Hopkinton Dam and Rock Dam


River/Stream: Maquoketa River

Location: southwest of Hopkinton, Delaware County
        Latitude: 42.337801
        Longitude: -91.257792
        Click here to view an aerial map of the dam.

Built: 1844 power for saw mill, 1853 power for flour mill, 1892 electric power generation, 192X power generation decommissioned. Partially removed and converted to rock riffle in 2002.

Owner: Delaware County Conservation

Height: formerly 12 ft.

Length: 150 ft.

Hazards: formerly usage, visibility

Warning Signs:

Portage: on river-right (west bank). This is not so much a dam as it is a vigorous and at times impassable boulder-strewn waterfall which cascades down a short, shallow drop. Paddle up to the right side under the bridge and look for a concrete path just a few feet up the bank. Follow the path about 40 yards down to the low end of the riffle and put in.

Comments: Approximately one half mile upstream from this feature, the Maquoketa splits into the primary SW channel and a smaller NE channel. There is another rock dam approximately 1000 feet NE of this site where another bridge crosses the NE channel. That rock dam was build for recreation and erosion control and includes formed concrete. Click here to view an aerial map of the rock dam.


View of dam mitigated to rock riffle

View of dam mitigated to rock riffle

Remainder of old dam after conversion

Remainder of old dam after conversion