Poorly designed and failing road/stream crossings directly impact Michigan Rivers and streams. Failing road/stream crossings can impact water quality and aquatic communities and lead to excessive erosion, increased sedimentation and increased water velocities. Perched culverts or culverts with diameters less than the width of the stream can act as a barrier to fish and other aquatic organism movement. Road/stream crossings can alter essential stream processes and ultimately impact river ecosystem health.
There exists a need for a standardized assessment of road crossings to help evaluate the current impacts to fish passage, aquatic and wildlife habitat in Michigan. Road/stream crossings have historically been overlooked, on a global scale, and investigators and resource managers are now just beginning to understand the potential impacts they can pose on aquatic systems. Several studies have shown that fish passage barriers commonly occur when road crossings are culverted rather than bridged (e.g., Thompson and Rahel 1998, Warren and Pardew 1998). Fish passage through these structures is difficult due to a variety of factors (e.g., perched, high flow velocities, insufficient water depths, etc.). However, culverts at road crossings are common due to their relatively low costs (compared to bridge crossings). Detailed assessments documenting occurrences where roads negatively impact streams are necessary to improve connectivity, and while regional and large-scale databases exist for other barrier types (e.g., dams), comprehensive data sets detailing potential ecological impacts of road stream crossings are less common. The Conservation Resource Alliance (www.rivercare.org) and Huron Pines (www.huronpines.org) have established a comprehensive data base for road/stream crossings in Northern Michigan (Lower Peninsula) and is made publicly available at www.northernmichiganstreams.org. Trout Unlimited seeks to assist in expanding this effort in Michigan through identifying and filling data gaps.
The establishment of standardized databases will increase data availability and can aid barrier remediation decisions and efforts (Januchowski-Hartley et al. 2013). Identifying problematic road stream crossings and assessing them for potential restoration opportunities is a focus of Trout Unlimited so to help increase habitat connectivity and overall health in coldwater watersheds throughout Michigan.
Road/Stream Crossing Examples
Recently completed projects by Trout Unlimited’s Great Lakes Program.
