HOW DO LOW-HEAD DAMS AFFECT SEDIMENT DEPOSITION AND TOXICITY IN INDIAN CREEK IN SOUTHERN INDIANA?

Primarily built between the late 17^th century through the early 20^th century, the original purpose for most low-head dams no longer exists, resulting in ecological barriers and safety concerns. Removing obsolete dams improves water quality, revitalizes fish and wildlife populations, increases public recreation opportunities and human safety, and is a boost to local economies. However, dam removals can release sediments trapped behind the dam that can be toxic. Therefore, research prior to dam removal is necessary to protect aquatic life from potential exposure to released toxic sediments and to ensure the stability of the downstream river system. The focus of this study was sediment accumulation and potential toxicity in the reservoirs behind two low-head dams in the Indian Creek watershed of southern Indiana. These dams are being targeted for removal. Six sediment samples were collected from each dam using a bottom dredge at five transects: three in the reservoir and one each upstream and downstream of the dams. The sediment samples were tested for the presence or absence of total organic carbons, polychlorinated biphenyls, pesticides, and heavy metals—toxins that can adversely impact aquatic life. This research supports conservation efforts in a biodiverse watershed by providing information for consideration prior to removal of two low-head dams.