the summer, making irrigation difficult. The Serrano Irrigation District was formed in 1928, and partnered with the Irvine Company and the Carpenter Irrigation District of El Modena, for the construction of Santiago Dam, impounding Lake Irvine. Construction work begun in 1929 and the dam was completed in 1931. The agricultural areas in the creek's lower watershed were replaced by residential and commercial development in the Post-WWII era, but the city of Villa Park and some of the city of Orange still receive their water from Irvine Lake. Villa Park Dam The Villa Park Dam, forming the Villa Park Reservoir further downstream on Santiago Creek, was completed in 1963 also by the Serrano Irrigation District, which by that time, had changed its name to the Serrano Water District. The lower course of Santiago Creek ended up being channelized in the mid-20th century after the passage of the Orange County Flood Control Act of 1927. The dam is now owned by the Orange County Flood Control Division. Biology Historically, Santiago Creek supported a rich riparian community along its shores. The Santa Ana Mountains supported a large population of California grizzly bear, now extinct, and other large mammals such as mountain lions, bobcats, and coyotes. Today, the upper Santiago Creek remains much in its natural state, while the lower creek is listed as highly disturbed and no longer supports much native vegetation and wildlife. Historically, the creek is known to have sustained a population of steelhead trout (Oncorhynchus mykiss), but with the construction of Villa Park and Santiago Creek dams, their anadromous spawning runs from the sea have been destroyed. However, 13 specimens of the land-locked form of steelhead, rainbow trout, were fin-sampled recently from Harding Canyon and genetic analysis has shown them to be of native and not hatchery stocks. Historically, at least two tributaries to Santiago Creek, Silverado and Harding Canyons, also supported steelhead. The watershed now primarily supports introduced fish in Lake Irvine. Recreation Recreation along Santiago Creek, in its watershed, and at its reservoirs includes: Lake Irvine Lake Irvine was opened for fishing in 1941. A fishing license is not required to catch fish at the reservoir. The lake was stocked with fish in the 1930s beginning with largemouth bass, catfish, and panfish. The lake is still stocked weekly with fish. Irvine Regional Park Irvine Regional Park, created in 1897, now occupies much of the lowermost Santiago Creek Canyon,