PORTLAND — The state’s highest court on Friday gave municipalities the green light to enact environmental regulations that are tougher than current state guidelines.

The court ruled unanimously in upholding the town of Jay’s environmental ordinance, although the court backed a reduction in fines levied against International Paper Co. for violating the ordinance.

Michael Gentile, lawyer for Jay, said the ruling is a victory for municipalities that want to tackle environmental issues on their own, rather than relying on state enforcement.

“If they want to take environmental issues into their own hands, they can do so,” Gentile said in an interview from Augusta.

IP’s Androscoggin Mill was fined $394,000 by the town’s planning board under an environmental ordinance that was enacted after an accidental discharge of chlorine at the mill in 1988.

IP contended on appeal that the fines were levied unfairly and that state law should pre-empt the local statute.

A lower court ruled that the planning board overstepped its bounds by imposing fines on 113 days when data was in question. But it upheld other violations and sent the case back to the board.

The town appealed the decision on the violations, and IP appealed the issue of which law has precedence.

The Maine Supreme Judicial Court ruled Friday that the town does have the right to impose environmental rules and penalties stricter than standards already in place under state law.

“The town’s action to enforce its ordinance by imposing penalties for violation of the ordinance is sanctioned by the Legislature,” Justice Kermit Lipez wrote in the unanimous ruling.

The court sided with International Paper on the issues of fines, ruling that the planning board relied upon data that was outside the scope of Jay’s original ordinance when it imposed penalties for 113 days.

The only method of determining compliance under the town ordinance is testing of IP’s smokestacks. The town may rewrite its ordinance to include other criteria for determining violations, the court said.

James T. Kilbreth, lawyer for IP, said the ruling was a victory because it effectively reduced the fine against the papermaker from $394,000 to a maximum of $62,000.

“We’re very pleased about that,” Kilbreth said.

The violations resulted when IP conducted tests of its compliance with town emissions levels on four days between November 1991 and June 1992. Each time, IP exceeded levels set by the ordinance.

The Jay Planning Board issued fines for each of the four days, and using other data supplied by IP, inferred that violations had occurred on 113 other days. The total fines were $394,000.

Now the case goes back to the planning board, which can levy a maximum penalty of $10,000 for each of the four days that IP smokestack emissions violated, along with $22,000 in other penalties allowed by the supreme court, Gentile said.

The board will likely revisit the ordinance to determine new methods of ensuring compliance, he said.

Kilbreth, the IP lawyer, said the company has a difference of opinion over whether both the state and the town can collect fines for violations of air quality standards.