Located in southwestern Manitoba, the Deloraine Dam spillway is a timber chute plunge pool structure at the end of its life. The spillway replacement design has been challenging due to a variety of unforeseen factors. Preliminary design planned that the new spillway be built over the alignment of the existing spillway with the existing riparian outlet used to manage flows during construction. An abandoned rail embankment approximately 300 m downstream of the spillway constricts flow and leads to significant variation in tailwater levels. A new stepped spillway with concrete stilling basin was designed, as stepped spillways are less sensitive to tailwater level variations. Between preliminary and final detailed design numerous obstacles were overcome. Management of flows during construction was decided to be provided by the existing spillway, requiring that the new spillway be designed in an alternate location. The new spillway had to be re-located once more following a geotechnical investigation that revealed high groundwater conditions in the body of the dam. Potential uplift pressures at the new location limited the allowable excavation into the existing ground at the toe of the dam; resulting in the existing ground elevations at the toe of the proposed dam at the new spillway being situated about 3m above the natural river channel, resulting in a unique “perched” basin. The flow at the base of the stepped spillway contained residual energy which needed to be dissipated, and a pool and riffle structure was selected to gently direct the flow to the existing channel.