Thompson No 1 Main Dam, located in Nez Perce, Idaho, is a privately owned structure built in 1967 for irrigation purposes. This Earth-core, Stone foundation dam stands at a height of 17.4 feet, with a hydraulic height of 15.1 feet, providing a storage capacity of 54 acre-feet. The dam spans 580 feet in length and covers a surface area of 6.1 acres, serving the local community's water needs from Springs Little Canyon Creek.

Despite its fair condition assessment as of July 2017, the dam poses a significant hazard potential, with a high risk rating of 2. Regular state inspections and enforcement ensure its compliance with safety regulations, with the Idaho Department of Water Resources serving as the primary regulatory agency. The dam lacks a spillway, indicating a need for potential risk management measures to mitigate any emergencies and safeguard the surrounding area from inundation.

Water resource and climate enthusiasts can appreciate the strategic importance of Thompson No 1 Main Dam in sustaining agricultural activities in the region, while also recognizing the need for continued monitoring and maintenance to ensure its long-term safety and functionality. With its picturesque location and vital role in water management, this dam serves as a critical piece of infrastructure that highlights the intricate balance between human development and environmental conservation in the face of changing climatic conditions.