The U.S. Department of Energy has halted cleanup of radiation-contaminated facilities at the Santa Susana Field Laboratory for 45 days, officials announced Thursday.

The cleanup of the last two facilities in the lab's nuclear research area was under way despite a federal judge's May 2 order that directed the Energy Department to complete a full environmental impact statement for the 2,850-acre site in the hills south of Simi Valley.

The revelation that work was still under way had sparked a whirlwind of activity at both the federal and state levels, with DOE fielding calls from federally elected officials and correspondence from the California agency overseeing chemical cleanup at the lab.

During the 45-day period, Energy Department officials will continue to perform environmental monitoring activities, work with state and federal regulators and evaluate the department's cleanup strategy, DOE spokesman Bill Taylor said.

It is unclear whether the DOE will begin work on an environmental study during the 45-day period. Taylor said it was under evaluation.

Dan Hirsch, co-founder of Committee to Bridge the Gap, a nuclear watchdog group, which was a plaintiff in the lawsuit leading to court's decision earlier this month, was dismayed by DOE moving forward with the cleanup.

It was "breathtaking arrogance," Hirsch said. "It took intervention by legislators and the state toxics agency to stop this at the last possible moment."

U.S. District Judge Samuel Conti found the department had violated and was continuing to violate federal law the National Environmental Policy Act because it has not prepared the statement. The study would analyze the impacts of radioactive and chemical contamination and impacts associated with the cleanup activity.

On Wednesday, California's Department of Toxic Substances Control sent a strongly worded letter to the Energy Department stating it would halt its review of the site's cleanup plan because its work would be affected by the environmental study.

Norman Riley, DTSC's project director for the field lab, wrote that it was inappropriate for DOE to dismantle the two remaining facilities in the lab's nuclear research area before completing the Environmental Impact Statement.

Riley wrote that "the purpose of the EIS is to consider potential environmental impacts prior to taking actions, not afterwards."

With the letter written and ready to go, DTSC received an e-mail from Assemblywoman Julia Brownley, D-Santa Monica, who expressed shock upon learning about DOE's plans to move forward on the cleanup. Brownley demanded an explanation from DTSC about what was unfolding.

Brownley said the revelation that DOE had been continuing the cleanup "was very much to our surprise. We were sort of celebrating the court decision, then to find this out was beyond belief."

Brownley said DOE's next action should be undertaking the environmental impact statement.