Monochloroacetic acid
Nicasio Valley Ranch Mutual
Monochloroacetic acid, one of the group of five haloacetic acids regulated by federal standards, is formed when chlorine or other disinfectants are used to treat drinking water. Haloacetic acids and other disinfection byproducts increase the risk of cancer and may cause problems during pregnancy. Click here to read more about disinfection byproducts.
Samples
Samples exceeding legal limit (MCL)
Samples exceeding
health guidelines
Testing results - average by year
| Year | Average result | Samples taken | Detections | Range of results |
|---|---|---|---|---|
| 2014 | ND | 4 | 0 | ND |
| 2015 | ND | 3 | 0 | ND |
| 2016 | 2.00 ppb | 4 | 3 | ND - 2.95 ppb |
| 2017 | 0.940 ppb | 5 | 1 | ND - 4.70 ppb |
| 2018 | 0.420 ppb | 5 | 1 | ND - 2.10 ppb |
| 2019 | 1.58 ppb | 5 | 1 | ND - 7.90 ppb |
ppb = parts per billion
State and national drinking water standards and health guidelines
EWG Health Guideline 53 ppb
The EWG Health Guideline of 53 ppb for monochloroacetic acid was proposed in 2020 by the California Office of Environmental Health Hazard Assessment as a public health goal, the level of a drinking water contaminant that does not pose a significant health risk.. This health guideline protects against system toxicity.
ppb = parts per billion
All test results
| Date | Lab ID | Result |
|---|---|---|
| 2014-01-09 | 9469-004-1050 | ND |
| 2014-04-25 | 9469-004-1155 | ND |
| 2014-07-17 | 9469-004-1125 | ND |
| 2014-10-16 | 9469-004-1150 | ND |
| 2015-04-16 | 9469-004-1100 | ND |
| 2015-07-16 | 9469-004-1140 | ND |
| 2015-10-09 | 9469-004-1045 | ND |
| 2016-01-21 | 9469-004-1355 | 2.95 ppb |
| 2016-04-14 | 9469-004-1040 | 2.29 ppb |
| 2016-07-15 | 9469-004-1215 | 2.75 ppb |
| 2016-10-12 | 9469-004-1234 | ND |
| 2017-01-17 | 9469-004-1045 | ND |
| 2017-04-13 | 9469-004-1040 | ND |
| 2017-07-12 | 9469-004-1115 | ND |
| 2017-11-03 | 3334-016-1030 | 4.70 ppb |
| 2017-12-14 | 3334-016-1010 | ND |
| 2018-02-08 | 3334-005-1027 | ND |
| 2018-05-03 | 3334-006-1220 | 2.10 ppb |
| 2018-08-09 | 3334-007-1025 | ND |
| 2018-08-30 | 3334-007-1233 | ND |
| 2018-11-02 | 3334-008-1011 | ND |
| 2019-02-07 | 3334-009-1035 | ND |
| 2019-05-02 | 3334-010-1235 | ND |
| 2019-08-22 | 3334-011-1150 | 7.90 ppb |
| 2019-11-07 | 3334-012-0910 | ND |
| 2019-12-17 | 3334-013-0900 | ND |