The Sierra Club filed suit last week in federal court in Baltimore charging three Maryland companies with polluting the Patapsco River and asking for thousands of dollars in civil penalties from them.

"Our ultimate goal here is to clean up the Chesapeake Bay and to encourage state action," said G. Macy Nelson, one of the club's Baltimore attorneys.

An attorney for the state said that in the cases of at least two of the firms, Maryland was investigating alleged pollution problems before the Sierra Club filed its notices. The state is deciding whether to take the companies to court or to enforce the Clean Water Act administratively, said Michael Powell, an assistant attorney general.

The suits allege that Simkins Industries Inc., Nueva Engineering Inc. and Keystone Automotive Plating Co. repeatedly violated the terms of their state permits allowing them to discharge certain levels of wastes into the river and requiring them to regularly monitor and report on discharges.

Daniel Morrissey, general manager of Keystone Plating, said the alleged violations stemmed solely from "problems in the way our reports were filled out." He said state and federal inspectors had found the plant in compliance with its permit.

At Nueva Engineering, operations manager John Vaughan acknowledged past pollution problems. But he said the company closed an outmoded plant in September and recently installed a $150,000 system at another plant to purify discharges.

A representative from Simkins could not be reached for comment.