Evolutionary Changes of Constructed Stream Restoration Techniques — The East Fork Case Study

The East Fork of the East Branch of the Black River, north of Lodi, Ohio, was experiencing increased bank erosion along portions of the river during moderate to high flows which was of concern to the Medina County Park District and other land owners along the river. Field investigations, maps and aerial photos indicated a moderately sinuous "C" type channel with gravel riffles and bars in some areas and highly modified or impacted sections in other areas. The 10,000 acre watershed drains mostly farm fields and undeveloped wooded areas with a small residential/commercial/industrial area on the north side of Lodi. A 1 to 2 year flow rate of 300 cfs resulted in a bankfull depth of about 4 feet, width of 50 to 60 feet and a velocity of 3–4 f/s, which was consistent with field observations of gravel bars and vegetation. The existing eroding bank heights at the upstream end averaged about 10' next to some farm fields and an access drive. These banks were eroding up to 10' per year and were threatening the farm fields, the access drive and several utility poles. The proposed restoration techniques included creating a lowered terraced vegetated shelf at bankful height next to the farm fields and two single wing rock structures along the access drive and utility line with a terraced shelf to deflect the stream energy away from the access drive. As is typically the case for any stream restoration project, this project was tested with flood flows within the first year after construction. But not just one flood, two 50-year storms and one 100-year storm flow came through in less than two months. The changes to the stream channel, structures, and vegetation left dramatic evidence to the effectiveness or ineffectiveness of the constructed restoration techniques.