Predicting the Future-Steigerwald: Innovative & Cost-effective Approaches to Floodplain Monitoring

Year: 2022
Presenter/s: Sarah Kidd
Symposium Session: 2022 - 10 Complex, High-Risk, Climate-Resilient Floodplain Restoration
Topics covered: floodplain, lessons learned, modeling, monitoring, riparian, water quality, and wetlands


Understanding how our restoration actions change the landscape and benefit the ecology of a system are critical to both accounting for these efforts and providing feedback for adapting and improving our restoration actions. Monitoring of the Steigerwald Lake National Wildlife Refuge (Steigerwald) after implementation of the Steigerwald Reconnection Project must meet multiple objectives to ensure project success which includes monitoring to achieve regulatory compliance, inform adaptive management, and track project success. While these monitoring objectives are not unique, monitoring Steigerwald is a challenge due to both its size (1,000 acres) and the dynamic nature of the project. The project involves major changes to the landscape including removal of an elevated channel, Gibbons Creek, re-creating Gibbon’s creek historic channel and alluvial fan, and reconnecting the wetland floodplain to Gibbons Creek and the Columbia River, including multiple high flow channel connections. Across the site we will focus our monitoring on multiple restoration targets including 1) plant community changes in the floodplain, 2) water quality changes in the reconnected channel and Steigerwald Lake, 3) channel, alluvial fan, and floodplain geomorphic development, 4) and fish use. In this talk, we will provide a clear example of how pre and post-project monitoring was planned using testable hypotheses. Hypotheses were established during the design phase by using a paired hydraulic model (HEC-RAS), and ecological functions model (HEC- EFM) which integrated long-term reference site data into predicting post-restoration outcomes across the site. This approach provided a template of anticipated outcomes for identifying if proposed geomorphic, hydrologic, wetland plant community, and overall fish habitat objectives are being met post-restoration. The hypotheses will be tested though a combination of traditional ground surveys, unmanned aerial vehicle (UAV) data collection, and with the use of a flexible two-way PIT-tag array for fish detection. We will outline how the use of UAV data collection increases the efficiency and effectiveness of traditional floodplain and stream survey methods, which make full site surveying possible and affordable for such a large-scale restoration project. Additionally, we will provide an overview of the new more affordable, and reliable fish PIT-tag detection technology that will be installed and tested at Steigerwald and its reference site, providing continuous fish use data post-project construction. This overview of monitoring design, methods, and preliminary results for Steigerwald will provide the audience an example of new techniques that can be affordably deployed across their own restoration projects to aid ongoing restoration and adaptive management efforts.