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Eastern 117ashington Phase 11 Municipal Stormivaler Permit The maps should be standard USGS maps or GIS data sets derived from USGS base maps. 2. Any lake or reservoir with a contributing watershed area greater than 100 square miles. Reservoirs with outlet controls that are operated for varying discharges to the downstream reaches as for hydropower, flood control, irrigation, or drinking water supplies. Uncontrolled, flow-through impoundments are not exempt. 4. Streams that flow only during runoff -producing events. The runoff carried by the stream following the 2 -year, Type IA rainfall event must not discharge via surface flow to a non- exempt surface water. To be exempt, the stream may carry runoff during an average annual snowmelt event but must not have a period of baseflow during a year of normal precipitation. Hydrologic Modification of a Wetland A wetland receiving stormwater from a new development or redevelopment project can be considered for hydrologic modification if it is a Category 3 or Category 4 wetland according to the Eastern Washington Wetland Rating System and: There is good evidence that the natural hydrologic regime of the wetland can be restored by augmenting its water supply with excess stormwater runoff; or the wetland is under imminent threat exclusive of stormwater management and could receive greater protection if acquired for a stormwater management project rather than left in existing ownership; and: The runoff is from the same natural drainage basin; the wetland lies in the natural routing of the runoff; and the site plan allows runoff discharge at the natural location. Exceptions may be made for regional facilities planned by the local jurisdiction, but the wetland should receive water from sites in the same watershed. Hydrologic modification shall not be allowed if the wetland is classified as Category 1 or Category 2 according to the Eastern Washington Wetland Rating System unless the project proponent demonstrates that preferred methods of excess stormwater disposal (e.g., infiltration) are not possible at the site and that other options (e.g., evaporation) would result in more damage to the wetland by limiting inflow. Mitigation shall be required for the impact of hydrologic modification to a wetland. Appropriate measures include expansion, enhancement and/or preservation of a buffer around the wetland. Core Element #7: Operation and Maintenance Requirements Where structural BMPs are required, property owners shall operate and maintain the facilities in accordance with an Operation and Maintenance (O&M) plan that is prepared in accordance with the provisions in Chapters 5 and 6 of the Stormwater Management Manual for Eastern Washington (2004), or another technical stormwater manual approved by the Department. The O&M plan shall address all proposed stormwater facilities and BMPs, and identify the party (or Appendix 1- Minimum Technical Requirements Eastern Washington Phase II Municipal Stormwater Permit —August 1, 2014 Page 18