A recent Environmental Protection Agency (EPA) study focused on investigating nitrate contamination of private drinking water wells across the Lower Valley near Yakima, Wash., has pointed to local dairies as the likely culprits, according to the Yakima Herald-Republic.

The 307-page report, released by EPA on Thursday, looked at contributing factors in the area’s well contamination. Though the study was limited and cannot provide a conclusive source of the contamination, officials singled out five local dairies as the likely cause. Even with the possible link, the report’s authors admit that the region’s entire nitrate contamination problem cannot be blamed solely on the dairies.

"The dairies that we sampled are the only ones we could draw this conclusion about because we didn’t look at all the dairies," said Mike Cox, an EPA scientist.

The report concluded that immediate action is needed to reduce the level of nitrates in the wells, which could take years due to the extent of the contamination. Officials do not expect the dairies to face any fines. The report’s findings have been criticized by many in the dairy industry who claim that, among other things, the researchers did not take any septic systems or different soil types into account.

Private wells are used exclusively by the 24,000 residents living in the unincorporated areas of the Lower Valley as the primarily source of drinking water, and after sampling 331 of these residential wells, the EPA discovered that 20 percent had nitrate levels above federal drinking water standards. Excessive nitrates have the potential of harming infants and those with compromised immune systems.

Read more from the Yakima Herald-Republic.