I have the same size pond and I am dealing with the same issues. In my case I sank four stacks of pallets in 4'water, each weighed down with 6 cinderblocks. Get more than one person if you do this - they don't want to stay down. These are for the minnows to lay eggs on, and for smaller fish to hide. I have only done this one month ago, but the fish are definitely concentrating around them. I also bought several 4-5' kiddie pools at a baby store, filled them with 6" of pea gravel and also sank them in 4" water. My water is really murky, so I can't tell you if the Bluegill are using them or not. The rest of my bottom is mud, so the would be worse off without it. I sectioned off portions of the pond that are for fish, and I keep the swimmers away from them.
As for raising the level, that is my dad's idea that I am fighting, but I respect my dad a lot and it's difficult to do that. He plugged up my overflow pipe to increase the water level and several things happened:
1. Water backed up on my neighbor's property, but he is OK with that.
2. We get flash floods 1 - 2/yr, so when the water comes, there is lot of it. So the best I can tell, there was at least 6" flowing over my spillway because I found my boat way down on my other neighbor's property.
3. Water started seeping around my overflow pipes with quite a trickle. My dad wants to put concrete around the pipes on the pond side, but I am not convinced that it will help.
I know that he will fix the pipes if he really screws things up, but I don't know how many fish I lost.
