Know Your Environment. Protect Your Health.

Chlorate

Lake Sherwood Community Services District

Chlorate forms in drinking water as a byproduct of disinfection. Chlorate impairs thyroid function, making chlorate exposure most harmful during pregnancy and childhood. Read More.

In 2002, California scientists proposed an advisory value, called an action level, for chlorate at 200 parts per billion. Between 2013 and 2015, the EPA collected data through the Unregulated Contaminant Monitoring Rule program and found that over 15 percent of water tests from 38 percent of utilities had chlorate levels above a health-protective concentration, which federal scientists defined as 210 parts per billion, nearly equivalent to the California advisory value.

Click here to read more about disinfection byproducts.

 

8

Samples

0

Samples exceeding legal limit (MCL)

0

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
20139.00 ppb83ND - 30.0 ppb
2014N/A00N/A
2015N/A00N/A
2016N/A00N/A
2017N/A00N/A
2018ND20ND
2019ND20ND
2020ND20ND
2021ND10ND
2022ND10ND
2023ND10ND

ppb = parts per billion

State, National, and Health Guidelines for Drinking Water

EWG Health Guideline: 210 ppb

The EWG Health Guideline of 210 ppb for chlorate was defined by the Environmental Protection Agency as a benchmark for testing under the Unregulated Contaminant Monitoring Rule program. This health guideline protects against hormone disruption.

ppb = parts per billion

All test results

Date Lab ID Result
2013-03-19100574QND
2013-03-19300660PND
2013-06-17101508QND
2013-06-17301442PND
2013-09-17302033P22.0 ppb
2013-09-17102108F30.0 ppb
2013-12-17102828QND
2013-12-17302761P20.0 ppb