Court Creek Watershed (Knox County)

This watershed is located in an older glaciated region where streambeds cut through extremely erodible alluvial material. More than 50 percent of the sediment in the stream comes from bank erosion. Bank erosion in the treatment area was measured at 12 tons/linear foot. Vegetative stabilization measures such as willow posts, willow cuttings, and tree revetments were tried.

Dormant willow posts, 12 feet long, were planted at a moderately eroding site in early spring of 1986 and at a severly eroding site in December 1988. Posts were placed into excavated holes 6 feet deep, not pounded. Spacing was 4 feet by 4 feet in a diamond pattern. Survival rates at both sites were excellent and did not seem to be related to time of planting if planted materials were dormant. Plantings at both sites survived severe ice flows and flooding. At one site the landowner placed a 30-foot strip along the top of the bank as a conservation easement. Such easements are important where livestock graze. Prairie grasses and trees were planted. The rock structures seen at the waterline in the photo below are for fish habitat improvement.

At several moderately eroding sites (1 to 3 feet of bank erosion each year), tree revetments were installed. Sediment deposition behind the revetments will encourage the establishment of native riparian vegetation. At more severely eroding sites (more than 5 feet of bank erosion each year), dormant willow cuttings were planted behind tree revetments. The revetments will stabilize the slope until the cuttings are established and the root structure can hold the bank in place.