The U.S. Environmental Protection Agency yesterday sued Allegheny Ludlum Corp., alleging that the steelmaker is dumping oil and wastewater into two local rivers and a third waterway in Connecticut.

The EPA is asking a federal judge to order the steelmaker to comply with the Clean Water Act. The EPA alleges that:

-- Since July of 1990, Allegheny Ludlum has dumped wastewater and effluent containing excessively high levels of nickel, copper and iron into the Kiskiminetas River from its Vandergrift plant.
-- At its plant in West Leechburg, Armstrong County, Allegheny Ludlum dumped oil into the Kiskiminetas River.
-- At its plant in Brackenridge, Allegheny Ludlum discharged dolomite into the Allegheny River on Feb. 9, 1993. On April 14, 1993, the same plant discharged oily waste, which produced a sheen on the Allegheny River. Similar oily discharges occurred on May 24 and Aug. 28, 1993.
-- Between March of 1987 and March of 1995, the company has polluted the Quinnipiac River from its Wallingford plant in Connecticut by dumping oil, grease, chromium, fluoride, iron and pickling wastewater.

The EPA is seeking civil penalties of up to $ 25,000 a day against the steelmaker for each alleged violation of the Clean Water Act.

Allegheny Ludlum spokesman Bert Delano said:

''While it's not our policy to comment on litigation, particularly that which we've not yet had an opportunity to review, we're surprised by this afternoon's allegations made by the EPA, with whom we've worked closely over the years.

''Allegheny Ludlum has spent ... more than $ 40 million in the last four years alone to maintain and operate all facilities in compliance with applicable environmental laws and regulations. This reflects our continuing pledge to our employees, to the communities where we operate and to the public.''