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potential is reduced. <br />e. Protect and improve natural resources within the watershed to prevent further <br />degradation. <br />22.2.2 Regulation <br />a. Rate Control. The proposed activity will not increase the peak stormwater <br />runoff rate from the site, under pre -development conditions, for anything less than <br />a 24-hour precipitation event with a return frequency of 1- or 2-, 10- and 100- <br />years. The applicant must comply with the requirements of the MPCA's General <br />Permit for Construction Activities. <br />b. Volume Control. Stormwater runoff volume retention shall be achieved onsite <br />in the amount equivalent to the runoff generated from one-half inch of runoff over <br />the impervious surfaces of the development or as specified under Section 8.0. <br />Volume control credits can be used to control up to one-half (0.5) inch of runoff <br />as described under Section 22.2.5. <br />c. Water Quality <br />Stormwater management must comply with the requirements of the MPCA's <br />General Permit for Construction Activities and guidelines set forth in total <br />maximum daily load studies and sustainable lake management plans. No direct <br />(untreated) discharges of stormwater to natural or improved waterbodies are <br />allowed. <br />d. Waste Disposal to Waters <br />Stormwater management must not result in the discharge of any regulated <br />substance, hazardous or biological waste, or petroleum product, whether treated <br />or untreated, to best management practice devices that may have a deleterious <br />effect upon water of the state (surface and groundwater), unless the discharge is in <br />compliance with Federal, State and local regulations. <br />22.2.3 Criteria. Stormwater management plans shall comply with the following criteria: <br />a. A hydrograph method based on sound hydrologic theory will be used to analyze <br />runoff for the design or analysis of flows and water levels. <br />b. Runoff rates for the proposed activities, development or redevelopment within <br />the watershed shall: <br />1. Not exceed existing runoff rates for the 1 or 2-year, 10-year and 100- <br />year critical duration storm events; <br />2. Not accelerate on or off -site water course erosion, downstream <br />nuisance, flooding or damage as demonstrated by the applicant; and <br />3. Runoff rates may be restricted to less than the existing rates when <br />necessary for the protection of public health, safety and general welfare. <br />