The effect of dams on river ecology and fish migration is a worldwide concern. FLOW-3D is used by professional designers and researchers to help solve the problems with under-utilization of fish passages. FLOW-3D lets you see inside fully three-dimensional and transient flow to examine important parameters like velocity, mixing, pressure, turbulence intensity and dissipation, and free surface profiles. Proposed designs can be compared to improve existing fish passages, modify designs to fit unique sites, and develop novel designs that fit the physiology and behavior of different fish species. Multiple flow conditions can be modeled for the same design to optimize peak and low-flow performance. FLOW-3D can also be used to model and design aeration systems for low-oxygen impounded waters and to mitigate unwanted air entrainment and total dissolved gas in reservoir discharges.