The effects of 14 major dams and hundreds of water diversions have been felt all the way to the river mouth. Since completion of the Glen Canyon Dam in 1963, measurable flows from the Colorado River into the Sea of Cortez have occurred only infrequently. The wetland area at the mouth of the river has decreased from a historical average of 250,000 hectares to 5,800 to 63,000 hectares (depending on the year). In the Sea of Cortez, the lack of freshwater inflows has contributed to the endangerment of a large number of species, and the loss of algal productivity has caused
the abundance of bivalve mollusk populations to drop 94 percent from 1950 values.