The Associated Press

Washington state Gov. Jay Inslee, right, is joined by Maia Bellon, director of the Department of Ecology, at a news conference to discuss a tank leak at Hanford Nuclear Reservation, on Friday, Feb. 15, 2013, in Olympia, Wash. The U.S. Department of Energy said liquid levels are decreasing in one of 177 underground tanks, but that higher radiation levels have not been detected. (AP Photo/Rachel La Corte)

By SHANNON DININNY and MIKE BAKER Associated Press

OLYMPIA, Wash. (AP) — The long-delayed cleanup of the nation’s most contaminated nuclear site became the subject of more bad news Friday, when Washington Gov. Jay Inslee announced that a radioactive waste tank there is leaking.

The news raises concerns about the integrity of similar tanks at south-central Washington’s Hanford nuclear reservation and puts added pressure on the federal government to resolve construction problems with the plant being built to alleviate environmental and safety risks from the waste.

The tanks, which are already long past their intended 20-year life span, hold millions of gallons of a highly radioactive stew left from decades of plutonium production for nuclear weapons.

On Friday, the U.S. Department of Energy said liquid levels are decreasing in one of 177 underground tanks at the site. Monitoring wells near the tank have not detected higher radiation levels, but Inslee said the leak could be in the range of 150 gallons to 300 gallons over the course of a year and poses a potential long-term threat to groundwater and rivers.