"Lake Perris is an artificial lake completed in 1973.It is the southern terminus of the California State Water Project, situated in a mountain-rimmed valley between Moreno Valley and Perris, California. In 2005, the water in Lake Perris was
drawn down by about 20 percent (about 24 feet) due to safety concerns
with the dam. An extensive modern study concluded that the dam could be partially breached if a 7.5 magnitude or higher earthquake were to strike in the area. Heightening the engineers' fears was the fact that the San Jacinto Fault, easily capable of creating a 7.5 tremor, passes just a few miles north of the lake. It may take two years or more for the state to plan a course of action and bolster the dam."