Hansen Dam is a
dam
A dam is a barrier that stops or restricts the flow of surface water or underground streams. Reservoirs created by dams not only suppress floods but also provide water for activities such as irrigation, human consumption, industrial use, aqua ...
built for
flood control
Flood management or flood control are methods used to reduce or prevent the detrimental effects of flood waters. Flooding can be caused by a mix of both natural processes, such as extreme weather upstream, and human changes to waterbodies and ru ...
in the northeastern
San Fernando Valley
The San Fernando Valley, known locally as the Valley, is an urbanized valley in Los Angeles County, Los Angeles County, California. Situated to the north of the Los Angeles Basin, it comprises a large portion of Los Angeles, the Municipal corpo ...
, in the
Lake View Terrace neighborhood of
Los Angeles, California
Los Angeles, often referred to by its initials L.A., is the List of municipalities in California, most populous city in the U.S. state of California, and the commercial, Financial District, Los Angeles, financial, and Culture of Los Angeles, ...
.
[Pitarre, Alyson. "Where country living sidles up to the city." '']Los Angeles Times
The ''Los Angeles Times'' is an American Newspaper#Daily, daily newspaper that began publishing in Los Angeles, California, in 1881. Based in the Greater Los Angeles city of El Segundo, California, El Segundo since 2018, it is the List of new ...
''. June 12, 2005
1
Retrieved March 19, 2010. The dam was built by the
U.S. Army Corps of Engineers
The United States Army Corps of Engineers (USACE) is the military engineering branch of the United States Army. A direct reporting unit (DRU), it has three primary mission areas: Engineer Regiment, military construction, and civil wor ...
, Los Angeles District in 1940. Hansen Dam was named after horse ranchers Homer and Marie Hansen, who established a ranch in the 19th century.
The Hansen Dam Recreation Center is located in the flood control basin and surrounding slopes behind the dam.
[laparks: Hansen Dam recreation center](_blank)
. Retrieved February 1, 2012
Geography
Hansen Dam and its once-designed lake are now seasonal flood spreading grounds in the
San Fernando Valley
The San Fernando Valley, known locally as the Valley, is an urbanized valley in Los Angeles County, Los Angeles County, California. Situated to the north of the Los Angeles Basin, it comprises a large portion of Los Angeles, the Municipal corpo ...
on
Tujunga Wash
Tujunga Wash is a U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map accessed March 16, 2011 stream in Los Angeles County, California. It is a tributary of the Los Angeles River, providing about a f ...
. Tujunga Wash begins between the
San Gabriel Mountains
The San Gabriel Mountains () are a mountain range located in Los Angeles and San Bernardino counties, California, United States. The mountain range is part of the Transverse Ranges and lies between the Los Angeles Basin and the Mojave Desert ...
and
Verdugo Mountains
The Verdugo Mountains, also known as the Verdugo Hills or simply The Verdugos, are a small, rugged mountain range of the Transverse Ranges system in Los Angeles County, California. Located just south of the western San Gabriel Mountains, the Verdu ...
. The dam is downstream from the confluence of the
Big Tujunga Creek
Big Tujunga Creek is a major stream in Los Angeles County in the U.S. state of California. From its headwaters high in the San Gabriel Mountains, it flows generally southwest for ,U.S. Geological Survey. National Hydrography Dataset high-resolutio ...
and Little Tujunga Creek-Wash. The dam contains a
reservoir
A reservoir (; ) is an enlarged lake behind a dam, usually built to water storage, store fresh water, often doubling for hydroelectric power generation.
Reservoirs are created by controlling a watercourse that drains an existing body of wa ...
, which is sometimes referred to as Hansen Lake. The spillway structure, outlet works and channel are located near the center of the Dam's rock embankment. The embankment itself follows a slight curve that creates a natural barrier by connecting the hills at either end of the dam.
It is southeast of the city of
San Fernando.
