Washington ? The Bush administration plans to require the nation’s 15,000 chemical, water and waste-treatment plants to assess how vulnerable they are to terrorists and then fix any problems, The Associated Press has learned.

The terrorism assessments would be similar to risk management plans the Environmental Protection Agency already requires from the same facilities for accidental releases of toxins, a senior EPA official said Friday.

An interagency group led by the White House’s Office of Homeland Security has been developing the plan, and EPA Administrator Christie Whitman is expected to announce it within days, the official said, speaking on condition of anonymity.

Principles for the terrorism assessments and subsequent fixes were modeled after guidelines crafted by a trade group, the American Chemistry Council, for its 180 corporate members who operate about 1,000 of the affected plants, the official said.

EPA has not yet determined whether new legislation is needed from Congress or whether the agency can order the measures on its own, the official said.

The Justice Department and the Energy Department’s Sandia National Laboratory have been working together to develop methods for assessing a chemical plant’s vulnerability to terrorists. A similar effort also is under way by the American Institute of Chemical Engineers’ Center for Chemical Process Safety.

EPA already has taken steps to reduce chemical plants’ risks of becoming terrorist targets. Soon after the Sept. 11 attacks on the World Trade Center and the Pentagon, it removed from its Web sites the risk management plans for spills and airborne releases of toxins.

Publishing those plans had been required under the belief that neighbors of a chemical plant had a right to know the risks to which they were being exposed. However, the industry and U.S. intelligence agencies have complained for years that publishing the data created a roadmap for terrorists.

The envisioned EPA orders for chemical, water and waste-treatment plants will cover site and computer security; access; background checks for employees, vendors and customers; inventory controls, storage practices and the availability of safer manufacturing and treatment technologies. EPA would have to certify the completion and thoroughness of the assessment for each of the 15,000 plants.