Thank you for the insight. Your comments got me thinking about the pond site I have in mind. If a dam was just thrown up at the location I have in mind I'd have about 8 ft of water depth. I had anticipated asking for somewhere around 8 feet of dirt to be excavated to get the depth I wanted. However that would only result in 8ft from the top of the dam and the ground level behind it. Why that's important is because I want to put in a siphon and as I understand it I want 4ft additional height behind the dam as is in the water. I would only be able to put the siphon 4ft deep in the water making it much less effective at removing the low quality water at the bottom of the pond. That's something I've got to figure out I guess.