History
The
Los Angeles Flood of 1938, which included significant flooding along the Tujunga Wash and at its
confluence
In geography, a confluence (also ''conflux'') occurs where two or more watercourses join to form a single channel (geography), channel. A confluence can occur in several configurations: at the point where a tributary joins a larger river (main ...
with the
Los Angeles River
The Los Angeles River (), historically known as by the Tongva and the by the Spanish, is a major river in Los Angeles County, California. Its headwaters are in the Simi Hills and Santa Susana Mountains, and it flows nearly from Canoga Park ...
, resulted in increased support to dam and channelize the city's creeks and rivers. In 1939, due to repeated floods and the damage they caused in the eastern portions of the San Fernando Valley, the U.S. Army Corps of Engineers began the project. The Corps worked in conjunction with the
Los Angeles County Flood Control District
The Los Angeles County Department of Public Works (LACDPW) is responsible for the construction and operation of Los Angeles County's roads, building safety, sewerage, and flood control. DPW also operates traffic signals and intelligent transportat ...
(LACFCD). They had already considered planning to implement
flood risk management
Flood management or flood control are methods used to reduce or prevent the detrimental effects of flood waters. Flooding can be caused by a mix of both natural processes, such as extreme weather upstream, and human changes to waterbodies and ru ...
within the area since 1915 after a previous series of floods.
In 1939 the Corps, by use of
eminent domain
Eminent domain, also known as land acquisition, compulsory purchase, resumption, resumption/compulsory acquisition, or expropriation, is the compulsory acquisition of private property for public use. It does not include the power to take and t ...
, seized the horse ranch of Homer and Marie Hansen to build the dam.
After a year of construction and over $11 million in initial costs, the dam and its corresponding facilities were finished.
The long, high dam was built to control the runoff and floodwaters.
During storms and flooding, the dam is intended to catch water within the reservoir. Provisions in the dam's standards of operations promote
water conservation
Water conservation aims to sustainably manage the natural resource of fresh water, protect the hydrosphere, and meet current and future human demand. Water conservation makes it possible to avoid water scarcity. It covers all the policies, strateg ...
efforts coordinated with the
Los Angeles County Department of Public Works
The Los Angeles County Department of Public Works (LACDPW) is responsible for the construction and operation of Los Angeles County, California, Los Angeles County's roads, building code, building safety, Sewage collection and disposal, sewerage, an ...
. The provisions allow the dam to discharge water onto spreading grounds located south of the dam, which then percolates into
groundwater recharge
Groundwater recharge or deep drainage or deep percolation is a hydrologic process, where water moves downward from surface water to groundwater. Recharge is the primary method through which water enters an aquifer. This process usually occurs in ...
basins and is stored as part of the city's water supply.

Accumulation of debris from previous floods reduced the amount of storage capacity of the reservoir. As a result, in 1981, the Corps proposed raising the height of the dam rather than starting the expensive process of removing the build up of silt, sand, gravel and other debris. The proposal did not pass, and responsibility was redirected back to the Corps providing maintenance of the dam. The Corps must occasionally excavate sediment and vegetative debris to clear clogged outlet works and maintain full capacity of the dam.
In the mid-1940s, the Hansen Dam Basin's recreational possibilities were considered as it attracted thousands of visitors every year. Development of recreational facilities began in 1952 with the creation of Holiday Lake, which was used by swimmers, boaters, and anglers. By 1991, the lake had become completely filled with sediment and was abandoned.
Hansen Dam Recreation Area

The Hansen Dam Recreation Center and Park are located here, with extensive day use facilities operated by the City of Los Angeles Department of Recreation and Parks. Most facilities are accessed from Highways 5 and/or 210.
The Hansen Dam Horse Park and Hansen Dam Aquatic Center are located behind the dam here, and Hansen Dam Golf Course in front.
Recreation Center and Park features a moderate size lake which is filled with circulated drinking water and offers fishing and public boating. The lake is open year-round, including holidays, but may be closed during times of severe weather or for planned events.
Also at the site is located a smaller swim lake which features water that is filtered and chlorinated and has a capacity of 2,800 swimmers.
The City of Los Angeles Department of Recreation and Parks provides lifeguards who service to the three lakes within the flood control basin.
