Washington state is suing the federal government again over cleanup at the Hanford Nuclear Reservation — this time over the danger posed to workers by vapor releases from underground waste-storage tanks.

In a federal lawsuit filed Tuesday, state Attorney General Bob Ferguson says the U.S. Department of Energy has known about the problem of vapors sickening workers at the site since the late 1980s, but it hasn't fixed it. There were more than 50 reports of workers being exposed to vapors between January 2014 and April 2015.

"Enough is enough. The health risks are real, and the state is taking action today to ensure the federal government protects these workers now and in the future," Ferguson said in a statement.

In June, the attorney general said he would oppose a U.S. Department of Energy request to have more time to empty the next group of tanks storing waste at Hanford.

Federal officials wanted a one-year extension on its deadline to retrieve radioactive waste from nine leak-prone tanks, which would give them until to fall 2023 to complete the work.

The agency said it needed more time because a recent requirement for air respirators for most workers at the tank farm to protect them against chemical vapors had reduced efficiency by 30 to 70 percent.

The 586-square-mile Hanford nuclear site on the Columbia River in eastern Washington was used to produce plutonium for the U.S. nuclear weapons program from 1943 to 1987. Weapons production left behind large amounts of solid and liquid waste, much of which is radioactive.

Washington Assistant Attorney General Andrew Fitz said the state's job as a Hanford regulator is to hold the Department of Energy accountable, but the history of trying to get tank waste treated for disposal is one of moving deadlines and delays.

A 2010 consent decree resolved a lawsuit filed by the state in 2008 when it became apparent that the Department of Energy could not meet deadlines. The consent decree set new deadlines to be enforced by the court. But now most of the remaining deadlines in the consent decree are at serious risk of being missed by the Department of Energy.