Thornapple is a historic hydroelectric dam located in Holcombe, Wisconsin, along the Flambeau River. Built in 1909, this gravity dam stands at 14 feet high and spans 530 feet in length, with a storage capacity of 2400 acre-feet and a drainage area of 1850 acres. The dam serves multiple purposes, including hydroelectric power generation and recreation, making it a vital resource for the local community.

Managed by the Federal Energy Regulatory Commission, Thornapple has a controlled spillway with a width of 370 feet and is equipped with 22 Tainter radial gates for efficient water flow regulation. Despite being classified as having a low hazard potential, Thornapple poses a very high risk due to its age and location. While the condition assessment is not available, regular inspections and emergency action plans are in place to ensure the dam's safety and integrity.

With its rich history and significant role in providing clean energy and recreational opportunities, Thornapple is a notable structure within the water resource and climate enthusiasts' community. As efforts are made to manage the risks associated with this aging dam, it remains a symbol of the intricate balance between harnessing natural resources for human benefit while ensuring environmental sustainability and safety.