Lake Herman Reservoir Report

Last Updated: December 5, 2025

Lake Herman, located in Solano County, California, is a vital water resource managed by the local government for irrigation and water supply purposes.


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Summary

The dam, completed in 1905, stands at a height of 51 feet and has a storage capacity of 2,210 acre-feet. With a surface area of 110 acres, the lake serves as a key source of water for the surrounding area, drawing from Sulphur Springs Creek.

Despite its age, Lake Herman's dam is in satisfactory condition and is regularly inspected by state regulatory agencies to ensure its safety and functionality. The dam's high hazard potential necessitates a thorough emergency action plan, although specific details such as inundation maps and risk assessments are not yet available. The dam's proximity to Benecia and its role in water management highlight the critical importance of maintaining and monitoring this key infrastructure in the face of changing climate patterns and water resource demands.

Year Completed

1905

Dam Length

700

Dam Height

51

River Or Stream

Sulphur Springs Cr

Primary Dam Type

Earth

Surface Area

110

Hydraulic Height

44

Nid Storage

2210

Hazard Potential

High

Nid Height

51
       
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.