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vi INTRODUCTION The purpose of this document is to provide guidance to Local Governmental Units (LGUs) on what they must do if they wish to protect wetlands from storm water and snowmelt discharges to wetlands. It is not a rule, it provides technical guidance for implementation. at the local level. It is the intention of the work groups that the concepts contained in this document be incorporated with. planning and regulatory processes. Local Units of Government (LGUs) have asked the question: will the discharge of storm water to wetlands be prohibited? The answer is clearly no; wetlands require storm water for their existence. However, changes in the quantity or quality of storm water discharges can affect or even destroy wetland ability to support aquatic life and other sensitive functions. So what is the impact of our storm. water discharges to wetlands? There is a general consensus reached by the agencies involved in the development of this guidance that the type of wetland determines the wetland sensitivity. A plan and process that adequately addresses wetland sensitivity,~vill not allow stone water discharges that destroy the existing nature ofthe wetland, including its functions and values. The implementation of urban storm water management plans that minimize adverse impacts to wetlands and other waters can be achieved through the use of a comprehensive management approach. All elements of a storm water plan must consider a watershed or other large scale areas as opposed to piecemeal, project-by-project approaches. The complexity of the storm water runoff and wetlands issue is due to the numerous factors involved when storm water is discharged to wetlands. Those factors include: (1) the nature of the proposed change such as urbanization of a natural watershed; (2) changes in the quantity of storm water input to each wetland; (3)changes in the frequency and duration of storm water input; (4) changes in the quality (pollutant concentration and load) of the runoff; (5) the sensitivity of the particular wetland (e.g., a tamarack swamp is more sensitive to storm water input than. a reed canary grass or cattail marsh); (6) changes in functions and values of a particular wetland from its current state; (7) need for management practices to minimize the potential losses; and (8) selection of appropriate mitigation to compensate for lost wetland functions, values and uses. The Metropolitan Watershed Management Act and the enabling rules MR8410.0000 require, after January 1, 1995, that watershed and local plans address wetlands in the plans. Because of the new round of plan revisions that are currently being implemented, it is clear that LGUs have a major role to play in the protection of wetlands. The most reasonable approach is for LGUs to implement the watershed plans in their communities in accordance with a plan developed for the watershed and approved by appropriate state and federal agencies. This approach is mandated for the metropolitan area b}' the Metropolitan Watershed Management Act.