State officials are inching closer to understanding the scale of nitrate pollution in Eastern Oregon drinking water. That is after the state released data that pinpoints the location of where contamination is found in the region, but local advocates say the map fails to protect residents’ privacy.

The Oregon Health Authority released updated data, including four maps, that show the scale of nitrate contamination in domestic well water in Morrow and Umatilla counties. Groundwater in the region has been polluted with nitrate contamination for more than 30 years. It was designated a groundwater management area in 1990 known as the Lower Umatilla Basin Groundwater Management Area or LUBGWMA.

If ingested at levels of more than 10 milligrams per liter, nitrate contamination can cause health effects like respiratory infections, thyroid dysfunction and stomach or bladder cancer, according to the Environmental Protection Agency.