Attorney General Bob Ferguson recently filed a lawsuit to block the Environmental Protection Agency’s attempt to repeal a 2015 rule that defines what waters qualify for federal Clean Water Act protections and replace that rule with a previously established rule from 1986.

Were the EPA to repeal this rule, it would significantly reduce the number of water bodies around the United States that are protected under the Clean Water Act.

The 2015 Clean Water Rule’s definition of “waters of the United States” was adopted after an extended rulemaking process. Before the rule, a patchwork of state and federal rules regulated runoff from some upstream bodies, which made pollution difficult to control.

This rule impacts states like Washington that have waterways impacted by upstream sources in neighboring states.

“The Trump Administration continues to assault sound, scientifically supported environmental policy,” Ferguson said of the filing. “Clean water is essential to our environment and our economy in the Pacific Northwest. From salmon to orcas, fishermen to farmers, clean water is the basis for a healthy Washington. We plan to stop this administration’s unlawful attempt to upend years of extensive scientific study and public input simply because it doesn’t like the result.”

The suit accuses the EPA of violating the Administrative Procedure Act and the Clean Water Act with its new rule by failing to provide a reasoned explanation for its decision and failing to provide a meaningful opportunity for public input.

After its adoption, the 2015 rule was challenged in federal court by then-Oklahoma Attorney General Scott Pruitt, former the head of the EPA under President Trump. AG Ferguson and several other states’ AG’s intervened in the suit to defend the rule.

After becoming the EPA administrator under President Donald Trump, Pruitt proposed the suspension and repeal of the 2015 rule. In 2018, Ferguson and 10 other AG’s challenged the suspension of the 2015 rule. Judges in other, similar cases blocked the administration from suspending the rule before a ruling could be issued in Ferguson’s case. Pruitt has since left the administration, but the EPA’s efforts to repeal the rule have continued.

In October, the EPA and the U.S. Army Corps of Engineers published a rule repealing the 2015 Clean Water Rule, replacing it with the rule promoted by the Army Corps of Engineers in 1986 and became effective on Dec. 23, 2019.

Ferguson is asking the court to vacate the repeal and replacement rule with senior counsel Ronald Lavigne leading the case for Washington state.