EWG's Tap Water Database — 2019 UPDATE



City of Black Hawk

Nitrate, a fertilizer chemical, frequently contaminates drinking water due to agricultural and urban runoff, and discharges from municipal wastewater treatment plants and septic tanks. Excessive nitrate in water can cause oxygen deprivation in infants and increase the risk of cancer. Click here to read more about nitrate.





Samples exceeding legal limit (MCL)


Samples exceeding
health guidelines

Testing results - average by year

YearAverage resultSamples takenDetectionsRange of results
20120.175 ppm220.120 ppm - 0.230 ppm
20130.280 ppm220.140 ppm - 0.420 ppm
20140.305 ppm220.210 ppm - 0.400 ppm
20150.255 ppm220.160 ppm - 0.350 ppm
20160.375 ppm220.360 ppm - 0.390 ppm
20170.295 ppm220.170 ppm - 0.420 ppm

ppm = parts per million

State and national drinking water standards and health guidelines

EWG Health Guideline 0.14 ppm

The EWG Health Guideline of 0.14 ppm for nitrate was defined by EWG . This health guideline protects against cancer and harm to fetal growth and development.

EPA Maximum Contaminant
Level (MCL) 10 ppm

The legal limit for nitrate, established in 1962, was developed to protect infants from acute methemoglobinemia, a life-threatening disorder of oxygen transport in the body. This limit does not fully protect against the risk of cancer and harm to the developing fetus.

ppm = parts per million

All test results

Date Result
2012-05-080.230 ppm
2012-06-270.120 ppm
2013-02-050.420 ppm
2013-02-190.140 ppm
2014-03-040.210 ppm
2014-03-040.400 ppm
2015-05-120.350 ppm
2015-07-130.160 ppm
2016-02-230.360 ppm
2016-03-070.390 ppm
2017-01-240.170 ppm
2017-02-070.420 ppm