Williams Valley Reservoir Report

Last Updated: December 13, 2025

Williams Valley is a privately owned dam located in Dos Rios, Mendocino County, California.


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Summary

Completed in 1965, this earth dam stands at a height of 47 feet and serves primarily for water supply purposes, including irrigation and tailings. With a storage capacity of 200 acre-feet and a drainage area of 1.4 square miles, Williams Valley plays a crucial role in water resource management in the region.

Managed by the California Department of Water Resources (DWR) and regulated by the Safety of Dams agency, Williams Valley has a low hazard potential and is currently in satisfactory condition. The dam undergoes regular inspections, with the last assessment conducted in September 2017. With a hydraulic height of 39 feet and a length of 243 feet, this structure contributes to the sustainable utilization of the Tr Short Creek for various agricultural and domestic water supply needs in the area.

Representing a significant asset for the community, Williams Valley operates under the oversight of state regulatory agencies and ensures compliance with safety standards. The dam's location, in close proximity to the Sacramento District, underscores its strategic importance in water management practices. Climate and water resource enthusiasts will appreciate the vital role that Williams Valley plays in maintaining the water supply infrastructure and supporting sustainable development in the region.

Year Completed

1965

Dam Length

243

Dam Height

47

River Or Stream

Tr Short Creek

Primary Dam Type

Earth

Surface Area

15

Hydraulic Height

39

Drainage Area

1.4

Nid Storage

200

Hazard Potential

Low

Nid Height

47
       
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.