2002 Natural Resources Management

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Wetland Management To aid in the determination of Wetland Management strategies historic aerial photographs from 1940 and 1957 along with the National Wetland Inventory (NWI) map (Created by 1979 aerial photographs) were reviewed and compared to what was found in the field. It was determined that agricultural impacts altered the wetlands prior to the 1970's. Aerial photographs from 1940 and 1957 indicate that in general where feasible the wetlands were ditched and tiled to maximize the land for agricultural activities. Some historic ceramic tiles still exist in the wetland basins from this era and ditches can also still be observed. As land -use changed from agriculture to urban land -uses the ditches and the lines were not maintained and many of the wetlands re- established at the time of the NWI map development. Due to the partial drainage still occurring from the ditches and the lines a complete restoration was not realized. As the land -use changed to urban development the impacts to the wetlands were predominately the following: ■ cutting off drainage by roadways or development ■ rerouting drainage to or away from wetlands with the storm drainage system via culverts ■ sedimentation and nutrients entering wetland basins from adjacent land -use ■ filling or excavating for development or stormwater storage Over the years the alterations to wetland basins have resulted in reverting from native wetland species to disturbance - adapted exotic or aggressive species that invade the basin with disturbance. Goals for the wetlands within the study area should be to look for opportunities to restore the hydrology of basins and improve native vegetation. Hydrologic alterations along with disturbance have resulted in lower diversity in the native plant communities. Management objectives for wetlands should include maintaining or restoring native plant communities and diversity. City of Roseville 31 Parks Natural Resource Management