Morris Dam
title: "Morris Dam" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["los-angeles-county-department-of-public-works-dams", "gravity-dams", "san-gabriel-river-(california)", "san-gabriel-mountains", "angeles-national-forest", "azusa,-california", "dams-completed-in-1934", "1934-establishments-in-california", "historic-american-engineering-record-in-california", "historic-civil-engineering-landmarks"] topic_path: "technology/web" source: "https://en.wikipedia.org/wiki/Morris_Dam" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0
::data[format=table title="Infobox dam"]
| Field | Value |
|---|---|
| name | Samuel B. Morris Dam |
| image | Morris-Dam.jpg |
| image_size | 260px |
| image_caption | Morris Dam viewed from the unofficial overlook on State Route 39 (Spillway on left and dam on right) |
| coordinates | |
| country | United States |
| location | Los Angeles County, California |
| status | o |
| construction_began | |
| opening | |
| cost | $25 million |
| owner | Los Angeles County Flood Control District |
| dam_type | Concrete gravity |
| dam_height | 245 ft |
| dam_length | 750 ft |
| dam_crosses | San Gabriel River |
| spillway_type | Gated concrete overflow |
| spillway_capacity | 80000 cuft/s |
| res_name | Morris Reservoir |
| res_capacity_total | 39300 acre.ft (nominal) |
| 27800 acre.ft (current) | |
| res_surface | 417 acre |
| res_elevation | 1152 ft |
| plant_capacity | N/A |
| :: |
| name = Samuel B. Morris Dam | name_official = | image = Morris-Dam.jpg | image_size = 260px | image_caption = Morris Dam viewed from the unofficial overlook on State Route 39 (Spillway on left and dam on right) | image_alt = | location_map = | location_map_size = | location_map_caption = | coordinates = | country = United States | location = Los Angeles County, California | status = o | construction_began = | opening = | demolished = | cost = $25 million | owner = Los Angeles County Flood Control District | dam_type = Concrete gravity | dam_height = 245 ft | dam_height_thalweg = | dam_height_foundation = | dam_length = 750 ft | dam_width_crest = | dam_width_base = | dam_volume = | dam_elevation_crest = | dam_crosses = San Gabriel River | spillway_count = | spillway_type = Gated concrete overflow | spillway_capacity = 80000 cuft/s | res_name = Morris Reservoir | res_capacity_total = 39300 acre.ft (nominal) 27800 acre.ft (current) | res_capacity_active = | res_capacity_inactive = | res_catchment = | res_surface = 417 acre | res_elevation = 1152 ft | res_max_depth = | res_max_length = | res_max_width = | res_tidal_range = | plant_operator = | plant_commission = | plant_decommission = | plant_type = | plant_turbines = | plant_capacity = N/A | plant_annual_gen = | website = | extra =
Morris Dam (officially the Samuel B. Morris Dam) is a concrete gravity dam across the San Gabriel River in the U.S. state of California. It impounds Morris Reservoir, directly downstream of San Gabriel Dam.
The dam was built in the 1930s as a water supply facility for the city of Pasadena, but is now mostly utilized for flood control and flow regulation for groundwater recharge. Situated in northern Los Angeles County, the dam impounds the 417 acre Morris Reservoir in the Angeles National Forest, a few miles northeast of Azusa. From the 1940s to the 1990s, the reservoir was also used for underwater missile testing by the United States military.
