CONTINUED MONITORING OF THE GEOMORPHOLOGICAL AND SEDIMENTOLOGICAL CHANGES TO THE MIDDLE CUYAHOGA RIVER, OHIO, AS A RESULT OF TWO DAM REMOVALS

The Monroe Falls Dam was removed in 2005, and further downstream, the LeFever Dam was removed in 2013 in order to improve water quality of the middle Cuyahoga River, Summit County, OH. These dam removals increased the slope and stream power of the middle Cuyahoga River. Geomorphology profiling and channel sediment grain size studies begun in 2004 were re-measured in 2018 in order to determine the long-term channel response to the dam removals. In September of 2018, fifteen channel transects were measured using a transit and stadia rod. The grain size distribution of twenty-seven channel sediment samples was determined by sieve analysis. Thirteen years after the Monroe Falls Dam was removed the old impoundment sediment continues to erode in some locations where the banks are nearly vertical. In the months following the Monroe Falls Dam removal, downstream, 114 cm of eroded impoundment sediment had accumulated vertically. The 2018 survey shows that most of the accumulated sediment had been transported further downstream and the channel returned to its pre-dam removal elevation. Following the LeFever Dam removal in 2013, the river channel incised into the impoundment sediment. By the fall of 2018, a profile in the former LeFever Dam impoundment shows that 55% of the impoundment sediment still remains. The river channel continues to erode and it is predicted to be 40 m wide based on how the river responded to the earlier Monroe Falls Dam removal. Twenty-five out of the twenty-seven channel bed sediment samples contain at least 50% gravel which reflects the higher stream energy post-dam removal. This study can be used to better understand the type and rate of geomorphic and sedimentological change following similar dam removals.