By Eric M. Johnson

SEATTLE (Reuters) - Washington state Governor Jay Inslee on Wednesday warned billions of dollars in automatic spending cuts could hamper the U.S. government's ability to clean up the Hanford Nuclear Reservation site in his state, where six underground tanks were last week revealed to be leaking.

Inslee, a Democrat who took office last month, said the six single-shell tanks at the decommissioned nuclear plant near the Columbia River in southern Washington state could leak about 1,000 gallons (3,785 liters) of radioactive sludge annually.

That is in line with the latest U.S. Department of Energy (DoE) estimate released this week, which said the six tanks were leaking at a rate of less than 3 gallons a day.

"These tanks, we were told by the federal government, were stabilized years ago. We know that is not the case," Inslee told reporters in Washington state capital Olympia. "The federal government has a legally binding obligation to both remove this material and to make sure we curb this leakage."

The Department of Energy did not immediately return calls seeking comment but has previously said the government is committed to cleaning up the site.

The 586-square-mile nuclear site was established near the town of Hanford in 1943 as part of the Manhattan Project, the U.S. government program that developed the first atomic bombs.

Weapons production at the site resulted in more than 43 million cubic yards of radioactive waste and 130 million cubic yards of contaminated soil and debris, according to the U.S. Environmental Protection Agency (EPA).

Oversight of cleaning up Hanford is shared between Washington Department of Ecology, the EPA and the Department of Energy, but the money behind it almost entirely federal. Continued...