After a more than a year of testing, dairies in Washington’s Lower Yakima Valley are trying to reduce water pollution from manure. A report from the Environmental Protection Agency had found the dairies were likely sources of nitrate pollution to nearby residential wells.
The EPA is presenting its findings from the testing at a meeting Thursday in Granger, Washington.
When nitrates contaminate drinking water, they can cause birth defects and miscarriages and harm the health of some adults.
Water was tested from residential wells located in the direction where dairy-polluted groundwater flows. The data show 61 percent of those wells exceeded the maximum standard for nitrates. That’s five times higher than residential wells in the rest of the Yakima Valley.
Several dairies in the Lower Yakima Valley signed a consent order with the EPA in March, 2013, agreeing to control nitrate pollution. The dairies will continue monitoring wells and collecting data for eight years, when they hope to see a downward trend in nitrate levels.
“We don’t expect the groundwater to clean up overnight. It will take some time,” said Eric Winiecki, the EPA’s project coordinator for the Lower Yakima Valley investigation unit.