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Mr. Mark Maloney April 21, 2008 Page 3 Task 11:Continued 2008 Watershed and In-Lake Monitoring Watershed runoff flow and water quality monitoring during storm events should continue in 2008 at 3 sites within the Lake Owasso watershed (discussed in more detail below). Additionally, the outlets of the major ponds/lakes should be observed at a minimum of bi-weekly to record if the water levels of the respective basins are above or below their outlets. Finally, in-lake water quality monitoring should be continued to be collected on a monthly basis from May 2008 -September 2008. See Attachment C for a map of the recommended. 2008 monitoring locations. Task 11a: Continue Watershed Runoff Flow and Water Quality Monitoring at the West Owasso Boulevard and County Road C Sites Expected Cost: $7,880 (By RWMWD) Task 11 a will include continued monitoring of watershed runoff flows and water quality at the West Owasso Boulevard site and at the County Road C site. However, at the County Road C site, we recommend that the monitoring station be moved to the upstream end of the pipe (southside of County Road C) to eliminate the backwater effects from Lake Owasso that occurred during 2007. Ramsey-Washington Metro Watershed District conducted the monitoring during 2007 and would continue to do the monitoring in 2008. Monitoring would occur from April 2008 -End of September 2008. Additional runoff monitoring at the 2 sites described above will allow for the validation and refinement of the P8 watershed model developed during 2007. Although the model runoff volumes were calibrated to the actual cumulative flow volumes at 3 different monitoring stations, infiltration rates were applied to all the ponds and wetlands throughout the watershed to reduce the runoff volumes. While the infiltration rates used to calibrate the model are very reasonable values, the total water load to Lake Owasso seems low for a watershed of its size. This could be the result of the additional storage that was available in the ponds and wetlands during much of the summer as a result of the extremely dry conditions during 2007. A lake-wide water balance model was also developed in 2007 to help verify that the runoff volumes estimated by the P8 model are correct. However, further investigation of the water balance using the lake's outlet rating curve and lake level information suggests that there were periods where the Lake Owasso outlet does not function as designed. The City of Shoreview Department of Public Works verified that ice build-up around the outlet structure limits flows from the lake during the winter months. Therefore, the water balance model alone can not be used to verify that the predicted watershed runoff volumes to Lake Owasso are correct. Thus, the additional inflow monitoring will be extremely useful. Task 11 b: Additional Runoff Flow and Water Quality Monitoring at Dale Street, just Downstream of the Composting Area Expected Cost: $3,940 (By RWMWD) Task l lb includes the installation of a watershed runoff flow and water quality monitoring site on the east side of Dale Street at the outflow point from the Central Park Pond East watershed. The equipment previously used at the Galtier Street site in 2007 could be installed at this location. Ramsey-Washington Metro Watershed District would do the monitoring at this site. Monitoring would occur from April 2008 -End of September 2008. This additional data will help quantify P:\Mpls\23 MN\62\2362946\WorkFiles\ProjectManagement\ForGLWMO_042.12008\Letter_Contract-Revised Scope_Apri121.doc April 2t, 2oos version