Development and Demonstration of an Improved Ranking Algorithm for Fish Passage through Culverts

Culverts have historically been designed to pass flood-stage rivers underneath transportation corridors. The design floods often range from the 5 year to the 50 year flood event, depending upon the type of corridor (Ohio Department of Transportation (ODOT), 2010). The low roughness and hydraulically efficient shape of a culvert allows for a significantly reduced cross-section through the culvert. The small cross-sectional area reduces construction and materials costs compared to bridge crossings. This flow constriction, while economically desirable, adversely affects the fluvial environment in the immediate and intermediate vicinity of the culvert (Wellman et al., 2000). One possible adverse outcome of culvert installation is reduced aquatic organism mobility (McKinley and Webb, 1956). All aquatic invertebrates require some level of in-stream mobility to travel between feeding and spawning sites, avoid predation, or adjust to seasonal stream variability (Yanes et al., 1995). Many culverts have been demonstrated to be fish passage barriers (Wilder and Barber, 2010). Along the North American coastlines, where large migratory fish species are present, significant gains in repopulation of endemic species have been achieved by replacing barrier culverts (Hotchkiss and Frei, 2007). Transportation managers in other regions are also rethinking culvert design to account for aquatic organism passage as many threatened or endangered species rely on fish hosts for their reproductive cycle (Maine Department of Transportation (DOT), 2007). Further Ohio Environmental Protection Agency (OEPA) is proposing new rules for stream mitigation (OEPA, 2011) leaving ODOT and other agencies to determine whether culverts will now need to be replaced and which should be replaced first. This proposal develops one method that ODOT may use to make such decisions and will result in (1) a list of culverts that may be passage barriers, (2) a ranked list of the barrier culverts based on stream miles that would be opened to migration upon removal, and (3) information about the swimming capacity of one important Ohio fish species. This project will develop and demonstrate an improved ranking algorithm for culvert fish passage. The results of this research are expected to reduce culvert replacement costs while increasing the impact of transportation funds on habitat restoration. Current algorithms have two limitations. First, they determine whether a culvert is a barrier based on the average water speed rather than the actual speed experienced by fish. Second, they are unable to predict passage of most Midwestern fish species. The proposed research addresses these issues while demonstrating the new algorithm on ODOT District 4 culverts. A three-dimensional computational fluid dynamics model will be coupled with existing one-dimensional models to accurately depict culvert flows. The new analysis algorithm and code will be made available online and will be demonstrated on 789 culverts in NE Ohio. A list of culverts that are predicted by this algorithm to be passage barriers will be created. This list will then be ranked in order of the number of stream miles that will be opened for migration upon culvert replacement. The object of this ranked list is to provide ODOT with information regarding the potential of receiving stream mitigation credits for culvert replacement. Of Ohio's 23 state designated endangered fish species, the swimming capabilities of 20 are unknown. Similarly, six federally endangered mollusks within Ohio require fish hosts for reproduction. Of the 16 host fish, the swimming capabilities of 13 are unknown. To begin addressing this shortcoming, the swimming capacity of one indicative species (rock bass) will be investigated. Thirty rock bass will be tested for their prolonged and burst swimming abilities. The results will be provided to ODOT, published in peer reviewed journal articles, presented at a national conference, and used to demonstrate the applicability of the approach to other state, regional, and national funding agencies.