Nitrate and nitrite
Regional Water Authority
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.
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 | 1.26 ppm | 27 | 27 | 0.0900 ppm - 3.79 ppm |
| 2019 | 1.48 ppm | 26 | 26 | 0.0200 ppm - 3.80 ppm |
| 2020 | 1.35 ppm | 29 | 29 | 0.0340 ppm - 3.63 ppm |
| 2021 | 1.11 ppm | 115 | 115 | 0.0140 ppm - 4.15 ppm |
| 2022 | 0.258 ppm | 15 | 9 | ND - 1.16 ppm |
| 2023 | 0.490 ppm | 20 | 17 | ND - 3.47 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
ppm = parts per million
All test results
| Date | Lab ID | Result |
|---|---|---|
| 2018-03-12 | IOCR 200489760 | 2.43 ppm |
| 2018-03-12 | IOCR 200489758 | 0.757 ppm |
| 2018-03-12 | IOCR 200489759 | 3.02 ppm |
| 2018-03-14 | IOCR 200489911 | 0.380 ppm |
| 2018-03-14 | NOX 200489867 | 2.47 ppm |
| 2018-03-14 | NOX 200489870 | 2.70 ppm |
| 2018-03-14 | NOX 200489868 | 1.04 ppm |
| 2018-03-14 | NOX 200489884 | 0.114 ppm |
| 2018-03-14 | NOX 200489885 | 0.270 ppm |
| 2018-03-14 | NOX 200489871 | 0.388 ppm |
| 2018-03-14 | NOX 200489913 | 0.414 ppm |
| 2018-03-14 | NOX 200489914 | 0.947 ppm |
| 2018-03-14 | IOCR 200489898 | 1.72 ppm |
| 2018-03-14 | IOCR 200489900 | 3.24 ppm |
| 2018-03-14 | IOCR 200489896 | 1.15 ppm |
| 2018-03-14 | IOCR 200489912 | 0.930 ppm |
| 2018-03-14 | IOCR 200489886 | 0.0900 ppm |
| 2018-03-14 | IOCR 200489887 | 0.240 ppm |
| 2018-03-14 | IOCR 200489872 | 0.373 ppm |
| 2018-03-14 | IOCR 200489897 | 0.972 ppm |
| 2018-03-15 | NOX 200490061 | 2.97 ppm |
| 2018-03-15 | IOCR 200490062 | 3.79 ppm |
| 2018-03-15 | IOCR 200490063 | 0.577 ppm |
| 2018-03-23 | IOCR 200490512 | 0.665 ppm |
| 2018-11-29 | NOX 200514097 | 0.872 ppm |
| 2018-11-29 | NOX 200514112 | 0.732 ppm |
| 2018-11-29 | IOCR 200514114 | 0.849 ppm |
| 2019-03-18 | NOX 200524895 | 1.17 ppm |
| 2019-03-18 | IOCR 200524896 | 3.37 ppm |
| 2019-03-18 | IOCR 200524903 | 3.80 ppm |
| 2019-03-18 | IOCR 200524901 | 1.31 ppm |
| 2019-03-18 | IOCR 200524902 | 3.07 ppm |
| 2019-03-18 | IOCR 200524905 | 0.981 ppm |
| 2019-03-18 | IOCR 200524900 | 1.48 ppm |
| 2019-03-19 | IOCR 200525095 | 0.526 ppm |
| 2019-03-19 | NOX 200525057 | 2.58 ppm |
| 2019-03-19 | NOX 200525060 | 3.72 ppm |
| 2019-03-19 | NOX 200525058 | 1.44 ppm |
| 2019-03-19 | NOX 200525059 | 3.10 ppm |
| 2019-03-19 | NOX 200525077 | 0.0200 ppm |
| 2019-03-19 | NOX 200525078 | 0.0510 ppm |
| 2019-03-19 | NOX 200525061 | 0.316 ppm |
| 2019-03-19 | NOX 200525097 | 0.491 ppm |
| 2019-03-19 | NOX 200525098 | 0.791 ppm |
| 2019-03-19 | IOCR 200525065 | 1.76 ppm |
| 2019-03-19 | IOCR 200525066 | 3.73 ppm |
| 2019-03-19 | IOCR 200525064 | 1.52 ppm |
| 2019-03-19 | IOCR 200525096 | 0.813 ppm |
| 2019-03-19 | IOCR 200525079 | 0.0480 ppm |
| 2019-03-19 | IOCR 200525080 | 0.0640 ppm |
| 2019-03-19 | IOCR 200525062 | 0.290 ppm |
| 2019-05-08 | NOX 200531297 | 0.986 ppm |
