Attorney General Phil Weiser has filed a lawsuit against the U.S. Environmental Protection Agency challenging a regulation that removes some water bodies from federal oversight and, according to Weiser, “ignores sound science.”

The EPA’s Navigable Waters Protection Rule, published in April, will remove federal protections from some wetlands and streams. As Weiser contends in his lawsuit, the narrowed definition of “waters of the United States” would render a “substantial portion of Colorado’s ephemeral streams and wetlands without the federal regulatory protections that the State has relied on for many years and jeopardize the integrity and quality of Colorado’s waters.”

The new rule does not include ephemeral streams that exist due to snow melt or precipitation. The Clean Water Act of 1972 makes it illegal to discharge pollutants into the waters of the United States, without defining what the phrase encompasses. Under the Obama Administration, a proposal of the rule had an expanded definition of navigable waters, on the grounds that some smaller bodies could be polluted in a way that reaches drinking water.

“The federal government’s proposed new definition of ‘waters of the United States’ conflicts with the text of the Clean Water Act, contravenes controlling Supreme Court precedent, contradicts the Act’s objective, and ignores sound science,” Weiser wrote in the lawsuit. He added that the narrowed scope of protected waters would deny the state federal resources in preventing pollution.

The Trump Administration’s rule has found some support within Colorado. U.S. Rep. Doug Lamborn explained that it “restores the federal-state partnership that Congress originally intended under the Clean Water Act and returns jurisdiction to State and local authorities, who are better able to manage their own waters.”