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San Juan Creek, also called the San Juan River, is a stream in Orange County, California that consists of a catchment basin encompassing .〔7.5 Minute Quadrangle Map, U.S. Geological Survey, San Juan Capistrano, 1968, photorevised 1981〕 Its mainstem rises in the Santa Ana Mountains, in the Trabuco Ranger District of the Cleveland National Forest. From there it runs parallel to the Ortega Highway as it winds west and south through San Juan Canyon, where it is joined by numerous small tributaries, and is joined by Trabuco Creek, its main branch as it passes through San Juan Capistrano. It flows into the Pacific Ocean at Doheny State Beach. Once out of the foothills, San Juan Creek flows through the city of San Juan Capistrano where groundwater flow direction generally is from the northeast to the southwest. Groundwater in this basin at the San Juan Capistrano reach is considered good.〔Earth Metrics Incorporated, ''Phase I Environmental Site Assessment for Rancho San Juan Capistrano, bounded by San Juan Creek Road, Paseo Ranchero and Camino San Jose Road, San Juan Capistrano, California'', January 4, 1990〕 Recent efforts of stream conservation have been in the planning stage including habitat conservation plan work.〔U. S. Army Corps of Engineers, Jae Chung, ''San Juan Creek/San Mateo Creek SAMP'', 27 December 2007〕 Historically, the San Juan Creek watershed was inhabited by the Acjachemen, now Juañeno Indians. The Juañeno received their current name from Spanish conquistadors in the 1770s, who built Mission San Juan Capistrano very near San Juan Creek, giving it its name. After the Spanish settlement, development in the watershed continued to grow and pollution of the creek has increased. The construction of Dana Point Harbor in 1960 increased the pollution of San Juan Creek at its mouth, posing an increasing danger to visitors of Doheny State Beach. In the late 1990s and early 21st century, floods destroyed many river control structures in the San Juan watershed, and the risk of floods continues to grow. Although the San Juan watershed was formerly rich in biodiversity, with sixteen major plant communities and hundreds of species of birds, invertebrates, mammals, and others, the watershed is projected to be 48 percent developed by the year 2050. Many reaches of open land in the San Juan watershed are now heavily developed, and urban runoff coming from residential communities is taking an increased toll on the creek and its tributaries. Although the mainstem San Juan Creek does not have any major water diversions or dams, its tributaries are heavily affected, most notably Trabuco and Oso Creeks. ==Course== (詳細はSanta Ana Mountains southwest of Lake Elsinore, at the head of the steep and narrow San Juan Canyon, at roughly in elevation where Morrell Canyon Creek, draining the western Elsinore Mountains and southernmost Santa Ana Mountains, has its confluence with Bear Canyon Creek. From there, it flows steeply downhill over riffles and waterfalls, and paralleling California State Route 74, here known as the Ortega Highway, as it winds through the rocky gorge. It drops over San Juan Falls, a cascade,〔Shaffer, p. 379-380〕 then crosses under an arch bridge that carries the Ortega Highway. It is joined by Hot Springs Creek and Cold Springs Creek on the right bank, while Lucas Canyon Creek meets it on the left.〔 〕 Once out of the mountains, San Juan Creek proceeds to meander through a broad and shallow farming and ranching〔 〕 valley underlain by thick alluvial deposits. The creek swings west to receive Bell Canyon on the right, from several residential communities that overlook, but do not border, it.〔 and Verdugo Canyon Creek from the left. Trampas Canyon enters from the left and Cañada Gobernadora and Cañada Chiquita enter from the right. The creek then crosses under Interstate 5, and enters a flood control channel, turning south and receiving El Horno Creek on the right. It receives its largest tributary, Trabuco Creek, on the right bank, then continues south and east to the Pacific Ocean. Before it reaches the sea, however, it enters a lagoon at the northern end of Doheny State Beach, which occasionally spills into Capistrano Bay.〔〔〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「San Juan Creek」の詳細全文を読む スポンサード リンク
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