06-25-08 Council Agenda - Laserfiche WebLink

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2.0 Lake Status Summary 2.1 Savage Lake 2.1.1 Lake and Watershed Characteristics 2.1.1.1 Description of Savage Lake Savage Lake is located just south of the intersection of Little. Canada Road and Interstate Highway 35E (I -35E) in Little Canada (Township 29, Range 22, Sections 6 &7), and is actually bisected by I -35E. Because it is divided by the highway, the eastern and western basins of the lake are connected by a pipe that flows from the west basin into the southwest corner of the eastern basin. Although called a lake, Savage Lake is actually a 27 -acre wetland, as it is not classified as lacustrine under the Cowardin system (Cowardin, 1979) used by the District to categorize waterbodies as lakes or wetlands. For this reason, it is considered a district- managed water body rather than a district - managed lake. It is also classified as Protected Public Water in the MDNR Public Waters Inventory (62- 8P/62- 147W). The West Savage Lake is 17.4 acres while East Savage Lake is 9.6 acres. The maximum depth of the western portion of Savage Lake is 5.9 feet, while in the eastern portion the maximum depth recorded is 5.7 feet. Approximate bathymetric contours have been created using . lake survey data gathered by the District in 2002 and can be seen in Figure 2 -1. The primary outlets of both basins are located on the respective eastern shores. The outlet from West Savage Lake is a 30 -inch pipe. The outlet of East Savage Lake was replaced in 2004 and is currently an 18 -inch RCP with a flared -end section and an overflow riser pipe. The new outlet established a NWL of 894.1 feet MSL. However, at this elevation, residents felt that water levels in Savage Lake were too low. In order to raise the NWL, permission from the MDNR and all adjacent property owners was obtained. In 2006, a wall was constructed in the riser of the outlet structure that raised the NWL to 895.1 feet MSL. Figure 2 -2 shows East and West Savage Lake as well as the primary outlet located in the east basin, The critical 100 -year flood elevation was determined to be 896.5 feet MSL during the development of the District Watershed Management Plan (Barr, 1997; Barr, 2006 [draft]) although with the increase in the NWL, the extent of the critical 100 -yr flood elevation has likely changed and additional modeling will be required to determine the new elevation. Figure 2 -3 shows the extent of the 100 -year critical flood for Savage Lake. Barr Engineering Company 5 P ;Mpls \23 MM62 \2362924\ MovedEromMpls P \2362924 \Oiher_Proj _Info \Report Info \Individual LSRs_11107\Savage \Savage Lake._Status,Report.doc [VI