Case Study

Fish Surveys – Dam Removal Projects

Aquatic fish surveys were provided for a Dam Removal Project by LWC with IDNR. Surveys were conducted both before and after project construction. Zero (0) hornyhead chub were captured before dam removal compared with 31 after dam removal. This species inhabits relatively moderate-gradient or steeper streams which have riffles and pools. One central stoneroller was captured after dam removal. This is an important finding since this species only inhabits moderate-gradient or steeper streams. The proportion of blackstripe topminnow, a species which inhabits quiet pools, wetlands and backwater areas increased 233%. Central Mudminnow also was found after dam removal. This species, like the topminnow, inhabits quiet pools and backwater wetland areas which expanded after construction. The proportion of largemouth bass increased almost 600%. The proportion of bluegills dropped 90%, indicative of a conversion from pool habitat before dam removal into free-flowing stream habitat after dam removal. Another new, desirable species at the site was Johnny darter which were not found before dam removal. In all, 8 new fish species were found using the restored site upstream of the dam after dam removal. Seven (7) of these fish species were not found at any locations (upstream or downstream of the dam) prior to dam removal. The total number of fish species increased 55% to 17.