| 2019-05-08 | IOCR 200531303 | 1.01 ppm |
| 2020-02-10 | NOX 200565460 | 1.02 ppm |
| 2020-02-10 | IOCR 200565461 | 3.63 ppm |
| 2020-02-10 | IOCR 200565469 | 3.28 ppm |
| 2020-02-10 | IOCR 200565466 | 1.06 ppm |
| 2020-02-10 | IOCR 200565467 | 3.03 ppm |
| 2020-02-10 | IOCR 200565470 | 1.07 ppm |
| 2020-02-11 | NOX 200565624 | 2.69 ppm |
| 2020-02-11 | NOX 200565625 | 0.830 ppm |
| 2020-02-11 | NOX 200565627 | 2.98 ppm |
| 2020-02-11 | NOX 200565625A | 0.830 ppm |
| 2020-02-11 | NOX 200565626 | 3.04 ppm |
| 2020-02-11 | NOX 200565593 | 0.0340 ppm |
| 2020-02-11 | NOX 200565594 | 0.193 ppm |
| 2020-02-11 | NOX 200565628A | 0.257 ppm |
| 2020-02-11 | NOX 200565616 | 0.708 ppm |
| 2020-02-11 | NOX 200565617 | 1.11 ppm |
| 2020-02-11 | IOCR 200565632 | 1.66 ppm |
| 2020-02-11 | IOCR 200565633 | 3.37 ppm |
| 2020-02-11 | IOCR 200565631 | 2.77 ppm |
| 2020-02-11 | NOX 200565628 | 0.257 ppm |
| 2020-02-11 | IOCR 200565595 | 0.0350 ppm |
| 2020-02-11 | IOCR 200565596 | 0.179 ppm |
| 2020-02-11 | IOCR 200565629 | 0.243 ppm |
| 2020-02-12 | IOCR 200565847 | 0.646 ppm |
| 2020-02-12 | IOCR 200565848 | 0.884 ppm |
| 2020-08-10 | IOCR 200585597 | 0.629 ppm |
| 2020-08-11 | NOX 200585733 | 0.880 ppm |
| 2020-08-11 | IOCR 200585735 | 0.933 ppm |
| 2020-08-11 | IOCR 200585736 | 0.913 ppm |
| 2021-02-08 | IOCR 200605858 | 4.15 ppm |
| 2021-02-08 | IOCR 200605854 | 0.769 ppm |
| 2021-02-08 | IOCR 200605856 | 0.944 ppm |
| 2021-02-08 | IOCR 200605852 | 2.98 ppm |
| 2021-02-08 | IOCR 200605855 | 0.973 ppm |
| 2021-02-09 | NOX 200606114 | 3.73 ppm |
| 2021-02-09 | NOX 200606111 | 2.88 ppm |
| 2021-02-09 | NOX 200606110 | 0.920 ppm |
| 2021-02-09 | NOX 200606109 | 2.93 ppm |
| 2021-02-09 | NOX 200605956 | 1.27 ppm |
| 2021-02-09 | NOX 200605886 | 0.0820 ppm |
| 2021-02-09 | NOX 200605888 | 0.233 ppm |
| 2021-02-09 | NOX 200605959 | 1.23 ppm |
| 2021-02-09 | IOCR 200606115 | 3.31 ppm |
| 2021-02-09 | IOCR 200606112 | 2.64 ppm |
| 2021-02-09 | IOCR 200606113 | 3.23 ppm |
| 2021-02-09 | IOCR 200605957 | 1.32 ppm |
| 2021-02-09 | IOCR 200605958 | 0.961 ppm |
| 2021-02-09 | IOCR 200605931 | 1.13 ppm |
| 2021-02-09 | NOX 200606116 | 0.285 ppm |
| 2021-02-09 | IOCR 200605887 | 0.0540 ppm |
| 2021-02-09 | IOCR 200605960 | 1.28 ppm |
| 2021-02-09 | IOCR 200605889 | 0.209 ppm |
| 2021-02-09 | IOCR 200606117 | 0.268 ppm |
| 2021-02-10 | IOCR 200606359 | 1.41 ppm |
| 2021-02-10 | IOCR 200606356 | 0.843 ppm |
| 2021-02-17 | IOCR 200606910 | 0.367 ppm |
| 2021-09-20 | N300062460 300062463 | 0.0430 ppm |
| 2021-09-20 | N300062466 300062469 | 0.0400 ppm |
| 2021-09-20 | N300062475 300062478 | 0.0390 ppm |
| 2021-09-20 | N300062500 300062503 | 0.0430 ppm |
| 2021-09-20 | N300062713 300062716 | 0.0370 ppm |
| 2021-09-20 | N300062724 300062727 | 3.47 ppm |
| 2021-09-20 | N300062698 300062701 | 3.19 ppm |
| 2021-09-20 | N300062683 300062686 | 2.27 ppm |
