El Horno Creek or Horno Creek (Spanish

Spanish language

Spanish , also known as Castilian , is a Romance language in the Ibero-Romance group that evolved from several languages and dialects in central-northern Iberia around the 9th century and gradually spread with the expansion of the Kingdom of Castile into central and southern Iberia during the...

: "Oven Creek") is a tributary

Tributary

A tributary or affluent is a stream or river that flows into a main stem river or a lake. A tributary does not flow directly into a sea or ocean...

 stream of San Juan Creek

San Juan Creek

San Juan Creek, also called the San Juan River, is a stream in Orange County, California that consists of a catchment basin encompassing . Its mainstem rises in the Santa Ana Mountains, in the Trabuco Ranger District of the Cleveland National Forest...

 in Orange County

Orange County, California

Orange County is a county in the U.S. state of California. Its county seat is Santa Ana. As of the 2010 census, its population was 3,010,232, up from 2,846,293 at the 2000 census, making it the third most populous county in California, behind Los Angeles County and San Diego County...

 in the U.S. state

U.S. state

A U.S. state is any one of the 50 federated states of the United States of America that share sovereignty with the federal government. Because of this shared sovereignty, an American is a citizen both of the federal entity and of his or her state of domicile. Four states use the official title of...

 of California

California

California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

. It is approximately 5.9 miles (9.5 km) long and drains an area of 4.3 mi2. The creek joins San Juan Creek on the right bank, only a few hundred yards upstream of the Trabuco Creek

Trabuco Creek

Trabuco Creek is a small river in the U.S. state of California, flowing from the westernmost extreme of Riverside County through Orange County to join San Juan Creek in the city of San Juan Capistrano. long, its watershed covers in southeastern Orange County, including portions of three...

 confluence, within the city limits of San Juan Capistrano. The creek begins in the foothills

Foothills

Foothills are geographically defined as gradual increases in elevation at the base of a mountain range. They are a transition zone between plains and low relief hills to the adjacent topographically high mountains.-Examples:...

 of the Santa Ana Mountains

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 36 mi southeast of the Los Angeles Basin largely along the border between Orange and Riverside counties.- Geography :The range starts in the...

 (33.5672464°N 117.6300495°W), a mountain range that occupies most of the west half of the San Juan watershed. There is a significant amount of single-family residential development there, and the creek is mostly inside an underground storm channel. It flows south and southwest before turning west under Interstate 5

Interstate 5

Interstate 5 is the main Interstate Highway on the West Coast of the United States, running largely parallel to the Pacific Ocean coastline from Canada to Mexico . It serves some of the largest cities on the U.S...

, where it enters a channelized course and parallels the interstate to its discharge point at San Juan Creek, also from a subterranean culvert

Culvert

A culvert is a device used to channel water. It may be used to allow water to pass underneath a road, railway, or embankment. Culverts can be made of many different materials; steel, polyvinyl chloride and concrete are the most common...

 (33.4978044°N 117.6553283°W). Although significant stretches of the creek remain above ground, riparian habitat along the creek remains "sporadic" despite its perennial flow mainly due to pollution from stormwater.