Nielson (John) Reservoir Report

Last Updated: December 5, 2025

Nielson (John) is a private water supply dam located in Emery, Utah, with a significant hazard potential.


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Summary

Managed by the Utah Division of Water Rights, this off-channel dam stands at a hydraulic height of 32 feet and a structural height of 36 feet, with a storage capacity of 180 acre-feet. Completed a number of years ago, this earth dam spans 430 feet in length and serves as a vital resource for the surrounding area.

Despite its critical role in water supply, Nielson (John) has not been rated for its condition, and the last inspection in September 2020 revealed that it was not assessed. The dam poses a significant risk, although specific risk management measures have not been outlined. With a regulated state jurisdiction and permitting, inspection, and enforcement in place, this dam remains a focal point for water resource enthusiasts interested in the management and maintenance of essential infrastructure in the region.

As a key element of the water supply infrastructure in Emery County, Utah, Nielson (John) represents a blend of private ownership and state oversight. With a capacity to hold 180 acre-feet of water and a history of state-regulated operations, this dam underscores the importance of maintaining and managing water resources in a region susceptible to climate variability. Enthusiasts interested in the intersection of water resources and climate change will find Nielson (John) a compelling case study in the ongoing efforts to secure sustainable water supplies for the future.

Dam Length

430

River Or Stream

OFF CHANNEL

Primary Dam Type

Earth

Hydraulic Height

32

Nid Storage

180

Structural Height

36

Hazard Potential

Significant

Nid Height

36
       
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.