| 2021-09-20 | N300062689 300062692 | 2.74 ppm |
| 2021-09-20 | N300062662 300062665 | 0.729 ppm |
| 2021-09-20 | N300062674 300062677 | 0.926 ppm |
| 2021-09-20 | N300062652 300062655 | 2.89 ppm |
| 2021-09-20 | N300062668 300062671 | 0.770 ppm |
| 2021-09-21 | N300062817 300062820 | 0.0440 ppm |
| 2021-09-21 | N300062862 300062865 | 0.0330 ppm |
| 2021-09-21 | N300062874 300062877 | 0.0360 ppm |
| 2021-09-21 | N300062797 300062800 | 2.64 ppm |
| 2021-09-21 | N300062791 300062794 | 2.43 ppm |
| 2021-09-21 | N300062785 300062788 | 0.960 ppm |
| 2021-09-21 | N300062779 300062782 | 2.85 ppm |
| 2021-09-21 | N300062758 300062761 | 0.971 ppm |
| 2021-09-21 | N300062892 300062895 | 0.0280 ppm |
| 2021-09-21 | N300062905 300062908 | 0.0500 ppm |
| 2021-09-21 | N300062803 300062806 | 0.0720 ppm |
| 2021-09-21 | N300064199 300064202 | 1.41 ppm |
| 2021-09-21 | N300064205 300064208 | 0.960 ppm |
| 2021-09-21 | N300062764 300062767 | 1.02 ppm |
| 2021-09-21 | N300062770 300062774 | 0.994 ppm |
| 2021-09-21 | N300062898 300062902 | 0.0140 ppm |
| 2021-09-21 | N300062912 300062916 | 0.0220 ppm |
| 2021-09-21 | N300062810 300062814 | 0.0510 ppm |
| 2021-09-22 | N300064359 300064362 | 0.0420 ppm |
| 2021-09-22 | N300064371 300064374 | 0.951 ppm |
| 2021-09-22 | N300064777 300064780 | 0.0260 ppm |
| 2021-09-22 | N300064783 300064786 | 0.0290 ppm |
| 2021-09-22 | N300064789 300064792 | 0.0420 ppm |
| 2021-09-22 | N300064341 300064344 | 3.55 ppm |
| 2021-09-23 | N300066513 300066516 | 0.377 ppm |
| 2021-09-23 | N300066525 300066528 | 1.80 ppm |
| 2021-09-28 | N300068432 300068435 | 0.0240 ppm |
| 2021-09-29 | N300070521 300070524 | 0.594 ppm |
| 2021-10-18 | N300082865 300082868 | 0.534 ppm |
| 2021-10-18 | N300082872 300082876 | 0.735 ppm |
| 2021-12-06 | N300112518 300112521 | 0.0370 ppm |
| 2021-12-06 | N300112626 300112629 | 0.0580 ppm |
| 2021-12-06 | N300112635 300112638 | 0.0330 ppm |
| 2021-12-06 | N300112644 300112647 | 0.0310 ppm |
| 2021-12-06 | N300112669 300112672 | 0.0320 ppm |
| 2021-12-06 | N300112543 300112546 | 3.53 ppm |
| 2021-12-06 | N300112503 300112506 | 3.32 ppm |
| 2021-12-06 | N300112488 300112491 | 2.32 ppm |
| 2021-12-06 | N300112494 300112497 | 3.03 ppm |
| 2021-12-06 | N300112475 300112478 | 3.20 ppm |
| 2021-12-06 | N300112549 300112552 | 0.581 ppm |
| 2021-12-07 | N300112776 300112779 | 0.0310 ppm |
| 2021-12-07 | N300112788 300112791 | 0.0310 ppm |
| 2021-12-07 | N300113019 300113022 | 0.0910 ppm |
| 2021-12-07 | N300113213 300113216 | 0.683 ppm |
| 2021-12-07 | N300112999 300113002 | 3.43 ppm |
| 2021-12-07 | N300112992 300112996 | 0.945 ppm |
| 2021-12-07 | N300113807 300113810 | 3.14 ppm |
| 2021-12-07 | N300112806 300112809 | 0.0340 ppm |
| 2021-12-07 | N300112819 300112822 | 0.158 ppm |
| 2021-12-07 | N300113005 300113008 | 0.111 ppm |
| 2021-12-07 | N300113025 300113030 | 0.618 ppm |
