This paper gives details of the hydraulic investigation carried out for the proposed new bridge crossing over the Carrot River on Highway No. 23, near Carrot River, Saskatchewan. Geotechnical studies indicated that due to the very low shear strength of the highly plastic clay comprising the banks of the Carrot River, the river banks would not be capable of supporting the approach fills to the bridge. Highways Department engineers came up with the rather novel idea of placing a compacted clay fill or berm across the river at the bridge site in order to stabilize the banks. This introduced the problem of passing river flows through and over the berm. It was proposed that low flows should be carried through the berm by a culvert, and high flows should be passed over the berm by a spillway. Hence, the design envisaged a bridge over an earth fill and a spillway over a culvert, all at one site. A model study was considered essential because of the uncertain hydraulics and because a hydraulic failure could result in bridge failure.