Trampas Canyon is a short tributary of

San Juan Creek San Juan Creek, also called the San Juan River, is a long stream in Orange and Riverside Counties, draining a watershed of .7.5 Minute Quadrangle Map, U.S. Geological Survey, San Juan Capistrano, 1968, photorevised 1981 Its mainstem begins in ...

in southern

Orange County Orange County most commonly refers to: *Orange County, California, part of the Los Angeles metropolitan area Orange County may also refer to: U.S. counties *Orange County, Florida, containing Orlando *Orange County, Indiana *Orange County, New ...

the

U.S. state In the United States, a state is a constituent political entity, of which there are 50. Bound together in a political union, each state holds governmental jurisdiction over a separate and defined geographic territory where it shares its sover ...

California California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...

. It rises in forks on steep slopes of the southern

Santa Ana Mountains The Santa Ana Mountains are a short peninsular mountain range along the coast of Southern California in the United States. They extend for approximately southeast of the Los Angeles Basin largely along the border between Orange and Riverside co ...

(), and flows north to where it is dammed by Trampas Canyon Dam (USGS San Clemente Quad 7½"). Trampas Canyon 1795-006 Dam () forms a small lake that branches into four forks running east–west. Exiting the dam, the creek flows north and turns slightly to the west, where it joins San Juan Creek on the left bank, near the confluence of

Cañada Gobernadora Cañada Gobernadora is a tributary to San Juan Creek, about long, in southern Orange County in the U.S. state of California. The creek begins in the foothills of the Santa Ana Mountains (), at an elevation of , and flows south through residential ...

(). Trampas Canyon Creek is

ephemeral Ephemerality (from the Greek word , meaning 'lasting only one day') is the concept of things being transitory, existing only briefly. Academically, the term ephemeral constitutionally describes a diverse assortment of things and experiences, fr ...

and only flows during storm events or while Trampas Canyon Dam is releasing, and is not a primary tributary of San Juan Creek. A study was prepared in 1999 by the City of

San Juan Capistrano San Juan Capistrano (Spanish for "St. John of Capistrano") is a city in Orange County, California, located along the Orange Coast. The population was 34,593 at the 2010 census. San Juan Capistrano was founded by the Spanish in 1776, when St. ...

, and it was found that a failure of the earthen Trampas Canyon Dam would do more damage to the lower course of San Juan Creek than for a

100 year flood A 100-year flood is a flood event that has a 1 in 100 chance (1% probability) of being equaled or exceeded in any given year. The 100-year flood is also referred to as the 1% flood, since its annual exceedance probability is 1%.Holmes, R.R., Jr. ...

. A failure would cause a floodwave over wide to rush down the lower of San Juan Creek to

Doheny State Beach Doheny State Beach is a protected beach in the state park system of California, United States, located on the Pacific Ocean in the city of Dana Point. The beach is a popular surf spot located at the mouth of San Juan Creek, which flows from th ...

, flooding parts of San Juan Capistrano and

Dana Point Dana Point () is a city located in southern Orange County, California, United States. The population was 33,107 at the 2020 census. It has one of the few harbors along the Orange County coast, and with ready access via State Route 1, it is a po ...

. A 100-year flood would cause a slightly smaller inundation.Technical Background Report, General Plan Update - City of San Juan Capistrano, August 1999

References

External links

Orange County Watersheds: San Juan Creek
{{Orange County major watersheds Rivers of Orange County, California San Juan Creek Rivers of Southern California