The Situation
The Clear Creek Mitigation Bank project was started to address a series of environmental and functional challenges affecting the Clear Creek watershed. This area, which is part of the Clear Creek Greenbelt, is a heavily used recreational facility that has faced numerous issues including erosion, sedimentation and stream instability. The creek had become a nuisance due to frequent trail washouts, log jams, siltation at kayak launches, and erosion near buried utilities.
The site consists of approximately 772 acres of buffered stream corridor, which is vital habitat for wildlife such as bald eagles, bats, deer, mink, fish and mussels. The existing problems, combined with the need for ecological restoration and improved stream functionality, prompted the City of Coralville to invest in a comprehensive mitigation banking project. The project aimed to transform Clear Creek from a problematic feature to a valuable amenity, enhancing water quality, stream stability and recreational opportunities while generating revenue to support further city improvements and future mitigation efforts.
Our Solution
Eocene implemented a detailed and science-based approach to the project. The solution involved multiple phases, starting with an engineering and geomorphological study to assess and design the necessary interventions. Key actions included restoring approximately 8,803 linear feet of stream, including 6,565 feet of Clear Creek and 2,238 feet of Becky’s Creek, and adding 1,286 feet of oxbow construction.
The project employed various techniques to improve stream conditions and ecological health. These included:
- Floodplain reconnections.
- Creating meanders and oxbows.
- Increasing riparian buffers and stabilizing streambanks with natural materials such as root wads, logs and stone.
Specific interventions were designed to address stream instability caused by historic straightening and to enhance in-stream habitat diversity. Invasive species control was also incorporated, with manageable quantities allowing for long-term control.
Regulatory compliance was achieved through bird nest surveys to adhere to the Migratory Bird Treaty Act (MBTA) and other environmental regulations. This ensured minimal disruption and smooth progress throughout the project.