Plaintiffs who have filed suit to block the implementation of new rules from the Environmental Protection Agency and the Corps of Engineers defining “waters of the United States” that can be regulated under the Clean Water Act got a big boost last week.

And it looks as though they can thank the EPA.

EPA and the Corps have been working on the rule for a couple of years now in the hopes of reconciling two separate Supreme Court decisions on cases involving the Clean Water Act.

Since the beginning, farm and ranch groups have said the new rule would expand the EPA’s authority to cover every thing up to and including muddy hoof prints.

So they and the attorneys general of several states have filed separate lawsuits to stop the implementation of the recently released draft rule.

Turns out the Army Corps of Engineers doesn’t think much of the rules, either, at least the way the EPA wrote them. In memos written by the Corps to the EPA before the rule was released, the Corps alleges:

• That in writing the rule the EPA ignored sound science, and ignored the Corps’ input to such an extent that it doesn’t consider the rule the collaboration the published draft claims to be.

• That the rule removes Clean Water Act protection from some bodies of water where it is now enforced. That’s because the rule limits coverage to lakes, ponds and other waterways that are within 4,000 feet of a navigable water or tributary. The Corps says there’s no scientific basis for the limit, and no legal authority for the agencies to abandon its current jurisdiction.

• That because the EPA acknowledged that abandoning jurisdiction could create “significant adverse effects on the human environment,” the National Environmental Policy Act requires the Corps to perform an Environmental Impact Statement.

• That while the rule envisions the agencies extending regulation to isolated bodies of water that have a “significant nexus” with navigable waters of the United States, the definitions of such bodies as having “no hydrological connection with navigable waters” makes it unlikely the agencies will be able to establish a nexus that will withstand a court challenge.

The Corps, it seems, has found that the EPA doesn’t listen to anyone and does whatever it wants. What a surprise.

It will take awhile for all this to play out in the courts, and it’s unclear what impact the Corps’ memos will have on the cases.

But it can only be a good thing for plaintiffs when one of the defendants makes their case.