2002 Draft Natural Resources Management

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Wetland Management To aid in the determination of Wetiand 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 h�storic ceramic tiles still exist in the wetland basins from this era and ditches can also still be observed. As land-use changed from a�m-iculture to urban land-uses the ditches and tile lines were not maintained and rnany of the wetlands re-established at the time of the NWI map developrnent. Due to the partial drainage still occuzxing from the ditches and tile lines a completc restoration was not realized. As the land-use chanbed to urban development the impacts to Ehe wetlands were predominately the following: ■ cutting off draina�e by roadways or development ■ rerouting drainage ta or away from wetlands with the storm drainage system via culverts = sedimentation and nutrients entering wetland basins frotn adjacent land-use ■ filling or excavatin� for development or stortnwater storage Over the years the alterations to weCland basins have resulted in reverting from native wetland species to disturbance-adapted exotic or aggressive species that invade the basin with distarbance. Goals for the wetlands within the study area should be to look for opportunities to restore the hydroloby of basins and improve native vegetation. Hydrologic alterations alon� �vith disturbance have resulted in lower diversity in the native plant comrzzunities. Management objectives for wetlands should include maintaining or restorina native plant communities and diversity. City of Roseville 29 Parks Nat��ral Resoa�rce Mnnagerne�it