Open Arches and Bridges and Streambed Simulation
Open arches generally are a good fish passage choice on high gradient streams with bedrock at the surface. Problem areas are inadequate footings and undersizing which can create a bedrock chute. (Baker and Votapka, 1990 and Browning, 1990)
Bridges are the preferred choice and are required to pass a 50 year flow with 3 feet of freeboard. Troubles with aggressive abutments can cause streambed scour and in rare cases cause chutes that are blockages.