bomber,

You need to go do your homework. When the river flows excessively, the flood gates open and thus goes your closed ecosystem. The fish get pushed around also, they may not go upstream, but when the gates open, they'll move downstream.

If you go back in time and look at the old historical pictures ( probably in Dougs Blog) you will see there has always been lots of water in this river. The water flow has been interrupted and controlled by the diversion into lakes Overholser and Hefner, but there has been aquatic life in this river way before statehood.

LA probably knows a little bit more about what is going on here than he's given credit. I know what his initials stand for, and if you think long and hard you will figure it out too, maybe.