Long before the highly toxic pesticide Kepone ruined the Hopewell, Va., sewage plant, state and local officials were planning a new treatment facility there - a plant so sophisticated that environmental agencies were assured that the James River would be safe from Hopewell's chemical industry.

Last month Gov. John N. Dalton led a host of officials in dedicating the new plan as "a prime example" of how cooperative efforts could solve pollution problems.

Yet, state records show that the modern, $48 million plant consistently has been violating pollution regulations since it was opened in August 1977. Last January and February water being discharged by the plant was actually dirtier than the waste water entering the plant, state water officials said.

The State Water Control Board, adopting what a former chairman of the board claims is a new, relaxed standard toward water pollution refused to accept a staff recommendation that it sue Hopewell.

The Hopewell situation claims Noman M. Cole Jr. of Fairfax County who ran the board during a period of stringent regulation in the early 1970s, is "part of a pattern" of lax enforcement that is dirtying the state's waters.

Typical of the board's new attitude, Cole has charged, is what happened to the Loudoun County town of Leesburg, where a sewage plant was allowed to discharge excessive amounts of pollutants for five months. He also cited Stafford County, which had a polluting treatment plant that the board refused to move against.

Leesburg, Cole claims has a friend on the water board. Leesburg Mayor Kenneth B. Rollins. The mayor has been allowed to remain on the water board although state law prohibits officials of localities with sewage plants from being named to the board.

Cole, a Washington nuclear power expert who has remained interested in Virginia's water consultant to Dalton in his campaign last year is not alone in his concern.The executive director of a Virginia environment fund created after the Kepone disaster complained to Dalton this week about the Hopewell plant.

Rollins said yesterday "it was completely untrue" that the water control board was bowing to local pressure. He said neither the Hopewell nor the Stafford case has been dismissed by the board.

"Both are on the December calendar of the board," he said. As for the Leesburg violations, he said they were the result of "a new employe who turned a valve the wrong way."

"You've got to be reasonable," Rollins said. "You can't crack down and say no more sewage. You have to look at the economics, you have to look at a lot of things.

Rollins also said he saw no conflict of interest in his continuing to serve on the water control board while he was mayor of Leesburg. He said an opinion by state Attorney General J. Marshall Coleman said there was no conflict because he was not mayor of the town when when he was appointed to the board.

Federal officials, said they were troubled by the state's policy in the Hopewell case. U.S. Attorney WIlliam B. Cummings, who prosecuted the massive criminal case growing out of the Kepone pollution, yesterday called the Hopewell pollution "an abomination." Cummings said he was speaking not as a prosecutor, but as the chairman of a multimillion dollar environmental fund created by Allied Chemical Corp., one of the Kepone polluters.

The enforcement chief for the U.S. Environmental Protection Agency's regional headquarters. Stanley L. Laskowski, said this week "We are not satisfied with the (water control) board's action" in the Hopewell case.

"We're now evaluating where we can go from here," he said. We could let the state take the lead. If we are not satisfied, we could bring our own enforcement action by referring the case to the Justice Department."

EPA did not intervene earlier "because we have had to give priority to another, more important problem - industrial discharges." While about 85 percent of the Hopewell plant's sewage comes from nearby industries, Laskowski said EPA considers the Hopewell plant in a separate category because it was federally funded - and is not ranked as a high-priority industrial discharger.

Hopewell officials acknowledge that their plant was not meeting pollution requirements for the first year of its operation, but they say that there have been major improvements.

Engineers said the discharge coming from the Hopewell plant has been more contaminated than the waste water entering the plant because the plant itself has been working improperly and adding excessive quantities of chemicals to the water.

City Manager Clinton Strong said that during September the plant generally met the limitation on suspended solids and "our removal of BO (pollutants that rob water of its oxygen) was the bets we've ever had."

Strong added that "I wouldn't predict when we will be able to meet the BOD limitation." The limitation is 30 parts per million.

After hitting levels as high as 405 parts per million earlier this year, the plant last month was able to reduce BOD (pollutants that rob water of its lion," according to Strong.

Under Cole, the Water Control Board had a reputation for aggressively pursuing polluters. The board sued Fairfax County in the early 1970s in a move that forced the county to temporarily upgrade existing treatment plants until new, improved ones were on line.

Cole said localities, backed by the Virginia Municipal League, continually have sought to water down standards. "We had to fight them off all the time - nobody likes a cop," he said.