Thanks for the help, but I should have clarified.
I want the chute to be wide enough to: Lower water level in Pond 1 and collect fish in the chute. Seal access from chute to Pond 1, and then re-fill the chute to equalize with the water level in Pond 2. Open chute to Pond 2 to release the fish with no handling.
The system needs to function for controlling the water level, and being capable of also serving as a fish holding tank.
I am not worried about the minimal weeping of water due to the concrete (cinder) block wall construction. I am worried about the foundation footing being so weak that the walls will tip over.
I guess if I poured a solid concrete structure using forms, then the foundation might not matter if the entire construct was solid with rebar? A little tilting and shifting would not matter on that type of structure?
