The White House threatened to veto legislation on Wednesday that would curtail federal rules limiting the amount of water pumped out of California's San Joaquin-Sacramento River delta while the state struggles with its worst drought in decades.
The Obama administration said the bill would "undermine years of collaboration between local, state, and federal stakeholders to develop a sound water quality control plan for the Bay-Delta."
The House of Representatives is expected to vote on the Republican-backed water bill later on Wednesday.
A record-breaking dry spell has led to a water crisis that could further endanger California's Central Valley agriculture hub.
Supporters of the bill have argued that it would help provide relief by allowing state and federal water managers to deliver water to farmers and communities during dry years.
The White House said in a statement that it "strongly opposes" the bill. "H.R. 3964 would repeal the San Joaquin River Settlement Agreement, which the Congress enacted to resolve 18 years of contentious litigation. Full repeal of the settlement agreement would likely result in the resumption of costly litigation, creating an uncertain future for river restoration and water delivery operations for water users on the San Joaquin River."