Pool Schedule & Seasonal Drawdown Checker

Understanding Reservoir Rule Curves

A "rule curve" or "guide curve" is an official target water elevation schedule developed by reservoir engineers to balance multiple competing mandates: flood risk management, hydropower generation, municipal drinking water supply, downstream navigation, and recreational boating.

In regions with heavy winter snowfall or spring rainfall, the U.S. Army Corps of Engineers deliberately lowers the reservoir several feet starting in late August or September. This drawdown creates a hollowed-out storage buffer. When torrential winter storms sweep through the watershed, the dam can store millions of gallons of excess runoff without overtopping the spillway, preventing disastrous flooding in downstream towns and cities.