Thomson Dam No 3, located in Thomson, Minnesota, is a gravity dam completed in 1907 with a primary purpose of hydroelectric power generation. The dam is part of a series of structures including Nos 2-3/4, 3, 3a, 4, and 4a, with a total of 13 associated structures. Managed by the Minnesota Department of Natural Resources, the dam is regulated at both the state and federal levels, with inspections conducted by the Federal Energy Regulatory Commission.

With a height of 38 feet and a length of 1322 feet, Thomson Dam No 3 has a maximum storage capacity of 4352 acre-feet and a normal storage capacity of 4352 acre-feet. The dam, situated on the St. Louis River, has a controlled spillway and a high hazard potential, requiring regular inspections and risk assessments. Despite the lack of available condition assessment data, the dam's emergency action plan was last revised in 2009, indicating preparedness for potential emergencies.

Overall, Thomson Dam No 3 is a significant infrastructure for hydroelectric power generation in Minnesota, showcasing a blend of historical significance and modern regulatory compliance. As climate change continues to impact water resources, the dam's role in managing water flow and generating clean energy becomes even more vital, underlining the importance of regular maintenance and risk management measures to ensure the safety and efficiency of the structure.