San Luis Rey River
Encyclopedia
The San Luis Rey River is a river
in northern San Diego County, California
. The river's headwaters are in the Cleveland National Forest
near Palomar Mountain
. The river drains into the Pacific Ocean
on the northern end of the city of Oceanside
. The river is over 69 miles (111 km) long and drains 562 square miles (1,455.6 km²). There is little water in the river during most of the year, but it can have very large flows during winter storms. The dam that forms Lake Henshaw
is the only one on the river itself, but the river's drainage is extensively dammed. During the last 7 miles (11.3 km), the river flows through a 400 feet (121.9 m) earthen channel with levee
s on each side to prevent flooding, although the rest of the river remains unchannelized. Urbanization, mining and agriculture have caused substantial deterioration of the watershed
. Lake Henshaw, relatively close to the headwaters, is a source of drinking water
. However, the water in the lower part of the river is only used for groundwater
recharge. In 2009, a bridge was completed across the river near its mouth, replacing a small causeway that used to wash away every few years. Along the final 9 miles, the San Luis Rey River bike path
follows it.
and flows generally south-southwest. The West Fork's headwaters rise as a pair of tiny streams, Fry Creek and Iron Springs Creek, just to the north of Palomar Mountain
. These two streams combine into the West Fork, which flows southeast through the Mendenhall Valley. The West Fork joins the main stem at Lake Henshaw
, a reservoir formed by a dam across the main stem San Luis Rey River.
From the base of Henshaw Dam, the river winds west along the foot of the Palomars, followed by California State Route 76
. It then bends southwest into a gorge. It leaves the canyon at the wide and spacious Pauma Valley, where it becomes a wash surrounded on both sides by agricultural fields. Potrero and Pauma Creeks enter from the right, then Frey Creek and Agua Tibia Creek as the river travels northwest. The river turns west, passing Pala
, flowing through a patchwork of privately owned, government-owned and Native American lands. It then crosses under Interstate 15
and exits the foothills of the mountains near Bonsall
.
After passing Bonsall the river flows generally southwest, through the cities of San Luis Rey
and Oceanside
. Although usually dry up to this point the river starts to contain water as it nears the mouth, both from seeps and from tidal activity that forms a lagoon
at the mouth of the river. The San Luis Rey empties into the Pacific north of Oceanside, about 2 miles (3.2 km) south of the Santa Margarita River
and ~30 miles (48.3 km) north of San Diego.
River
A river is a natural watercourse, usually freshwater, flowing towards an ocean, a lake, a sea, or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be called by several other names, including...
in northern San Diego County, California
San Diego County, California
San Diego County is a large county located in the southwestern corner of the US state of California. Hence, San Diego County is also located in the southwestern corner of the 48 contiguous United States. Its county seat and largest city is San Diego. Its population was about 2,813,835 in the 2000...
. The river's headwaters are in the Cleveland National Forest
Cleveland National Forest
Cleveland National Forest encompasses 460,000 acres , mostly of chaparral, with a few riparian areas. A warm dry mediterranean climate prevails over the Forest. It is the southernmost National forest of California. It is administered by the United States Forest Service, a government agency within...
near Palomar Mountain
Palomar Mountain
Palomar Mountain is a mountain in the Peninsular Ranges in northern San Diego County. It is famous as the location of the Palomar Observatory and Hale Telescope, and known for the Palomar Mountain State Park.-History:...
. The river drains into the Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
on the northern end of the city of Oceanside
Oceanside, California
-2010:The 2010 United States Census reported that Oceanside had a population of 167,086. The population density was 3,961.8 people per square mile...
. The river is over 69 miles (111 km) long and drains 562 square miles (1,455.6 km²). There is little water in the river during most of the year, but it can have very large flows during winter storms. The dam that forms Lake Henshaw
Lake Henshaw
Lake Henshaw is a Reservoir in San Diego County, Californiaat the southeast base of Palomar Mountain, approximately miles northeast of San Diego, California and miles southeast of Los Angeles....
is the only one on the river itself, but the river's drainage is extensively dammed. During the last 7 miles (11.3 km), the river flows through a 400 feet (121.9 m) earthen channel with levee
Levee
A levee, levée, dike , embankment, floodbank or stopbank is an elongated naturally occurring ridge or artificially constructed fill or wall, which regulates water levels...
s on each side to prevent flooding, although the rest of the river remains unchannelized. Urbanization, mining and agriculture have caused substantial deterioration of the watershed
Drainage basin
A drainage basin is an extent or an area of land where surface water from rain and melting snow or ice converges to a single point, usually the exit of the basin, where the waters join another waterbody, such as a river, lake, reservoir, estuary, wetland, sea, or ocean...
