The Benton-Franklin Health District is offering free nitrate screening Thursday for Benton County residents with private wells.
Well owners can bring two cups of well water, obtained before any treatment, in a clean glass or plastic container, from 11 a.m. to 2 p.m. to the Mid-Columbia Library, 902 Seventh St., Prosser.
Nitrate contamination is a byproduct of fertilizer and animal waste and is known to contaminate many wells in rural Benton County, said a health district release.
Nitrates have been found in drinking water in many counties along the Columbia and Yakima rivers. Nitrate levels above 10 parts per million are considered unsafe for pregnant women and infants under 6 months.
Nitrate pollution in drinking water has been linked to birth defects, miscarriages and blue baby syndrome. Livestock also can be harmed.
While public water supplies are tested routinely for nitrate contamination, private domestic wells are not.