PORTLAND, Ore. – A federal court has ruled that the U.S. Environmental Protection Agency must come up with a plan to protect salmon from warm water temperatures, which can be fatal for the fish species.

Record-high water temperatures in rivers across the Pacific Northwest in 2015 led environmental groups to sue the agency.

That summer, around 250,000 adult sockeye died in the Columbia and Snake rivers.

The threatened and endangered salmon and steelhead can die if water gets above 70 degrees.

The Wednesday ruling says dams are a big reason rivers get too warm.

The EPA now must figure out how to minimize the impact of the dams on water temperature. The agency has 30 days to respond to the court’s ruling.