Bull Creek Restoration and Stabilization
Lake County Stormwater Management Commission (LCSMC)
Basin Program Funds:
Eroding downstream ravine reaches of Bull Creek and resulting sedimentation in Illinois Beach State Park where hydrology changes and pollutants are degrading high quality wetlands.
Riparian and aquatic habitat degradation is significant along the downstream Bull Creek ravine due to down cutting and widening of the stream channel. Hydrologic change and erosion are the most significant threats to the watershed’s natural resources. Urban runoff associated with land development is the cause of this impairment. Most of the headwater reaches have been ditched or are conveyed through storm sewers to increase conveyance capacity and flow.
Resident concern over the severe erosion along the channel in the project reach prompted the formation of the not-for-profit Bull Creek Stakeholders Association (BCSA) in 1999. BCSA has led the endeavor to resolve problems within Bull Creek by organizing a series of outreach/education events and sponsoring the Bull Creek Restoration and Stabilization Project. These efforts have resulted in the involvement of local and regional agencies, units of government and conservation organizations in outreach events such as a watershed bus tour, a conservation easement informational meeting, a riparian landowners workshop, an upcoming stream-monitoring workshop, and in coordinating and supporting the Bull Creek restoration project.
A summary of project activities include:
- Educate and involve riparian landowners and other watershed residents to make a long-term commitment to improving Bull Creek and the Dead River watershed.
- Secure a conservation easement on 10 privately owned lots along the stream corridor.
- Remove non-native and invasive plant species and provide more sunlight to deep-rooted native plants used to stabilize the streambanks by selectively removing invasive woody species along 1,500 feet of steam corridor.
- Channel invert grade stabilization for 970feet of streambed including an exposed sanitary sewer using 9 artificial riffles. Dissipation of energy for high stream flows by excavating floodplain terrace along 5 inside bends.
- Stabilize streambank along 970 feet of ravine stream channel.
The Bull Creek ravine setting required the use of vegetated geogrid lifts and access was somewhat difficult, making the project more expensive than stream restoration projects on lower gradient streams. The Best management Practices (BMP’s) used at Bull Creek are not unique, but the combination of practices used is unique to ravine projects in this area. Newberry riffles were used to stabilize the streambed (grade control) so that the streambank practices would not be undermined by the streambed downcutting. The inclusion of the floodplain terrace practice on the inside bends in this project design recreates a floodplain where the natural floodplain had been cut off from the channel due to the incision of the channel over time. This is the first time this practice has been applied in a ravine system. The floodplain terrace not only replicates natural channel morphology, but also dissipates some of the flow energy as floodwater spills out of the channel onto the recreated floodplain thereby taking pressure off of the opposite outside bend where erosion susceptibility is high.
The overall project design includes a combination of practices that provide a permanent (or at least long-term) solution to the problem, require little maintenance and offer some redundancy. While deep-rooted native plants are the practice of choice for stabilizing streambanks, it was determined that plants alone would not stand up to the flashy flow rates and volume through this reach. On the outside bends that are highly susceptible to erosion, harder practices are used in combination with the plants. For instance the stone toe protection practice, while minimized, is used opposite the floodplain terraces along the outside bends that have suffered the greatest erosion. These practices used in combination serve as a safety factor to reduce the risk of project failure over time.
Monitoring and maintenance (M&M) will be a key component for gauging long-term project success. SMC has developed a draft plan for the project reach to guide both homeowners and SMC in future maintenance efforts. It is anticipated that the most intensive maintenance needs will be related to plantings during the first 3 years of the project. The Contractor’s plant installer is responsible for maintaining the planted areas for the first 2 growing seasons and for replacing any plants that die. SMC will monitor the condition of the practices and the general condition of the stream reach on an annual basis. Permanent station markers are being installed for this purpose, and rebar will be placed at cross-sections where there are pinch points and those high-risk outside bends to measure any erosion that may occur over time. Pre-project conditions have been documented by photo and video and post-construction is being documented likewise for future reference.
Contact: Ms. Patricia Werner, 847-918-5269