ArborWiki’s entry for Barton Dam says that:
Barton Dam is one of Ann Arbor’s four dams on the Huron River. It was designed by engineer Gardner Stewart Williams and architect Emil Lorch and built in 1912-13 as part of the development of hydroelectric power on the Huron River by the predecessor of Detroit Edison. The earthen-construction dam is 34 feet high and 1767 feet long, and has a typical surface area of 315 acres and typical storage of 5050 acre-feet. The dam can be accessed from Huron River Drive from the city park located at the foot of Bird Road.
The City of Ann Arbor purchased the dam from Detroit Edison in the 1960s, and restarted hydroelectric generation in the 1980s. The facility has a 900-kilowatt turbine that generates 4.2 million kWh per year.
In case you’re wondering, Emil Lorch (1870-1963) was the first University of Michigan Dean of Architecture and – as this page from the Bentley Historical Library explains, Gardner Stewart Williams was the engineer who worked with the Detroit Edison Company to identify sites for dams to generate power on the Huron in the early 1900s. There’s also a Flickr group for Barton Dam where you can see a lot more photos!