A Pre-construction Inventory and Wildlife Management Plan for a Flood Control Impoundment in Clark County, Wisconsin

Abstract

A pre-construction inventory of physical-chemical characteristics, plant communities, and animal taxa was conducted on the 655.9 ha Poplar River Watershed Area (PRWA) located in Clark County, Wisconsin, from May 1975 through May 1977. The inventory collected base information from the site of the proposed 117.8 ha PRWA flood control impoundment. Brick Creek, the major source of water for the proposed PRWA impoundment, is an intermittent stream; major stream discharge occurs in the spring and secondarily in the fall. The proposed impoundment will have a mean depth of 1.25 m, a mean annual flushing rate of 5.2/year, a 12 percent mean annual evaporation loss of mean stream inflow, and a drainage to impoundment ratio of 27:1. The impoundment will likely be eutrophic. A low siltation rate is indicated, but undecomposed vegetation, resulting from rooted aquatics, could be an important factor in the impoundment filling time. Waters in Brick Creek are characterized by moderately low specific conductance values, a circumneutral pH, and alkalinity and hardness values considered soft. A game fishery is precluded from Brick Creek and the proposed impoundment by temporary low dissolved oxygen concentrations and high water temperatures; winter fish-kills are expected in the impoundment. Nitrogen and phosphorus loading is sufficient for algal blooms to occur, and to support extensive stands of emergent vegetation. Chemical concentrations in Brick Creek were similar at the PRWA dam site and below the Owen dam, and in ground water. Coliform bacteria in Brick Creek could exceed maximum permissible counts for swimming beaches in the PRWA impoundment. Upland and aquatic vegetation was analyzed; a cover type map was constructed for the entire PRWA. Seventy taxa of aquatic macroinvertebrates were collected in stream riffles; a biotic index indicated "good" water quality. At least 19 species of fish occur in Brick Creek, and 9 species of herps on the PRWA. The redside dace (Clinostomus elongatus) and the bullfrog (Rana catesbieana) were present, and are classified as on "watch status" and "changing status," respectively, by the Wisconsin Endangered Species Committee. Use of the area by spring breeding waterfowl was minimal. Woodcock were common during spring 1976. A total of 107 species of birds and 29 species of mammals were known to be present. The arctic shrew (Sorex arcticus), an uncommon Wisconsin mammal, was the most abundant mammal in the small mammal census. Few species of waterfowl and shorebirds were present, and wetland associated mammals were poorly distributed because of meager amounts of surface water on the PRWA. A 10-year wildlife management plan, emphasizing waterfowl production, was developed.