Nitrate and nitrite
Rockport Colony
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.
87
Samples
9
Samples exceeding legal limit (MCL)
78
Samples exceeding
health guidelines
Testing results - average by year
| Year | Average result | Samples taken | Detections | Range of results |
|---|---|---|---|---|
| 2014 | ND | 1 | 0 | ND |
| 2015 | 4.58 ppm | 1 | 1 | 4.58 ppm |
| 2016 | 4.56 ppm | 1 | 1 | 4.56 ppm |
| 2017 | 2.25 ppm | 4 | 4 | 0.920 ppm - 3.69 ppm |
| 2018 | 5.55 ppm | 56 | 55 | ND - 26.8 ppm |
| 2019 | 0.427 ppm | 24 | 21 | ND - 1.52 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 |
|---|---|---|
| 2014-02-25 | H14020313-001A | ND |
| 2015-02-02 | H15020043-001B | 4.58 ppm |
| 2016-02-09 | H16020147-001B | 4.56 ppm |
| 2017-02-21 | H17020294-001A | 3.69 ppm |
| 2017-05-31 | H17060027-001A | 2.58 ppm |
| 2017-07-19 | H17070333-001A | 0.920 ppm |
| 2017-11-06 | H17110188-001B | 1.80 ppm |
| 2018-02-07 | H18020158-001B | 22.0 ppm |
| 2018-02-15 | H18020263-003A | ND |
| 2018-02-15 | H18020263-001A | 3.02 ppm |
| 2018-02-15 | H18020263-002A | 8.90 ppm |
| 2018-02-15 | H18020263-004A | 11.3 ppm |
| 2018-02-15 | H18020263-005A | 9.90 ppm |
| 2018-02-27 | H18020404-003A | 22.5 ppm |
| 2018-02-27 | H18020404-002A | 26.8 ppm |
| 2018-02-27 | H18020404-001A | 7.20 ppm |
| 2018-03-13 | H18030228-004A | 7.72 ppm |
| 2018-03-13 | H18030228-003A | 0.210 ppm |
| 2018-03-13 | H18030228-002A | 4.06 ppm |
| 2018-03-13 | H18030228-001A | 2.59 ppm |
| 2018-03-22 | H18030356-003A | 12.3 ppm |
| 2018-03-22 | H18030356-001A | 6.06 ppm |
| 2018-03-22 | H18030356-002A | 3.26 ppm |
| 2018-03-22 | H18030356-004A | 9.57 ppm |
| 2018-03-29 | H18030488-004A | 13.2 ppm |
| 2018-03-29 | H18030488-003A | 12.0 ppm |
| 2018-03-29 | H18030488-002A | 3.20 ppm |
| 2018-03-29 | H18030488-001A | 7.70 ppm |
| 2018-04-03 | H18040061-001A | 1.38 ppm |
| 2018-04-03 | H18040061-002A | 0.1000 ppm |
| 2018-04-03 | H18040061-003A | 11.1 ppm |
| 2018-04-03 | H18040061-004A | 14.1 ppm |
| 2018-04-03 | H18040061-005A | 0.230 ppm |
| 2018-05-15 | H18050381-004A | 1.89 ppm |
| 2018-05-15 | H18050381-003A | 1.87 ppm |
| 2018-05-15 | H18050381-002A | 0.360 ppm |
| 2018-05-15 | H18050381-001A | 3.90 ppm |
| 2018-06-03 | H18060051-004A | 1.95 ppm |
| 2018-06-03 | H18060051-003A | 2.00 ppm |
| 2018-06-03 | H18060051-002A | 0.500 ppm |
| 2018-06-03 | H18060051-001A | 4.00 ppm |
| 2018-07-15 | H18070344-003A | 0.580 ppm |
| 2018-07-15 | H18070344-005A | 6.40 ppm |
| 2018-07-15 | H18070344-004A | 7.00 ppm |
| 2018-07-15 | H18070344-002A | 4.81 ppm |
| 2018-07-15 | H18070344-001A | 5.40 ppm |
| 2018-08-05 | H18080106-005A | 7.48 ppm |
| 2018-08-05 | H18080106-004A | 9.14 ppm |
| 2018-08-05 | H18080106-003A | 8.80 ppm |
| 2018-08-05 | H18080106-002A | 0.870 ppm |
| 2018-08-05 | H18080106-001A | 3.07 ppm |
| 2018-09-05 | H18090087-002A | 0.480 ppm |
| 2018-09-05 | H18090087-001A | 4.24 ppm |
| 2018-09-06 | H18090087-003A | 2.48 ppm |
| 2018-10-14 | H18100391-003A | 0.260 ppm |
| 2018-10-14 | H18100391-002A | 4.08 ppm |
| 2018-10-14 | H18100391-001A | 1.87 ppm |
| 2018-11-06 | H18110188-003A | 0.210 ppm |
| 2018-11-06 | H18110188-002A | 2.36 ppm |
| 2018-11-06 | H18110188-001A | 1.22 ppm |
| 2018-12-05 | H18120114-003A | 0.280 ppm |
| 2018-12-05 | H18120114-002A | 1.86 ppm |
| 2018-12-05 | H18120114-001A | 0.930 ppm |
| 2019-01-08 | H19010124-002A | 0.220 ppm |
| 2019-01-08 | H19010124-001A | 1.49 ppm |
| 2019-01-08 | H19010124-003A | 0.890 ppm |
| 2019-02-06 | H19020279-003A | 0.290 ppm |
| 2019-02-06 | H19020279-002A | 1.52 ppm |
| 2019-02-06 | H19020279-001A | 0.760 ppm |
| 2019-03-10 | H19030123-003A | 0.160 ppm |
| 2019-03-10 | H19030123-002A | 1.03 ppm |
| 2019-03-10 | H19030123-001A | 0.580 ppm |
| 2019-04-02 | H19040089-003A | 0.0500 ppm |
| 2019-04-02 | H19040089-002A | 0.750 ppm |
| 2019-04-02 | H19040089-001A | 0.430 ppm |
| 2019-05-14 | H19050415-003A | 0.280 ppm |
| 2019-05-14 | H19050415-001A | 0.290 ppm |
| 2019-05-14 | H19050415-002A | ND |
| 2019-06-11 | H19060358-003A | 0.280 ppm |
| 2019-06-11 | H19060358-002A | ND |
| 2019-06-11 | H19060358-001A | 0.160 ppm |
| 2019-07-09 | H19070190-003A | 0.0400 ppm |
| 2019-07-09 | H19070190-002A | 0.430 ppm |
| 2019-07-09 | H19070190-001A | 0.240 ppm |
| 2019-08-13 | H19080403-001A | 0.140 ppm |
| 2019-08-13 | H19080403-003A | 0.220 ppm |
| 2019-08-13 | H19080403-002A | ND |