Mann Creek Dam (National ID # ID00285) is a dam in Washington County, Idaho, in the western part of the state, a few miles north-northeast of the town of Weiser.
The earthen dam was an irrigation project of the United States Bureau of Reclamation. Completed in 1967, the dam impounds Mann Creek with a height of above bedrock, and a length of along its crest. The dam is operated by the local Mann Creek Irrigation District.
Mann Creek Reservoir has a surface area of at an elevation of . At closure it had a maximum capacity of but siltation reduced that number to by 1992. The western side of the lake is the location of the former Mann Creek State Park. Boating and fishing are the main recreational activities.