A group of Yakima Valley dairies have agreed to reduce runoff pollution that's tainting the area's groundwater.

The agreement between the dairies and the Environmental Protection Agency was announced Wednesday.

In 2012, an EPA study found that five area dairies were likely polluting private wells with nitrates. About 24,000 in the region use private wells for drinking water.

Under the agreement, the dairies will provide alternative water sources for neighbors within a one-mile radius whose drinking sources have been tainted. The dairies also agree to take steps to control sources of nitrogen, such as manure and commercial fertilizer. They also will conduct soil and groundwater testing at each dairy.

The EPA says the dairies in the agreement are the Cow Palace, George DeRuyter and Son Dairy, D&A Dairy, Liberty Dairy - all located north of Granger and Outlook.