Marion, also known as Marion Millpond, is a gravity dam located in Waupaca, Wisconsin, along the North Branch Pigeon river. Built in 1880, this dam serves primarily for recreational purposes, offering hydroelectric power and recreation opportunities. With a structural height of 17 feet and a length of 114 feet, Marion has a storage capacity of 900 acre-feet and a surface area of 108 acres.

Managed by the local government and regulated by the Wisconsin Department of Natural Resources (WIDNR), Marion has a high hazard potential and is classified as very high risk. Despite its age, the dam is in satisfactory condition and undergoes regular inspections, with the last assessment conducted in March 2019. The surrounding area is at risk of inundation, prompting the need for emergency action plans to ensure public safety in case of a dam failure.

With a controlled spillway type and a maximum discharge capacity of 680 cubic feet per second, Marion remains a key water resource for the region. Its historical significance, combined with its vital role in water management and recreation, highlights the importance of continued maintenance and risk management measures to protect the community and the environment.