Lake Sullivan dam inspection report

Engineers with the Minnesota Department of Natural Resources inspected the Lake Sullivan dam on April 14, 2015. This dam is exempt from Dam Safety Regulations but is inspected about once every eight years because it is owned by DNR.

LS-Dam-April2015The present dam was built in 1935 for lake level control and to prevent carp from entering the lake from the Mississippi River. In 1950 the catwalk was removed and all piers were shortened. The dam had six stop log bays with each being 5.75 feet wide. The dam presently has a concrete weir about 15 inches above the sill.

The existing dam is in fair to poor condition but it is functional and fairly stable. The concrete is in fair condition with several areas of exposed rebar and other concrete deterioration due to weathering. The concrete also shows signs of structural distress as evidenced by large cracks and leaning abutments.

The earthen embankments flanking either side of the dam are 1 to 2 feet below the concrete abutments. Embankments are lowest adjacent to both abutments, likely the result of shifting of the abutments. The dikes are stable. Routine mowing or other measures are recommended to control the growth of vines and brush.

Due to water flowing over the concrete weir Dam Safety was unable to evaluate the condition of the weir. The weir was repaired in 2007 to reduce leakage through the dam. At the time of this inspection no debris was in the spillway that would obstruct the flow of water.

Dam Safety is currently monitoring the dam and is committed to make necessary repairs to maintain current lake levels until funding to repair the dam is obtained. The dam is maintaining water levels as intended. Dam Safety did not observe any structural deficiency requiring immediate attention to maintain the dam in its current state. Future repair should address the tilting concrete abutments, repairing deteriorated concrete and adding earth fill to the embankment.

Click here to download the full report and photos.

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