Milwaukie History Railroads Ecosystem Industrial Development Works Program Administration Flooding Plan Restoration Spring Water Corridor Teens on the Trail Memories Childhood Memories Development Recreation & Restoration Courtesy of Milwaukie Historical Society Johnson Creek is known for its periodic flooding. Although there were efforts made in the past to control flooding, it seems that much of the resulting destruction stems from human use of the surrounding areas. Earlier flood mitigation attempts have even made the flooding worse in some areas. Throughout the 1970s, flooding was of short duration and fairly benign. The episodes left gardens with a new layer of silt but did not often flood basements and businesses. By the 1980s, however, the creek tended to flood during flash events and the ground stayed wet for weeks. Both development in Portland, and changes made to Johnson Creek over the years, have altered the creek's flooding pattern. Because of the flood mitigation work, low lying areas like the Lents neighborhood flood more often and more severely than previously experienced. Other areas now flood less often. An additional impact throughout the watershed but especially noticeable in Milwaukie is the filling in of wetlands. Before industrial and residential development, the average elevation of the floodplain along Johnson Creek Boulevard. Was three to five feet lower than it is now. Courtesy of Milwaukie Historical Society Much land was planted in crops during the summer months which helped retain floodwaters throughout the winter and spring. Now these areas are covered with houses and other buildings. The removal of wetlands has contributed to the frequency and severity of the flooding on Johnson Creek.