| 2021-12-07 | N300113056 300113059 | 3.31 ppm |
| 2021-12-07 | N300113062 300113065 | 0.902 ppm |
| 2021-12-07 | N300112812 300112816 | 0.0180 ppm |
| 2021-12-07 | N300113034 300113038 | 0.928 ppm |
| 2021-12-07 | N300112826 300112830 | 0.133 ppm |
| 2021-12-07 | N300113012 300113016 | 0.110 ppm |
| 2021-12-07 | N300113068 300113071 | 0.993 ppm |
| 2021-12-08 | N300113983 300113986 | 0.0290 ppm |
| 2021-12-08 | N300113989 300113992 | 0.0280 ppm |
| 2021-12-08 | N300113995 300113998 | 0.0300 ppm |
| 2021-12-08 | N300114092 300114095 | 2.17 ppm |
| 2021-12-08 | N300114127 300114130 | 0.106 ppm |
| 2021-12-08 | N300114139 300114142 | 2.73 ppm |
| 2021-12-08 | N300114133 300114136 | 1.42 ppm |
| 2021-12-09 | N300115069 300115072 | 0.325 ppm |
| 2021-12-09 | N300116072 300116075 | 1.32 ppm |
| 2021-12-09 | N300116078 300116081 | 1.47 ppm |
| 2021-12-09 | N300116084 300116087 | 1.06 ppm |
| 2021-12-14 | N300113228 300113231 | 0.746 ppm |
| 2021-12-14 | N300113222 300113225 | 0.767 ppm |
| 2021-12-14 | N300113234 300113237 | 1.05 ppm |
| 2021-12-14 | N300113253 300113256 | 0.302 ppm |
| 2021-12-14 | N300113240 300113243 | 1.08 ppm |
| 2022-02-15 | N300145541 300145544 | ND |
| 2022-02-15 | N300145532 300145535 | ND |
| 2022-02-15 | N300145523 300145526 | ND |
| 2022-02-15 | N300145514 300145517 | ND |
| 2022-02-15 | N300146276 300146279 | ND |
| 2022-02-15 | N300145647 300145650 | 0.0340 ppm |
| 2022-02-15 | N300145667 300145670 | 0.308 ppm |
| 2022-02-15 | N300145550 300145553 | 0.180 ppm |
| 2022-02-15 | N300145575 300145578 | ND |
| 2022-02-15 | N300145699 300145702 | 0.712 ppm |
| 2022-02-15 | N300145718 300145721 | 1.16 ppm |
| 2022-02-15 | I300145657 300145660 | 0.0390 ppm |
| 2022-02-15 | I300145585 300145588 | 0.964 ppm |
| 2022-02-15 | I300145677 300145680 | 0.286 ppm |
| 2022-02-15 | I300145560 300145563 | 0.186 ppm |
| 2023-02-07 | I300305807 300305810 | 0.0300 ppm |
| 2023-05-09 | N300346683 300346686 | ND |
| 2023-05-09 | N300346677 300346680 | ND |
| 2023-05-09 | N300346671 300346674 | 0.922 ppm |
| 2023-05-09 | N300346754 300346757 | 1.36 ppm |
| 2023-05-09 | N300346689 300346692 | 0.149 ppm |
| 2023-05-09 | N300346708 300346711 | 0.760 ppm |
| 2023-05-09 | N300346714 300346718 | 0.681 ppm |
| 2023-05-09 | N300346695 300346699 | 0.127 ppm |
| 2023-05-10 | N300347601 300347604 | 0.791 ppm |
| 2023-05-10 | N300347613 300347616 | 0.955 ppm |
| 2023-05-23 | N300354085 300354088 | ND |
| 2023-05-23 | N300354099 300354102 | 0.1000 ppm |
| 2023-05-23 | N300354092 300354096 | 0.00500 ppm |
| 2023-05-23 | N300354106 300354110 | 0.0840 ppm |
| 2023-08-15 | N300397643 300397646 | 3.47 ppm |
| 2023-08-15 | I300398155 300398159 | 0.00800 ppm |
| 2023-08-15 | I300397686 300397690 | 0.271 ppm |
| 2023-08-15 | I300398169 300398173 | 0.0710 ppm |
| 2023-08-15 | I300397667 300397671 | 0.0150 ppm |