Morena Dam Reservoir Report

Last Updated: December 5, 2025

Morena Dam is a concrete arch dam located in San Diego County, California.


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Summary

It was built in 1912 by the Morena Rock Company to provide irrigation water for crops in the surrounding areas. The dam has a height of 155 feet and a length of 540 feet. It impounds the waters of the Cottonwood Creek and is used as a storage reservoir for the City of San Diego.

The hydrology of the dam is sourced from both surface flow and snowpack. The dam collects water from the Cottonwood Creek and from the mountainous regions surrounding the area. The snowmelt from the nearby Laguna Mountains also contributes to the water supply of the dam. The water stored in the dam is used for agricultural purposes and for recreation, including fishing and boating.

The dam has faced a few challenges in the past, including the 2003 Cedar Fire, which burnt a significant portion of the watershed that supplies water to the dam. Despite this, the dam has continued to provide a reliable water supply to the surrounding communities.

Reservoir Details

Storage 24hr Change None%
Percent of Normal None%
Minimum 3,448.0 acre-ft
2022-12-04
Maximum 12,515.0 acre-ft
2023-07-03
Average acre-ft
Nid_Height 181
Hydraulic_Height 167
Drainage_Area 114
Year_Completed 1912
Dam_Height 181
Primary_Dam_Type Rockfill
Surface_Area 1475
Hazard_Potential High
Nid_Storage 50206
River_Or_Stream Cottonwood Cr
Dam_Length 550
       
Seasonal Comparison
Storage Levels
Pool Elevation Levels
Top Conserv Storage Levels
Inflow Levels

Weather Forecast

Dam Data Reference

Condition Assessment

Satisfactory
No existing or potential dam safety deficiencies are recognized. Acceptable performance is expected under all loading conditions (static, hydrologic, seismic) in accordance with the minimum applicable state or federal regulatory criteria or tolerable risk guidelines.
Fair
No existing dam safety deficiencies are recognized for normal operating conditions. Rare or extreme hydrologic and/or seismic events may result in a dam safety deficiency. Risk may be in the range to take further action. Note: Rare or extreme event is defined by the regulatory agency based on their minimum
Poor A dam safety deficiency is recognized for normal operating conditions which may realistically occur. Remedial action is necessary. POOR may also be used when uncertainties exist as to critical analysis parameters which identify a potential dam safety deficiency. Investigations and studies are necessary.
Unsatisfactory
A dam safety deficiency is recognized that requires immediate or emergency remedial action for problem resolution.
Not Rated
The dam has not been inspected, is not under state or federal jurisdiction, or has been inspected but, for whatever reason, has not been rated.
Not Available
Dams for which the condition assessment is restricted to approved government users.

Hazard Potential Classification

High
Dams assigned the high hazard potential classification are those where failure or mis-operation will probably cause loss of human life.
Significant
Dams assigned the significant hazard potential classification are those dams where failure or mis-operation results in no probable loss of human life but can cause economic loss, environment damage, disruption of lifeline facilities, or impact other concerns. Significant hazard potential classification dams are often located in predominantly rural or agricultural areas but could be in areas with population and significant infrastructure.
Low
Dams assigned the low hazard potential classification are those where failure or mis-operation results in no probable loss of human life and low economic and/or environmental losses. Losses are principally limited to the owner's property.
Undetermined
Dams for which a downstream hazard potential has not been designated or is not provided.
Not Available
Dams for which the downstream hazard potential is restricted to approved government users.