MADISON, Wis. — Republican Attorney General Brad Schimel has settled a pollution case with 3M that won’t require the company to pay any fines, which critics said will only encourage companies to ignore environmental regulations.

Schimel spokesman Johnny Koremenos the Justice Department is proud of the settlement, which was reached in November.

As first reported by the Milwaukee Journal Sentinel, the agreement requires 3M Co. to spend an estimated $665,000 by August 2018 on improvements to pollution control equipment that failed repeatedly at two plants in Wausau.

Top environmental regulators said they aren’t aware of any case in the last 25 years in which a state attorney general took a polluter to court without winning a penalty.

“This doesn’t provide effective deterrence for the companies that want to cut corners on pollution controls,” said George Meyer, who formerly led the Department of Natural Resource’s enforcement division.

Koremenos said the expenditures 3M has agreed to are a “supplemental environmental project.” Under federal rules, such projects are supposed to reduce penalties while producing environmental benefits beyond the requirements for a defendant’s compliance with the law.

The $665,000 is greater than the cost for the company to bring its facilities into compliance with the law, Koremenos said. He declined to say how much money was spent on meeting legal requirements and how much covered additional improvements.

Schimel appeared before the Legislature’s Joint Finance Committee on Wednesday to answer questions about the state Department of Justice’s portion of Gov. Scott Walker’s proposed 2017-19 budget. The committee’s four Democratic members grilled him about a variety of issues, including the settlement.

Rep. Katrina Shankland, of Stevens Point, took Schimel to task for not slapping polluters with more fines, saying she was concerned about the precedent the settlement set.

Schimel said he wants to fix problems rather than impose fines.

“We leveraged concessions out of them we wouldn’t have gotten if we’d just gone forward and gotten a forfeiture,” he said.

3M spokeswoman Fanna Haile-Selassie said in a statement that the company made repairs, maintenance and upgrades to equipment after the natural resources department cited pollution violations. She did not provide a dollar figure. She said the company is constantly improving its operations.

Meyer said the company should have begun fixing its problems as soon as it became aware of them in 2014 or earlier.

The project includes adding electronic equipment that is supposed alert employees when pollution control machinery stops working, as well as the company’s continued participation in a private environmental improvement program called ISO 14001, which it has been enrolled in since 2010.