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of I-694, in the City of Oakdale. This undeveloped area is comprised mainly of subwatershed OL-17, and VBWD acknowledges that this area may be landlocked. 4.2.8.2 Drainage Patterns and Stormwater. Issues The Lake Olson outlet, constructed in 1987 and located on Hidden Bay Road, controls the water elevation of both Lake Olson and Lake DeMontreville. As part of VBWD's Project 1007 construction, the old Lake Olson outlet, which consisted of a 72-inch pipe and headwall at 929.9, leading to a 30-inch pipe, was replaced with a new outlet which controls the water elevation at Elevation 928.35. The new outlet pipe is in approximately the same location as the old outlet pipe. The outlet now consists of 30-inch diameter pipes into and out of the control structure, which is a stop -log weir inside a four -foot diameter manhole. The stop logs can be removed to lower (drawdown) the Lakes Olson and DeMontreville water level in anticipation of heavy spring runoff events. In accordance with VBWD's DNR-approved Lake Olson operating plan, the lowest allowable drawdown is 926.5; at all other times of the year the control elevation is to be maintained at Elevation 928.35. Water from Lake Olson flows to Deer Pond, the outlet of which was also lowered, from approximately Elevation 924.0 to Elevation 918.0, as part of VBWD's Project 1007. The Deer Pond outflow combines with the Lake Jane/Hedges Pond outflow and discharges to Crombie Pond. The OHW of Lakes Olson and DeMontreville is 930.0. The highest recorded water level on Lakes Olson and DeMontreville was 930.4, in July, 1984, prior to construction of Project 1007. Prior to construction of the new outlet, lake elevations of 930 or higher were common. Since construction of the new outlet in 1987, the highest recorded water level was 929,0, in July, 1993, following months of above -normal precipitation. Figure 4-9, prepared by the DNR, shows historic lake levels from 1960 to the present. VBWD began measuring the Lake DeMontreville/Olson water levels in 1969. As of result of the new outlet construction, the 100-year flood level of the lakes was lowered from 931,9 to 931.5, One home was in the flood plain prior to construction of the new outlet. There are now no homes in the flood plain of Lakes Olson and DeMontreville. Low water was a problem in the past and both Lakes DeMontreville and Olson were reported to have dried up in the 1930's. Residents report that the channel from Lake DeMontreville to Lake Olson dried up in 1969. Winterkills of fish were noted by the DNR in 1947-48, 1950-51, and 1955-56. Pumping operations were conducted on Lake Olson from a Jordan well on the south side of the lake. Pumping brought higher water levels on both lakes until 1965 and improved winter conditions. The pump has not been used since it was shut off in 1965. The pump and pumphouse were not removed and are located next to the residence at 4719 Olson Lake Trail An intercommunity problem began in 1990 which involves the Cities of Oakdale and Lake Elmo regarding discharge from a pond in an Oakdale development to Lake Olson, located in Lake Elmo. The development is named Olson Lake Estates, and is located west of Olson Lake Trail (CSAH 13) and south of 50th Street North. Olson Lake Estates is located in watershed OL-18 (see Figure 2-3) and the area tributary to the development includes watersheds OL-1 through OL-12, OL-15, OL-16 and OL-18. The immediate tributary area to the large pond in Olson Lake Estates (DNR #82477W) is 84 acres. Including the upstream watershed, the total drainage area to the pond is 486 acres. Approximately half of the tributary watershed is located west of I-694. The intended watershed outlet was to be -a storm sewer from the pond to the culvert under Olson Lake Trail and then overland about 300 feet to Lake Olson. 23\82\045\SEC4.RPT\KMH 23 DRAFT: June 23, 1994