In two new executive orders, Trump seeks to expand executive power over pipelines and make it harder for states to block oil and gas projects.
The proposal would endanger watersheds that sustain wildlife and supply drinking water for millions of Americans.
A new report estimates that remediating contaminated small water systems could cost up to $666 a year per person.
A federal judge issued a nationwide injunction on the Trump administration's order delaying the Clean Water Rule.
Over 12 million gallons of untreated wastewater has flowed into California from Mexico since 2015.