pipeline and flume to Peters Canyon Reservoir. Because the flume diverts the creek's entire flow, the creek below the dam is dry except during floods. Below the dam the dry riverbed meets Fremont Canyon, a right bank tributary, and crosses underneath California State Route 241. It then flows northwest, bisecting Irvine Regional Park, and receives Weir Canyon Creek from the right. Near Villa Park, the Villa Park Dam forms a flood control reservoir to control spills from Irvine Lake. Below Villa Park, the creek is confined to a flood control channel for the remaining of its course. Flowing roughly southwest between the cities of Orange and Santa Ana, it receives Handy Creek from the left, then crosses under California State Route 55 and 22, through Hart Memorial Park and Santiago Creek Park. Because the creek is dry most of the year, portions of the river bed are used as parking lots when conditions permit. The creek then crosses under Interstate 5 and continues west toward the Santa Ana River. Its confluence is on the river's left bank, inside the Riverview Golf Course. About below the confluence with Santiago Creek, the Santa Ana River enters the Pacific Ocean at Huntington Beach. Watershed The Santiago Creek watershed occupies much of the northwestern end of the Santa Ana Mountains, and is located generally north of the city of Irvine. It is bounded on the south by the San Diego Creek, Aliso Creek and Oso Creek drainage areas, on the southeast by the Trabuco Creek watershed, and on the north and west by tributaries of the Santa Ana River. At in size, the Santiago Creek watershed makes up about 3.6% of the entire Santa Ana River watershed - but makes up about 65.7% of the of Santa Ana River watershed within Orange County, and 10.6% of Orange County. Most of the watershed is unincorporated, but about a third lies within Anaheim, Villa Park, Orange, and Santa Ana. Elevations in the watershed range from at Santiago Peak to at the Santa Ana River confluence. Although only tiny parts of the Santiago Creek watershed do not lie within Orange County, it closely borders Riverside and San Bernardino counties. The Santa Ana Mountains rise higher on the right bank of the creek (the north bank) than on the left (south) bank, and parts of the northernmost course of the creek run through the Puente Hills. The major