 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.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.