A federal judge approved a precedent-setting order Friday requiring the U.S. Department of Energy to be subject to Ohio environmental regulations in a $1 billion cleanup of the agency's Fernald uranium processing plant.

Ohio Attorney General Anthony Celebrezze Jr. and Sen. John Glenn, D-Ohio, said the decree, negotiated by federal and state attorneys, is historic because it gives the state a court-enforceable order to pressure the Energy Department to clean up the plant. Celebrezze and Glenn said it is the first such agreement they know of.Celebrezze and Richard Shank, the Ohio Environmental Protection Agency director, said Ohio will use the order to force the Energy Department to clean up the plant and pay for its cost, estimated at $1 billion.

U.S. District Judge S. Arthur Spiegel signed the agreement Friday morning in Cincinnati, Celebrezze said.

The accord covers the Feed Materials Production Center in Fernald, which state officials blame for contamination of air and water at the 1,050-acre site 18 miles north of Cincinnati. The plant enriches uranium for nuclear power plants and for the government's nuclear research efforts.

The announcement of the agreement Thursday came as the plant's operator announced plans to lay off 350 workers because of decreased demand for its product.