On October 19, 2018, the Trump administration issued Memorandum 2018-23519 directing federal agencies to prioritize what it termed reliable water supply and delivery in western states. The directive instructed the Department of Interior and related agencies to review and modify existing federal water management policies and regulations governing operations of major federal water projects. Rather than rely on formal rulemaking processes that typically involve public comment periods, the administration used the memorandum mechanism to expedite policy changes affecting water allocations across the Colorado River Basin, Central Valley Project, and other critical infrastructure systems that supply irrigation, hydropower, and municipal water to millions of Americans.

The practical consequences fell directly on agricultural irrigators, municipal water districts, hydropower producers, and environmental interests relying on managed river flows. Farmers dependent on federal irrigation deliveries saw prioritization shifts toward maximizing surface water deliveries over environmental flow requirements. Hydroelectric facilities operated by the Bureau of Reclamation faced operational constraints changes. Communities in California, Nevada, Arizona, Utah, and other western states experienced altered water availability as federal project operations adjusted to reflect the administration's emphasis on supply maximization over conservation management and ecosystem protection.

This memorandum fit within a broader pattern of environmental deregulation that intensified substantially in later years. The approach—using executive directives to bypass standard regulatory procedures—prefigured later actions including the EPA leadership overhauls and regulatory rescissions under Trump's second term that systematically dismantled environmental protections. The water memorandum specifically anticipated the administration's later invocation of the Defense Production Act for fossil fuel acceleration, sharing the same philosophy of using federal authority to prioritize resource extraction and industrial production over environmental safeguards. Both reflected a fundamental reorientation of federal agencies away from conservation and toward what the administration characterized as economic productivity.

Reversing these changes would require either a new presidential memorandum or congressional legislation restoring the prior regulatory frameworks governing federal water project operations, reimposing environmental flow requirements and conservation-focused operational guidelines that had governed these systems for decades.