Dike Fields and Macrohabitats of the Lower Missouri River

This project summarizes broad, two-dimensional spatial availability of fish habitat across the Lower Missouri River (from its confluence with the Big Sioux River near Sioux City, Iowa downstream to its confluence with the Mississippi River near St. Louis, Missouri). One of the main objectives of the project was to delineate and categorize dike fields, which we define as areas directly downstream from man-made, earthen dike structures. Dike fields represent potential refuge habitats from the fast-flowing navigation channel maintained for boat traffic along the river thalweg. Dike fields were drawn within the boundaries of the main channel of the Missouri River given bankfull conditions and with reference to existing dike structures as defined using spatial polyline datasets maintained by USGS (https://doi.org/10.5066/F7FF3R9D) and the US Army Corps of Engineers (USACE; available upon request). Additionally, as a second objective, we delineated continuous macrohabitats (inside bends, outside bends, and channel crossovers), representing areas with unique hydraulic attributes that could also influence habitat usage by fish. Continuous macrohabitats were delineated based on current standard operating procedures for USACE fish sampling field crews (Welker and Drobish, 2016), with guidance from field crew leaders.