Six underground radioactive waste tanks at Hanford,  the nation's most contaminated nuclear site are leaking.

Inslee made the announcement after meeting with federal officials in Washington, D.C. Last week it was revealed that one of the 177 tanks at south-central Washington's Hanford Nuclear Reservation was leaking liquids. Inslee called the latest news "disturbing."

The tanks, which already are 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.

The U.S. Department of Energy said earlier that liquid levels were decreasing in one of the tanks at the site. Monitoring wells near the tank have not detected higher radiation levels.

The federal government created Hanford in the 1940s as part of the top-secret Manhattan Project to build the atomic bomb. The government spends $2 billion each year on Hanford cleanup — one-third of its entire budget for nuclear cleanup nationally. The cleanup is expected to last decades.

Central to cleanup is the construction of a plant to convert millions of gallons of waste into glasslike logs for safe, secure storage. The $12.3 billion plant is billions of dollars over budget and behind schedule.

Inslee and Oregon Gov. John Kitzhaber have championed building additional tanks to ensure safe storage of the waste until the plant is completed. Democratic Sen. Ron Wyden of Oregon said earlier this week that he shares their concerns about the integrity of the tanks, but that he wants more scientific information to determine it's the correct way to spend scarce money.

Wyden noted the nation's most contaminated nuclear site — and the challenges associated with ridding it of its toxic legacy — will be a subject of upcoming hearings and a higher priority in Washington D.C.