-01 | 7747-004-0845 | ND |
2016-08-01 | 7747-011-1145 | ND |
2016-08-01 | 7747-005-0800 | ND |
2016-11-07 | 7747-004-0925 | ND |
2016-11-07 | 7747-011-1150 | ND |
2016-11-07 | 7747-005-0705 | ND |
2017-02-06 | 7747-004-1015 | ND |
2017-02-06 | 7747-011-0755 | ND |
2017-02-06 | 7747-005-1035 | 0.500 ppm |
2017-05-01 | 7747-005-0800 | 0.440 ppm |
2017-05-01 | 7747-004-1150 | ND |
2017-05-01 | 7747-011-0750 | ND |
2017-08-07 | 7747-005-0800 | ND |
2017-08-07 | 7747-004-1140 | ND |
2017-08-07 | 7747-011-0900 | ND |
2017-11-06 | 7747-004-1200 | ND |
2017-11-06 | 7747-011-0920 | ND |
2017-11-06 | 7747-005-0930 | ND |
2018-02-07 | 7747-004-1105 | ND |
2018-02-07 | 7747-011-0945 | ND |
2018-02-07 | 7747-005-1245 | ND |
2018-05-07 | 7747-005-0800 | ND |
2018-05-07 | 7747-004-0905 | ND |
2018-05-07 | 7747-011-0920 | ND |
2018-08-06 | 7747-004-0915 | ND |
2018-08-06 | 7747-005-0810 | ND |
2018-08-06 | 7747-011-1045 | ND |
2018-11-05 | 7747-011-1045 | ND |
2018-11-05 | 7747-005-0940 | ND |
2018-11-05 | 7747-004-0845 | ND |
2019-02-04 | 7747-011-1135 | ND |
2019-02-04 | 7747-004-1045 | ND |
2019-02-04 | 7747-005-0930 | 0.570 ppm |
2019-05-06 | 7747-011-0910 | ND |
2019-05-06 | 7747-005-0730 | 0.420 ppm |
2019-05-09 | 7747-004-1050 | ND |
2019-08-05 | 7747-011-0845 | ND |
2019-08-05 | 7747-004-1250 | ND |
2019-08-05 | 7747-005-0730 | ND |
2019-11-04 | 7747-011-0810 | ND |
2019-11-04 | 7747-005-0730 | ND |
2019-11-04 | 7747-004-1240 | ND |