That’s a flood/drain valve meant to control water height. The giant pile of sticks and cattails behind it isn’t a beaver lodge, it’s two hours of some guy’s life, every single day, unplugging the 25 different drains that make this system run.
A few of us Castor nerds have been asked to help out, which shouldn’t be a big deal—looks like a trapezoidal fence/pipe arrangement will work fine. However, they’ve got tons of ‘invasive’ fish in these ponds (warm, slow, low DO, perfect for bass and crappie and bluegill) and want to keep them from getting out into the river. So we’ll do the opposite of the Snohomish leveler Mike designed, and add a small gauge screen to the pipe end to keep the fish out. Fish solved.
Finally, they want some method of mosquito abatement. And there’s the hook. Real innovation will be required here, since some mosquitoes can be laid in, hatched and back out of the water in 2 days. They’re really small, breed by the billions in these kinds of human-generated ponds, and are part of the reason that thousands of acres of water is getting sprayed with pesticides weekly down in the rice growing areas of California. Classic lose-lose scenario, and we hope to turn this around.