Lake Aloha Auxiliary No. 4 Reservoir Report

Last Updated: December 4, 2025

Lake Aloha Auxiliary No.


°F

°F

mph

Wind

%

Humidity

Summary

4, also known as Medley Lakes Auxiliary No. 4, is a private water resource located in El Dorado County, California, near South Lake Tahoe. This hydroelectric facility, completed in 1917, serves multiple purposes including hydroelectric power generation and irrigation. The dam, a rockfill structure standing at 9 feet tall with a structural height of 8.5 feet, contributes to the storage of water in the South Fork American River watershed.

With a storage capacity of 5063 acre-feet and a surface area of 630 acres, Lake Aloha Auxiliary No. 4 plays a crucial role in water management and conservation in the region. Although classified as having a low hazard potential, its risk assessment is considered high, emphasizing the importance of regular inspections and adherence to safety protocols. Managed by the Federal Energy Regulatory Commission, this dam is subject to state regulations and inspections to ensure its integrity and safety for the surrounding community and environment.

Year Completed

1917

Dam Length

112

Dam Height

9

River Or Stream

South Fork American River

Primary Dam Type

Rockfill

Surface Area

630

Hydraulic Height

6

Drainage Area

3.4

Nid Storage

5063

Structural Height

8.5

Hazard Potential

Low

Nid Height

9
       
Seasonal Comparison

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.