Dozens of advocacy groups have filed a lawsuit against the Environmental Protection Agency (EPA), claiming the federal department has failed to come up with a plan to regulate water pollution from factory farms.

The suit claims the agency has yet to respond to a 2017 legal petition from more than 30 environmental groups demanding that the EPA tighten its Clean Water Act enforcement for factory farms, also known as concentrated animal feeding operations (Cafos), where thousands of animals are sometimes confined.

The agency has never explained how it plans to crack down on water pollution that often contains manure, antibiotics and chemicals, the groups argue. Federal rules require government agencies to respond to petitions “within a reasonable time”.