Design of Kirkman's Cove Lake Protection Measures

Kirkman's Cove Lake is a 65 ha (160 ac) reservoir located in Richardson County, Nebraska near the southeast corner of the state. The lake's 1,981 ha (4,896 ac) watershed is characterized by rolling terrain, steep slopes, highly credible soils, and predominantly agricultural land use. The stream network in the watershed is dense and experiencing severe streambank erosion. As a result, the lake is susceptible to high rates of sediment and nutrient loadings. These excessive loadings have resulted in rapid aging and eutrophication of the lake. To restore functional uses, improve water quality, and protect the lake against excessive loadings in the future, a comprehensive lake and watershed management plan was developed. The cornerstone of this plan was design of lake protection measures at the upper end of the lake to provide an effective, efficient means of reducing loadings to the lake. A multi-disciplinary design team of engineers and scientists developed the lake protection measures that consisted of: 1) a low-head earthen embankment across the main channel to the lake at the upper end of the lake, 2) a sediment/nutrient settling basin upstream of the embankment, and 3) wetlands along the channel's overbank areas. Construction of the lake protection measures was completed in the Spring of 1996. While too early to judge the level of success, preliminary results indicate that the system is functioning according to design objectives.