Hill Dam Number 1 Reservoir Report
Last Updated: December 13, 2025
Located in Washoe, Nevada, Hill Dam Number 1 was completed in 1911 by the USDA NRCS and serves as a vital water resource for irrigation purposes.
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Summary
The dam stands at a height of 22 feet, with a hydraulic height of 17.5 feet and a structural height of 25 feet, holding a maximum storage capacity of 660 acre-feet and a normal storage of 450 acre-feet. Situated on Mosquito Creek, the dam has a low hazard potential but is currently assessed as being in poor condition, highlighting the need for maintenance and upgrades to ensure its continued functionality.
Despite its age, Hill Dam Number 1 remains an essential infrastructure for fire protection, stock watering, and small fish pond purposes in the region. The dam spans a length of 325 feet and has a spillway width of 20 feet, allowing for a maximum discharge of 200 cubic feet per second. Although the dam has undergone modifications in 1954 to enhance its hydraulic and structural integrity, ongoing inspections by the Nevada DWR are necessary to monitor its condition and safety. With a moderate risk assessment rating, proper risk management measures must be implemented to mitigate any potential hazards associated with the dam.
As a privately owned dam in a state-regulated jurisdiction, Hill Dam Number 1 is subject to regular inspections and enforcement by the Nevada DWR to ensure compliance with safety standards. Despite its current poor condition assessment, the dam's historical significance and essential role in water resource management underscore the importance of investing in its maintenance and upkeep. With careful monitoring and proactive risk management measures, Hill Dam Number 1 can continue to support irrigation and other water-related activities in the Washoe County area for years to come.
Years Modified |
1954 - Hydraulic, 1954 - Structural |
Year Completed |
1911 |
Dam Length |
325 |
Dam Height |
22 |
River Or Stream |
MOSQUITO CREEK |
Primary Dam Type |
Earth |
Surface Area |
80 |
Hydraulic Height |
17.5 |
Drainage Area |
2.5 |
Nid Storage |
660 |
Structural Height |
25 |
Outlet Gates |
Slide (sluice gate) - 1 |
Hazard Potential |
Low |
Foundations |
Rock |
Nid Height |
25 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Mahogany Creek Near Summit Lake
|
2cfs |
Sf Pit R Nr Likely Ca
|
7cfs |
Pit R Nr Canby Ca
|
63cfs |
Dam Data Reference
Condition Assessment
SatisfactoryNo 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
HighDams 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.
Hill Dam Number 1