Cost Analysis of Alternative Culvert Installation Practices in Minnesota

Various factors associated with conventional culvert design, including shallow water, perched inlets, and high-flow velocities, can cause difficulties for migrating fish and affect their genetic diversity and longterm survival. Conventional culvert design has traditionally been based on hydraulic conveyance, safety, and cost. Recently, some alternative culvert designs have been developed to facilitate salmon migration on the West Coast of the United States. These alternative designs focus on matching the natural dimensions and characteristics of the stream channel through the culvert. The intended purpose of these newer designs is to provide unimpeded passage of aquatic life, reduce maintenance costs, and improve erosion control. Currently, some of these new designs are being implemented in Minnesota, mostly when fish passage is a consideration. There are concerns about the additional costs associated with these alternative designs as well as whether they are really needed at some road crossings. The objectives of this research were to summarize statewide fish-passage concerns related to culvert road crossings on public waters and to perform a cost comparison between the conventional and the alternative culvert designs.