Wasley responded to the “arbitrary” charge by saying the rule is a “general protection strategy” for waterways and is very similar to a Wisconsin provision.

Currently, it’s difficult to put a limit on a facility because there needs to be proof that facilities phosphorus discharge had a big impact on a downstream body of water.

There is a solution to the impasse: The rule has a number of “offramps,” or exceptions.

Sullivan, the coalition lawyer, said if those offramps give cities enough flexibility, it would abandon the lawsuit.

The offramps include an exception to the rule in cases where it would do more environmental harm than good. That could happen if facilities are forced to dump more phosphorus sludge on land.