Cogswell Reservoir

Reservoir Levels Weather Hydrology

Cogswell Reservoir is a man-made reservoir located in the San Gabriel Mountains of Los Angeles County, California. The reservoir was built in 1954 by the Los Angeles County Department of Public Works as part of the San Gabriel River Watershed. It is a significant source of drinking water for the region and can store up to 8,000 acre-feet of water.

Cogswell Reservoir is fed by both surface flow and snowpack from the San Gabriel Mountains. The San Gabriel River, which originates from the mountains, is the primary surface flow provider to the reservoir. Snowmelt from the surrounding mountains also contributes to the reservoir's water supply.

The water from Cogswell Reservoir is used for both agricultural and recreational purposes. The water is mainly used for irrigation in the San Gabriel Valley, while recreational activities such as fishing, boating, and hiking are also popular in the area. The reservoir is managed by the Los Angeles County Department of Public Works and is an important source of water for the region.

June 22, 2024







Storage 24hr Change None%
Percent of Normal None%
Minimum 15 acre-ft
Maximum 8,892 acre-ft
Average acre-ft
Nid_Height 266
Hydraulic_Height 239
Primary_Dam_Type Rockfill
Drainage_Area 38.4
Year_Completed 1935
Dam_Height 266
Hazard_Potential High
River_Or_Stream Wfk San Gabriel R
Surface_Area 146
Nid_Storage 8969
Dam_Length 585

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