[2] Historically, the interaction of the river's flow and the ocean's tide created a dynamic environment, supporting freshwater, brackish, and saltwater species.

Spread across the northernmost end of the Gulf of California, the Colorado River delta's vast riparian, freshwater, brackish, and tidal wetlands once covered 7,810 km2 (1,930,000 acres) and supported a large population of plant, bird, aquatic, and terrestrial life.

[4] Because most of the river's flow reached the delta at that time, its freshwater, silt, and nutrients helped create and sustain a complex system of estuarial wetlands that provided feeding and nesting grounds for birds, and spawning habitat for fish and marine mammals.

[5] Early explorers reported jaguars, beavers, deer, and coyotes in the delta, in addition to the abundance of waterfowl, fish, and other marine and estuary organisms (Spamer, 1990; {Aldo Leopold, 1948}).

The Cucapá used the delta floodplain extensively for harvesting Palmer's saltgrass (Distichlis palmeri), a wild grain that grows in salty soil, and for cultivating maize (corn), beans, and squash.

Decades of dam construction and water diversions in the United States and Mexico have reduced the delta to a remnant system of small wetlands and brackish mudflats.

With these reservoirs now filled, the dams are used to regulate flow so that water can be reliably apportioned among the users of the Colorado River Compact, and its use maximized.

Most flood flows can be contained, regulated, and added to the river's capacity to sustain the Western United States' urban centers and agriculture.

Floodwaters are released only when the Bureau of Reclamation, the agency managing the dams, predicts flows that exceed the system's capacity for use and storage.