Not far below the confluence with San Timoteo Creek, Lytle Creek enters from the north. Lytle Creek is one of the largest tributaries of the Santa Ana river, rising from three forks in the San Gabriel Mountains and flowing southeast, before emptying into the Santa Ana River as Lytle Creek Wash. From there, the river turns southwest, and after passing through western Riverside, it discharges into the normally dry flood control reservoir formed by Prado Dam. Two major tributaries of the river join in the reservoir area: Chino Creek from the north, and Temescal Creek from the south. Temescal Creek drains the largest area of all the tributaries, because it provides the outflow from Lake Elsinore, into which the San Jacinto River flows. It is also one of the longest, at in length. Except during the wettest years when Lake Elsinore fills high enough to overflow, Temescal Creek contributes little to no water into the Santa Ana River.