Maryland environmental officials have decided, after a review ordered by Gov. William Donald Schaefer, to stick with strict new pollution standards designed to protect the Chesapeake Bay.

Schaefer told the Department of the Environment to take another look at the new toxic discharge regulations last spring after four of Maryland's largest companies -- including Baltimore Gas and Electric -- filed suit and said the water standards were of questionable value and could cost customers billions of dollars.

Michael P. Sullivan, a department spokesman, said last week the review concluded that the standards should not be relaxed. Two weeks ago, the Environmental Protection Agency approved the state's regulations, he said.

A spokeswoman for BG&E, Peggy Mulloy, said the utility was disappointed in the department's decision. "Now there's going to be a trial, and that can be costly," Mulloy said.

The regulations, which went into effect in April, increased from seven to 27 the number of toxic chemicals -- including copper, nickel, lead and selenium -- subject to tests and limits before water from major treatment plants can be discharged into Maryland waterways.

"These are the minimum standards necessary to protect the bay," said Will Baker, president of the environmentalist Chesapeake Bay Foundation. "We were party to the negotiations developing these regulations. There was a lot of give and take, and we were worried that we gave too much."

The suit against the regulations -- filed by BG&E, Bethlehem Steel, Delmarva Power and Light and Baltimore Specialty Steel -- is in Baltimore Circuit Court. The court is considering whether the state acted within its authority to adopt the regulations.

The companies claim that the pollution standards for plant discharges are, in some respects, more strict than the regulations that apply to drinking water.

New treatment facilities would cost huge sums, they said, contending that the state had exceeded the standards suggested by the EPA.

"All the money we would have to pour into {meeting the standards} wouldn't lower limits of the toxics significantly," Mulloy said.

The new regulations are applicable upon the expiration of five-year permits held by companies and municipal waste treatment plants, Sullivan said.

While the suit is pending, putting the future of the regulations in doubt, old permits are being extended in many cases, he said.