Thompson No 2 Reservoir Report

Last Updated: January 11, 2026

Thompson No 2 is a privately-owned irrigation structure located in Idaho, specifically in Clearwater County.


°F

°F

mph

Wind

%

Humidity

Summary

Completed in 1970, this earth dam stands at a height of 18.5 feet and has a storage capacity of 14.6 acre-feet, serving the primary purpose of irrigation. The dam is built with a core of stone and rests on rock and soil foundations, with a surface area of 2.25 acres and a drainage area of 0.1 square miles.

With a significant hazard potential and fair condition assessment, Thompson No 2 is regulated by the Idaho Department of Water Resources. The dam's spillway type is uncontrolled, with a maximum discharge of 1 cubic foot per second. Despite its moderate risk assessment rating, the dam has not undergone any significant modifications since its completion. The last inspection in October 2016 revealed a fair condition, indicating the need for continued monitoring and maintenance of this vital water resource structure in the region.

For water resource and climate enthusiasts, Thompson No 2 offers a fascinating glimpse into the intricate infrastructure supporting irrigation in Idaho. As a crucial component of the local water management system, this dam plays a vital role in ensuring efficient water distribution for agricultural purposes. With its strategic location on the Spring Clearwater River, Thompson No 2 stands as a testament to the ingenuity and engineering prowess involved in harnessing water resources for sustainable development in the region.

Year Completed

1970

Dam Length

480

Dam Height

18.5

River Or Stream

SPRING CLEARWATER RIVER

Surface Area

2.25

Hydraulic Height

16.2

Drainage Area

0.1

Nid Storage

14.6

Hazard Potential

Significant

Foundations

Rock, Soil

Nid Height

19
       
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.