A group of ranchers sued the Trump administration Monday over a rollback to an Obama-era water rule they argue is still too strict.

At stake is the Navigable Waters Protection Rule, a rule President Trump Donald John TrumpOmar fires back at Trump over rally remarks: 'This is my country' Pelosi: Trump hurrying to fill SCOTUS seat so he can repeal ObamaCare Trump mocks Biden appearance, mask use ahead of first debate MORE repeatedly promised to deliver for farmers who complained previous policy left huge swatches of their land subject to federal oversight.

But the suit from the New Mexico Cattlemen’s Association argues the latest Trump replacement is both too strict, violating “the Constitution, the Clean Water Act, and Supreme Court precedent,” and lacks key definitions.

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“The act does not define ‘navigable,’” they argued, leaving it unclear whether it falls to the Environmental Protection Agency (EPA), the Army Corps of Engineers or the state to regulate various water bodies.

But they said the rule “provides no guidance or criteria to the agencies” to sort out who will oversee what.

Environmental groups, who have likewise pledged to sue over the rule, see it differently.

“This is not just undoing the clean water rule promulgated by the Obama administration. This is going back to the lowest level of protection we’ve seen in the last 50 years,” Collin O’Mara, president and CEO of the National Wildlife Federation, said when the rule was announced in January. “This is a staggering rollback.”

President Obama’s Waters of the U.S. rule was also heavily litigated, particularly by farmers who said it was too far reaching.

Repealing that water rule was a campaign promise of Trump's.

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“As long as I’m president, government will never micromanage America’s farmers,” he told the audience at the American Farm Bureau Federation annual meeting just days before his replacement rule was announced.

EPA said it would not comment on the pending litigation.

The challenges to the Navigable Waters Protection Rule is likely to once again put the Trump administration between environmentalists and those who were hoping for laxer regulation.

Suits filed last week against the Affordable Clean Energy rule, which weakens power plant regulations, has spurred suits from green groups as well as coal companies who argued the EPA should not have issued the new regulation at all.