The original settlers to the area were drawn, in large part, to the Milwaukee River. The river provided a rich source of fish and game, transportation, and water power. The actual construction of the dam and flour mill started after John Weston sold his property to John Henry Thien in the summer of 1842. In all likelihood, the dam and foundation for the flour mill were built simultaneously during the low water of late summer of 1842. Recognizing the power offered by the 6.5 foot tall raceway impoundment, Thien added a sawmill between the dam and his flour mill in 1843.

The first flour mill, a three story wooden structure, burned to the ground in 1874 during one of Thiensville’s frequent bog fires. A second flour mill, a five story stone structure, was built in 1876 and served the farming community until just after World War II. The building fell into disrepair and was eventually razed in 1956. The dam also fell into disrepair following the failure of the Thiensville Milling Company in 1939. Recognizing the importance of the impoundment to recreation in the area and the value of over 200 properties upstream, ownership of the dam was transferred to the Mequon Township Advancement Association in 1941. In 1962, the group now known as the Mequon-Thiensville Advancement Association transferred ownership of the dam to the City of Mequon (75%) and the Village of Thiensville (25%). That shared ownership of the dam and raceway (which became a fishway in 2011) remains in effect today.