FEMA Spillway Capacity & Extreme Flood Discharge Estimator Job Aid

This job aid provides step-by-step guidance for estimating the emergency spillway discharge capacity and probable maximum flood (PMF) inflow for dams when detailed design documents are unavailable. It is intended for use by dam safety professionals conducting screening-level risk assessments, particularly for the FEMA High Hazard Potential Dam (HHPD) program. The tool focuses on overflow spillways using weir equations and does not support riser-style or gate-controlled outlets. It is not intended for detailed design or regulatory compliance purposes.