Design and location
This dam sits south of Silver Mountain and north of Glendora Ridge, which flank the 1500 ft deep San Gabriel Canyon. It is roughly 37 mi upstream of the San Gabriel River's mouth at the Pacific Ocean, and 6 mi downstream of the river's beginning at the confluence of its East and West Forks. Morris Reservoir is about 3 mi long and 1152 ft above sea level at maximum pool, covering 417 acre.{{cite web |author1=Sheng, Jingfen |author2=Wilson, John P. |url=http://dornsife.usc.edu/geography/ESPE/publications/green_visions_16_green_watershed.pdf |title= Watershed Assets Assessment Report |publisher=USC Dornsife College of Letters, Arts and Sciences |work=The Green Visions Plan for 21st Century Southern California |page=51 |date= |accessdate=2011-07-06}} The dam's crest itself is at an elevation of 1161 ft.{{cite map |publisher=ACME Mapper |title=USGS Topo Maps for United States |year= |cartography=United States Geological Survey |accessdate=2011-07-06 |url=http://mapper.acme.com/}}
Serving mainly flood control, flow regulation and groundwater recharge purposes, the slightly arched Art Deco-style gravity dam is 245 ft high and 750 ft long. Its spillway, located slightly north of the main structure, is a concrete-lined chute controlled by three steel drum gates. The reservoir created by the dam, when first put into use, was capable of storing 39300 acre.ft. Due to sedimentation though since that time, its capacity has been reduced by about 29%. At present, the reservoir when filled holds approximately 27800 acre.ft.{{cite web |url=http://groundwater.fullerton.edu/groundwater/Ongoing_Research/San_Gabriel_Watershed_files/Page%2013.pdf |title=Flood Control and Water Conservation |publisher=California State University Fullerton |work=San Gabriel River Flood Control |date= |accessdate=2011-07-06 |archive-url=https://web.archive.org/web/20120326162124/http://groundwater.fullerton.edu/groundwater/Ongoing_Research/San_Gabriel_Watershed_files/Page%2013.pdf |archive-date=2012-03-26 |url-status=dead
History
Morris Dam was originally slated to be called Pine Canyon Dam, but was renamed for the chief engineer of construction, Samuel Brooks Morris of the Pasadena Water Department.{{cite web |url=http://www.oac.cdlib.org/ark:/13030/kt3x0nd8xp/?layout=metadata&brand=oac4 |title=The Morris San Gabriel Dam, San Gabriel River Canyon, California |publisher=Online Archive of California |date= |accessdate=2011-07-06}} With the dam envisioned as a private structure for Pasadena, groundbreaking was in April 1932 and construction was completed in May 1934, four months behind schedule.{{cite web |url=http://www.ci.azusa.ca.us/documents/Light%20&%20Water/Water/Azusa%20Hydro%20RFP.PDF |title=Hydroelectric Plant Acquisition Study for Azusa Light & Water |publisher=City of Azusa |work=Azusa Light & Water |date=2011-05-17 |accessdate=2011-07-06}} Upon completion the dam was dedicated by former United States President Herbert Hoover.{{cite web |url=http://cdn.calisphere.org/data/13030/6t/tf2489n56t/files/tf2489n56t.pdf |title= Samuel Brooks Morris Papers |publisher=Online Archive of California |date= |accessdate=2011-07-06}} In 1935, contrary to its original purpose, Morris Dam was sold to the Metropolitan Water District of Southern California (MWD), which owned it through most of the 20th century.
::figure[src="https://upload.wikimedia.org/wikipedia/commons/5/51/Morris_11.jpg" caption="The plaque commemorating the old naval weapons test center at Morris Dam"] ::
The dam was completed prior to the catastrophic Los Angeles Flood of 1938, the most severe flood recorded in Southern California since the Great Flood of 1862. Along with San Gabriel Dam, which at the time was under construction, the Cogswell Dam upstream and the Morris Dam greatly reduced the flood peak on the San Gabriel River, saving downstream cities millions of dollars' worth of damages. If it were not for the three dams, the flow past Azusa may have exceeded 150000 cuft/s, but was limited to just 65700 cuft/s, with Morris Dam alone reducing the flood peak by some 30000 cuft/s.
In 2024, the dam was dedicated as a National Historic Civil Engineering Landmark by the American Society of Civil Engineers.
Morris Reservoir Naval Weapons Test Site
Beginning in World War II, Morris Reservoir was used for the Morris Reservoir Naval Weapons Test Site for the U.S. Navy in conjunction with the California Institute of Technology.{{cite web |url=http://ludb.clui.org/ex/i/CA6080/ |title=Morris Reservoir Test Site |publisher=Center for Land Use Interpretation |date= |accessdate=2011-07-06}} A wide variety of weapons, including torpedoes and ballistic missiles, had their trial runs here. Testing continued until the 1990s, when most of the structures at the associated military compound were demolished. However, the concrete foundations remain and are easily seen from State Route 39, which runs past the dam and reservoir. In 1995, MWD sold the dam to the Los Angeles County Department of Public Works, which continues to operate it and the reservoir today.{{cite web |url=http://ladpw.org/wrd/publication/system/canyon.cfm |title=San Gabriel River and Montebello Forebay Water Conservation System |publisher=Los Angeles County Department of Public Works |date= |accessdate=2011-07-06}}
References
Notes
References
- U.S. Geological Survey. National Hydrography Dataset high-resolution flowline data. [http://viewer.nationalmap.gov/viewer/ The National Map], accessed March 10, 2011
- {{cite gnis
- (2006-06-07). "Los Angeles Basin's 1938 Catastrophic Flood Event". Suburban Emergency Management Project.
- Liotta, Jarret. (2024-10-18). "At 90, this San Gabriel Mountains dam has stood the test of time. Now, it’s a landmark". San Gabriel Valley Tribune.
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