. Lake Henshaw, relatively close to the headwaters, is a source of drinking water
Drinking water
Drinking water or potable water is water pure enough to be consumed or used with low risk of immediate or long term harm. In most developed countries, the water supplied to households, commerce and industry is all of drinking water standard, even though only a very small proportion is actually...
. However, the water in the lower part of the river is only used for groundwater
Groundwater
Groundwater is water located beneath the ground surface in soil pore spaces and in the fractures of rock formations. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in rock...
recharge. In 2009, a bridge was completed across the river near its mouth, replacing a small causeway that used to wash away every few years. Along the final 9 miles, the San Luis Rey River bike path
San Luis Rey River bike path
The San Luis Rey River bike path is an easy, 9-mile paved class one bicycle and pedestrian trail that follows the San Luis Rey River in Oceanside, California...
follows it.
Course
The San Luis Rey River rises in two main branches. The mainstem starts east of Rocky Mountain in the Cleveland National ForestCleveland National Forest
Cleveland National Forest encompasses 460,000 acres , mostly of chaparral, with a few riparian areas. A warm dry mediterranean climate prevails over the Forest. It is the southernmost National forest of California. It is administered by the United States Forest Service, a government agency within...
and flows generally south-southwest. The West Fork's headwaters rise as a pair of tiny streams, Fry Creek and Iron Springs Creek, just to the north of Palomar Mountain
Palomar Mountain
Palomar Mountain is a mountain in the Peninsular Ranges in northern San Diego County. It is famous as the location of the Palomar Observatory and Hale Telescope, and known for the Palomar Mountain State Park.-History:...
. These two streams combine into the West Fork, which flows southeast through the Mendenhall Valley. The West Fork joins the main stem at Lake Henshaw
Lake Henshaw
Lake Henshaw is a Reservoir in San Diego County, Californiaat the southeast base of Palomar Mountain, approximately miles northeast of San Diego, California and miles southeast of Los Angeles....
, a reservoir formed by a dam across the main stem San Luis Rey River.
From the base of Henshaw Dam, the river winds west along the foot of the Palomars, followed by California State Route 76
California State Route 76
State Route 76 is a state highway in the U.S. state of California. It is an important east–west route in the North County region of San Diego County that begins in Oceanside near Interstate 5 and continues east past Interstate 15 to State Route 79...
. It then bends southwest into a gorge. It leaves the canyon at the wide and spacious Pauma Valley, where it becomes a wash surrounded on both sides by agricultural fields. Potrero and Pauma Creeks enter from the right, then Frey Creek and Agua Tibia Creek as the river travels northwest. The river turns west, passing Pala
Pala, California
Pala is a small, mostly Native American, community located in San Diego County, California near Fallbrook. It is east of Carlsbad in the San Diego-Carlsbad metro area. In the National Geographic Names Database it is officially catalogued as feature number 1661174...
, flowing through a patchwork of privately owned, government-owned and Native American lands. It then crosses under Interstate 15
Interstate 15
Interstate 15 is the fourth-longest north–south Interstate Highway in the United States, traveling through the states of California, Nevada, Arizona, Utah, Idaho, and Montana from San Diego to the Canadian border...
and exits the foothills of the mountains near Bonsall
Bonsall, California
Bonsall is a census-designated place in San Diego County, California. The population was 3,982 at the 2010 census, up from 3,401 at the 2000 census.-Geography:Bonsall is located just east of Oceanside and Camp Pendleton....
.
After passing Bonsall the river flows generally southwest, through the cities of San Luis Rey
San Luis Rey, California
San Luis Rey is an unincorporated community in San Diego County, California. San Luis Rey is along the San Luis Rey River northeast of Oceanside. San Luis Rey has a post office with ZIP code 92068, which was opened in 1861....
and Oceanside
Oceanside, California
-2010:The 2010 United States Census reported that Oceanside had a population of 167,086. The population density was 3,961.8 people per square mile...
. Although usually dry up to this point the river starts to contain water as it nears the mouth, both from seeps and from tidal activity that forms a lagoon
Lagoon
A lagoon is a body of shallow sea water or brackish water separated from the sea by some form of barrier. The EU's habitat directive defines lagoons as "expanses of shallow coastal salt water, of varying salinity or water volume, wholly or partially separated from the sea by sand banks or shingle,...
at the mouth of the river. The San Luis Rey empties into the Pacific north of Oceanside, about 2 miles (3.2 km) south of the Santa Margarita River
Santa Margarita River
The Santa Margarita River is a short intermittent river on the Pacific coast of southern California in the United States, approximately long. One of the last free-flowing rivers in southern California, it drains an arid region of the Coast Ranges between Los Angeles and San Diego at the southern...
and ~30 miles (48.3 km) north of San Diego.