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-- - _ , Barr Engineering Company 4700 West 77th Street • Minneapolis, MN 55435-4803 Phone: 952-832-2600 • Fax: 952-832-2601 • www.barr.com An EEO Employer ~~~:~ _~".~ Minneapolis, MN • Hibbing, MN • Duluth, MN • Ann Arbor, MI • Jefferson City, MO April 21, 2008 Board of Managers Grass Lake Watershed Management Organization c/o Mark J. Maloney, P.E. Public Works Directory/City Engineer City of Shoreview 4600 Victoria Street North Shoreview, MN 55126 Re: Scope Expansion Agreement for Diagnostic-Feasibility Studies of Water Quality Problems and Potential Restorative Measures for Lake Owasso Dear Managers: This letter sets forth the Agreement between the Grass Lake Water Management Organization (GLWMO) and. Barr Engineering Company regarding proposed scope expansion for the Diagnostic- Feasibility studies of water quality problems and potential restorative measures for Lake Owasso. The additional scope of professional consulting services we will provide for your project includes completion of the tasks described below: x ane Scope of ervices During 2007, the Grass Lake Water Management Organization (GLWMO) retained Barr Engineering to perform a diagnostic feasibility for Lake Owasso. Much of the scope of work outlined as part the original diagnostic-feasibility study of Lake Owasso was completed during 2007 and early 2008. The completed work includes the development and review of a lake user survey, evaluation of in-lake water quality data and trends, macrophyte surveys, zooplankton and phytoplankton surveys, review of stormwater runoff monitoring data at three sites around the lake, development and calibration of a pollutant loading model to estimate watershed water and pollutant loads to Lake Owasso, a water balance model to verify runoff volumes and to estimate groundwater exchange to and from Lake Owasso, and an in-lake water quality model was developed to help evaluate the impacts of the various sources of phosphorus in the overall water quality of the lake. However, the summer of 2007 was an atypical climatic year, being one of the driest summers on record during June and July and one of the wettest late-summer periods on record. Although the pollutant loading model was calibrated to match actual monitoring data, there is some uncertainty about whether or not the calibration parameters selected for the 2007 calibration reflect typical climatic conditions. The uncertainty is partially the result of having limited number of acceptable monitoring events for calibration at the three runoff monitoring sites during 2007. P:AMpls\23 MN\62\2362946\WorkFiles\ProjectManagement\ForGLWMO_04212008\Letter_Contract-Revised Scope_Apri121.docApnlZ1,20C~ Version