Dry Canyon Dam and Reservoir, Santa Clarita, California

Website created and maintained by Stan Walker

Aerial view of the Dry Canyon Reservoir in 1952 taken by the US Department of Agriculture

Copyright Note: This image is NOT in the public domain and is protected by the copyright laws of the United States.
Used by permission of historicalaerials.com

Dry Canyon dam is located on Dry Canyon, a southern flowing tributary of the Santa Clara River, in northeastern Los Angeles County between Seco Canyon and San Francisquito Canyon. Construction started in December of 1910 and finished in February of 1912 at a cost of about $80,700. The dam and reservoir were, and still are, part of the Los Angeles Aqueduct system. Their purpose was to regulate the flow of water from the irregular flow discharged from the power plants in San Francisquito Canyon. The incoming water from San Francisquito came from Tunnel 77 and the outgoing water went out Tunnel 78. Today, the empty reservoir only provides flood control during storms. It also supports a mature cottonwood woodland environment. The property is still owned by the Los Angeles Department of Water and Power.

The dam was constructed using the hydraulic fill method. The central part was pumped into position by the hydraulic pumps. The outer toes were progressively filled with earth by wagons. Steam shovels filled the wagons. See the Final Report in the Annual Reports page for a complete description of the building of the dam. Also, see Lee (1972 - see sources) for more construction information. The original height was 61 feet, but it was later heightened to 66 feet. It is 780 feet in length at an elevation of 1455 feet. The reservoir held about 1,100 acre-feet of water with a surface area of 58 acres. It is owned by the city of Los Angeles.

On October 2, 1913, the first water from the aqueduct reached the reservoir.

In May of 1933, the height of the dam was increased about 5 feet by the Los Angeles Department of Water and Power, increasing the overall storage capacity. This was done to provide more flexibility in the operation of the San Francisquito power plants.

On January 1, 1934, the Bakersfield Californian reported that the Los Angeles Water Bureau had denied reports that the aqueduct was broken. They said that valves in the Dry Canyon reservoir were opened for the purpose of cleansing water in storage there. Airplane pilots, flying over the reservoir, saw water streaming from the dam, leading to the erroneous report that the aqueduct was broken.

In 1941, a new outlet structure was constructed at the dam replacing the original floating weir. The old structure restricted the quantity of water which could be withdrawn from the reservoir.

Silting problems were reported in 1947.

The dam was established as a weather station on July 1, 1948.

The July 21, 1952, Kern County earthquake (7.6 - 7.7 magnatude) caused significant cracking and settlement to the dam, which was located 46 miles from the epicenter. From Hemborg (1955):

"The earthquake damage to this dam consisted of several continuous cracks parallel to the axis along the entire crest and located approximately 5 feet from the downstream edge of crest. These cracks had a maximum opening of 1 1/2 inches and were found to extend down into the hydraulic fill core. Result of check surveys of the dam showed a horizontal displacement of 0.21 foot towards the reservoir and settlement of 0.18 foot."

In response to the quake damage and recognizing its inherant weakness to quakes, the LADWP built a massive, nearly 80 feet high, buttress downstream from the dam (Babbitt, 1993). Also, a thick cap of compacted earth was added to the crest and downstream face of the dam (Keightley, 1963). In the years since the reservoir was drained, the area below the dam saw a massive build-up of homes and the buttress was removed. Dry Canyon creek was converted to a concrete enclosed culvert that drains south parallel to Seco Canyon Road.

In 1955, a mile of 9.5-foot concrete lined tunnel was started as a bypass to the Dry Canyon Reservoir. This was done to alleviate storm water loads at the reservoir. Estimated cost was $1.5 million.

In 1956-57, a new inlet control structure and a 9-foot butterfly valve was installed. The valve would control the flow of water through the bypass when by-passing the reservoir is necessary.

In 1966, the reservoir was drained. Studies were done to determine the feasibility of a partial or complete reconstruction of the dam and reservoir (Lee, 1972) along with a seismic evaluation (Taylor, 1998). The reservoir was apparently never filled again.

In 1969, DWP financial statements budgeted about $810,000 for the reconstruction of the reservoir. And in 1970, the budget for the fiscal year for the City of Los Angeles included $814,000 for reconstruction of the reservoir.

In January of 1971 it was reported (Valley News 1/5/71) that reconstruction work was scheduled to begin in the spring on the reservoir. The project would cost $5,300,000 and would include storm drain water control facilities and rebuilding of the dam. After the 1971 Sylmar quake in February, the project was evidently cancelled because the reservoir was never rebuilt or, for that matter, ever used again as a reservoir.

There was no significant damage to the dam from the February, 9, 1971, 6.6 Sylmar earthquake probably because the reservoir had been drained in 1966. However, there was damage to the aqueduct system (especially the Lower Van Norman Dam in the San Fernando Valley) that required the flow of water to be stopped. This was done at the Fairmont Reservoir (located west of Lancaster in the Antelope Valley). Personnel at the Dry Canyon Reservoir were instructed to trap the remaining water flow in transit from Fairmont and discharge it through the dam's blowoff valves.

I have found no mention of damage to the dam from the Northridge quake of 1994, but by then the dam and reservoir had been virtually out of service for nearly 30 years.

On February 26, 2001, the Santa Monica Mountains Conservancy adapted resolution No. 01-39 authorizing them to exercise the first right of refusal on the Dry Canyon Reservoir property owned by, and declared excess by, the City of Los Angeles Department of Water and Power. The first right of refusal is a contractual right that gives the SMMC the option to buy the property from the LADWP before the LADWP sells it to someone else.

Today, the reservoir acts more like a nature preserve, sort of like the Chatsworth Reservoir in the San Fernando Valley. The aquaduct now passed through the east end of the reservoir property on its way to Bouquet Canyon. At the north end of the reservoir, some water from the aqueduct overflows slightly into the reservoir. It may be possible to divert the water from the aqueduct into the reservoir in case of some emergency, but this is only a guess.

Pages:

Annual Reports of the Los Angeles Aqueduct
Historic Photos
Recent Photos
Sources

Dry Canyon Dam is in the red ellipse. The reservoir is the green area above it. Seco Canyon Road is the blue line and its northern end points to the dam (from google maps).

This cross section of the dam shows the original dam (1912) and the part that was added in 1953 in response to the 1952 earthquake (from Keightly, 1963). You can also see the original cross section on Plate 18 on the Annual Reports page.

Keightley did some vibration tests on the dam in 1963 for his CIT thesis. Here are the "shaking machines" from the above diagram.

Here is another cross section of the dam (from Lee, 1972)

Some of the 1952 earthquake damage (from Lee, 1972)

From the Oakland Tribune of 10/3/1913

This map is from 1968. It shows the routes of both the first aqueduct and the second aqueduct (still under construction then - completed in 1970).

Legend: A = Owens River, B = Independence, C = Mt. Whitney, D = Second LA aqueduct intakes, E = Tehachapi, F = San Francisquito Power Plant No. 2, G = Dry Canyon Reservoir, H = Cascades, I = Susana Trunk Line, J = Tujunga trunk line, K = Cascades, L = San Fransciquito Power Plant No. 1, M = Bouquet Reservoir, N = power plant, O = Waiweee Reservoir, P = Owens Dry Lake, Q = Lone Pine, R = First LA aqueduct intakes.