Project operations that affect the impoundment of water can influence wetland communities and special-status species (i.e., populations on the shoreline of reservoirs), including:
- The timing and frequency of fluctuations in reservoir water surface levels can alter the structure and floristic composition of wetlands that are hydrologically connected (via surface or groundwater exchange) to project reservoirs.
- The dredging of sediment within project reservoirs or above project diversions can decrease the extent of wetlands within these areas.
- Recreational activities can degrade existing wetland resources by trampling along the margins of project reservoirs at key access points and high traffic areas (e.g., around boat launches or picnic areas).
- Water lever fluctuations can be of sufficient magnitude and duration to harm special-status plants by drowning or desiccation. See Section 8.2 for a discussion of shoreline management.
- Recreational activities associated with reservoirs may also lead to the introduction of non-native invasive aquatic plants. Boating is a particularly high risk, since boats are commonly transported between various water bodies, potentially transferring any aquatic organisms that may be attached to the boat.
In order to assess potential effects on wetlands, there are two general categories of approach: field-based evaluations of wetland “health” and remote-sensing of wetland “health” to assess the potential effects of the project through time. These approaches are described below.
