Willow River (St. Croix River tributary)
General data
- Name: Willow River (St. Croix River tributary)
- Water system: Mississippi River
- Water type: River
- Progression: St. Croix River (Wisconsin–Minnesota) -> Mississippi River -> Gulf of Mexico -> Atlantic Ocean -> Planet Earth
- Climates: Temperate
- Continents: North America
- Countries: United States of America
The Willow River is a 61.1-mile-long (98.3 km) river in St. Croix County, Wisconsin, United States, and a tributary of the St. Croix River.
Its source is in southern Polk County east of the village of Clear Lake. The river at one time flowed unobstructed into the lower St. Croix River between Hudson and North Hudson (44°59′18″N 92°45′46″W).
However a dam was built to block off its mouth, a narrow channel was cut above the dam to the St. Croix River, the channel was dammed, and a mill was built to exploit the head of water that the two dams created.
Subsequently, the Willow River Power Company built a hydroelectric facility to utilize the same head of water, but the head was substantially decreased when the United States built the Red Wing Dam 30 miles (48 km) downstream on the Mississippi River.