Figure 1.

Schematic diagram and images of CO₂ deterrent deployed at the Royal Botanical Gardens fishway, Ontario, Canada. A submersible pump (A) moved wetland water through polyethylene pipe into an injection manifold (B). CO₂ gas was pumped from a liquid CO₂ dewar (C) into the injection manifold (B) where it mixed with ambient wetland water. CO₂ and water mixed throughout the manifold and hose delivery system, producing a stream of carbonated water. The mixing of CO₂ and water was assisted with two static mixers (D). The carbonated water was introduced to a fishway trap at four locations (E) spanning the full depth of the trap opening.