A Trump administration memo calls on the Secretary of Commerce and the Secretary of the Interior to develop a new plan within 90 days “to route more water from the Sacramento-San Joaquin Delta to other parts of the state for use by the people there who desperately need a reliable water supply.

It’s one of California’s thorniest problems. The nation’s most populous state is full of sprawling cities, vast farmland, rich ecosystems — and it must decide how to divide scarce water resources among them.

U.S. President Donald Trump said on Tuesday he will issue an executive order to increase the availability of water in California, following disastrous wildfires that recently tore through several Los Angeles neighborhoods.