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1.5.1 Lake Owass® Lake Owasso is a 410-acre lake, with a 3,022-acre watershed. The Category I water body is a major recreational resource located in Roseville and Shoreview and is used for fishing, boating, water skiing, and swimming. A Ramsey County park on the north side of the lake provides public access and a swimming beach. The GLMWO Level Control Plan (1990) notes that problems on Lake Owasso include shoreline erosion, flooding of private property, and flood endangerment of low home during extreme runoff events. The GLMWO modified the lake outlet m .1`~'~ to reduce the probability of plugging and to lower flood elevations. No other flood prevention measures need to be taken. Lake Owasso also experiences problems with low water levels during periods of below normal precipitation. This is due to high infiltration losses to a buried bedrock valley (the Phalen Channel) that runs underneath the northeastern corner of the lake. Historically, the lake level was maintained through groundwater pumping. This practice stopped in 1989 when legislation placed lake level augmentation as the lowest priority for groundwater use, Summer water quality data has been collected nearly every year on Lake Owasso for at least two water quality parameters since 1973 (see Table 1-1). The summer averages were used to determine a long-term trend (improving, steady, or degrading) and a water quality action level. As survey level monitoring continues, the most recent summer averages will be compared to the lake's action level. This comparison and the long term trend will be used to determine whether management action is required. In 1999, the summer average transparency was 3.1 meters. The GLWMO set the transparency action level at 2.45 meters. 1.5.2 Lake Wabass® Lake Wabasso is a 52-acre lake located just north (downstream) of Lake Owasso. The lake is located in Shoreview and is an important recreational resource for the area. The Category I water body is used for fishing, boating, water skiing, and swimming. The GLWMO Level Control Plan (1990) noted that the outlet channel from Lake Wabasso tends to overflow, flooding adjacent backyards, but does not flood any homes. A hydraulic analysis completed for the lake shows that the 100-year flood event would raise the water level to the same elevation as the lowest home entry elevation. High waters on Lake Wabasso would also create a Grass Lake 1NM0 VI/atershed Management Plan 04/25/00 Draft \\NS2\WP\WP\23\62\645\plan\Grass Lake WMO plan.doc Page ~-7