Cows feed at a Washington state dairy. The dairy industry and environmental groups have filed legal challenges to the Department of Ecology's new rules for storing and spreading manure.

OLYMPIA — The Washington Department of Ecology has proposed new rules for concentrated animal feeding operations, toughening regulations in response to a court decision.

The rules, proposed June 22, will apply to 24 operations, mostly dairies, where manure seeped into groundwater or ran into surface water. Because of the release, the farms had to get a CAFO permit.

An appeals court last year agreed with environmental groups that manure-control rules Ecology adopted in 2017 were too lax. Ecology said the court decision guided its revision.

“Large livestock operations must effectively manage their manure to protect drinking water, shellfish resources, and fish-bearing streams,” Ecology’s water quality program manager Vince McGowan said in a statement.

“We are committed to continuing to work with livestock owners and stakeholders to ensure these facilities are using best practices to prevent pollution,” he said.

The Washington State Dairy Federation said it was reviewing the rules.

A CAFO permit requires farms to follow rules for maintaining manure lagoons and testing for pollutants in fields where manure has been applied.

The permit requires farms to file plans to prevent manure pollution and mandates extensive record-keeping.

The rules are in addition to regulations enforced on all dairies by the state Department of Agriculture.

The revisions include shortening the distance between lagoons and water tables. The rules will add requirements on monitoring the condition of lagoons.

In some cases, farms will have to hold off fertilizing with manure if rain is in the forecast.

Ecology will take public comments on the proposal until Aug. 3.