The recreation center and park areas also have: picnic tables and barbecue pits, children's play areas; and baseball diamonds and soccer fields.
The park features equestrian and walking trails, that link to those exploring the nearby
Angeles National Forest
The Angeles National Forest (ANF) of the United States Forest Service is located in the San Gabriel Mountains and Sierra Pelona Mountains, primarily within Los Angeles County in Southern California. The ANF manages a majority of the San Gabri ...
, and a walking pathway along the dam's top. The habitats include
montane chaparral and woodlands and
riparian
A riparian zone or riparian area is the interface between land and a river or stream. In some regions, the terms riparian woodland, riparian forest, riparian buffer zone, riparian corridor, and riparian strip are used to characterize a ripar ...
in the rustic areas. The basin is a resource of large open space for the Los Angeles region. A large portion of the area remains undeveloped in an effort to conserve natural habitats and maintain the diverse animal and plant species.

The Hansen Dam Park natural area's ecology is being
restored
''Restored'' is the fourth studio album by American contemporary Christian musician Jeremy Camp. It was released on November 16, 2004, by BEC Recordings.
Track listing
Standard release
Enhanced edition
Deluxe gold edition
Standard Aus ...
, with
invasive plant
An invasive species is an introduced species that harms its new environment. Invasive species adversely affect habitats and bioregions, causing ecological, environmental, and/or economic damage. The term can also be used for native speci ...
s removal and
native plant
In biogeography, a native species is indigenous to a given region or ecosystem if its presence in that region is the result of only local natural evolution (though often popularised as "with no human intervention") during history. The term is equi ...
reintroduction. The proposed
Rim of the Valley Trail Corridor would include Hansen Dam Park as a significant hub with trailheads.
The Discovery Cube Los Angeles is located at the northwest corner of the recreation area on the intersection of Osborne St. and Foothill Blvd. It was built in November 2014 and was intended to serve as an extension campus of the
Discovery Cube Orange County. It has a mix of both traveling and permanent exhibits, which includes work done by the Los Angeles Bureau of Sanitation for waste reduction and resource conservation. It also has sponsored areas by the
Los Angeles Department of Water and Power
The Los Angeles Department of Water and Power (LADWP) is the largest municipal Public utility, utility in the United States with 8,100 megawatts of electric generating capacity (2021–2022) and delivering an average of 435 million gallons of wat ...
that educate visitors about sustainability, water conservation and preserving natural resources.
In 2015,
KTTV
KTTV (channel 11) is a television station in Los Angeles, California, United States, serving as the West Coast of the United States, West Coast flagship (broadcasting), flagship station of the Fox Broadcasting Company, Fox network. It is owned a ...
reported that unhoused people were camping at Hansen Dam as a result of
California's growing housing crisis.
In September 2015, a $300,000 cleanup effort was initiated.
Recreational Assets
* Discovery Cube Los Angeles
* Aquatic Center
* Playground
* Skate Park
* Picnic Area
* Sports Center
* Equestrian Center
* Bike Trail
See also
*
Creek Fire (2017)
*
Index: Parks in the San Fernando Valley
*
List of California native plants
California native plants are plants that existed in California prior to the arrival of European explorers and colonists in the late 18th century. California includes parts of at least three phytochoria. The largest is the California Floristi ...
*
List of dams and reservoirs in California
Following is a list of dams and reservoirs in California in a sortable table. There are over 1,400 named dams and 1,300 named reservoirs in the state of California.
Dams in service
:''Please add to this list from the below sources.''
Former ...
References
External links
official Hansen Dam Recreation Center website- ''from Los Angeles Recreation and Parks.''
Orcas-Gabreieleno Equestrian Center
{{-
Parks in the San Fernando Valley
Parks in Los Angeles
Dams in Los Angeles County, California
United States Army Corps of Engineers dams
Dams completed in 1940
Buildings and structures in the San Fernando Valley
Landmarks in Los Angeles
Los Angeles River
Lake View Terrace, Los Angeles
San Fernando Valley