miscellaneous (4.9 percent), agriculture (3.7 percent) and industrial (1.6 percent). Public lands, including national forest and county parks, comprised 26.4 percent of the watershed, and another 13.1 percent was unincorporated. Much of the terrain in the watershed has been regraded to build homes and roads, and a number of smaller tributaries such as Munger Creek have been completely filled in. Crossings Crossings of the creek are listed from mouth to source (year built in parentheses). The creek is crossed by roughly 30 major bridges. Six footbridges in the Aliso Creek Golf Course SOCWA Coastal Treatment Plant access road Service Road for ACWHEP Dam AWMA (Aliso Water Management Agency) Road Aliso Creek Road (1988) Pacific Park Drive Aliso Creek Trail Moulton Parkway (northbound 1969, southbound 1987) Laguna Hills Drive—twin bridges (1985) Avenida Sevilla Two footbridges in Aliso Park Paseo de Valencia (1966) Aliso Creek Trail Aliso Creek Trail Los Alisos Boulevard (1973) Muirlands Boulevard (1973) Private road in Lake Forest Golf Center Surf Line Jeronimo Road (1974) Aliso Creek Trail/2nd Street pedestrian bridge Aliso Creek Trail Trabuco Road—twin bridges (1975) Creekside Drive (1980) El Toro Road (1975) Normandale Drive (1987) Portola Parkway Saddleback Parkway Aliso Creek Trail Aliso Creek Trail Glenn Ranch Road Aliso Creek Trail El Toro Road El Toro Road Santiago Canyon Road Crystal Canyon Road Country Home Road Tributaries From mouth to source, Aliso Creek is joined by seven major tributaries. Another forty-six minor streams and drains flow into the creek. Geology Most of Southern California, including all of Orange County, was part of the Pacific Ocean until about 10 million years ago (MYA) when regional uplift began. The Santa Ana Mountains, where the creek originates, began to rise about 5.5 million years ago along the Elsinore Fault. Most of the Aliso Creek watershed sits on several layers of marine sedimentary strata, the oldest dating from the Eocene (55.8–33.9 MYA) and the most recent, the Pliocene (5.33–2.59 MYA). These alluvial sediments range from in depth. The watershed includes outcrops of the Topanga Formation, Monterey Formation, San Onofre Breccia, Capistrano Formation and Niguel Formation. Generally throughout the watershed, there are five major soil and rock outcrop types—Capistrano sandy loam, Cieneba sandy loam, Marina loamy sand, Myford sandy loam, and Cieneba-rock outcrop. The water table ranges from deep. About 1.22 million years ago, the San Joaquin Hills along the Orange County coast began their uplift along the San Joaquin Hills