This report is submitted in response to a request from the Illinois Department of Natural Resources (IDNR) for the Illinois Natural History Survey (INHS) to conduct a freshwater mussel survey in the North Fork Vermilion River (Wabash River drainage) in the vicinity of the Ellsworth Dam, Danville, Vermilion County, Illinois. IDNR proposes to remove this dam, and needs updated survey data prior to the removal per the requirements of Authorization item #7 in the Ellsworth Park Dam Removal Incidental Take Authorization. Freshwater mussels were collected by hand-‐picking and visual detection (e.g., trails, siphons, exposed shell) in the three zones (Impounded area, Construction zone, and Plunge pool). One live individual was found alive in the construction zone in three person hours, whereas 372 individuals representing ten species were found alive in the impounded area upstream of the construction in approximately 25 person-‐hours. A total of 46 individuals representing eight species were found alive in the plunge pool in 2.25 person-‐hours. All species collected are common inhabitants of central Illinois streams that are not listed as endangered or threatened at the state or federal level, and all live individuals were relocated to areas outside the predicted zone of influence.Prepared for Illinois Department of Natural Resources Office of Water Resourcesunpublishednot peer reviewedOpe
