Rusto,
I didn't realize your watershed was only 2 acres. That definitely makes the project easier.
I think Pat's idea is probably the easiest. How far do you have to move the water to get it past the edge of your pond berm?
10" x 20' culvert is only $103 at our Menards. 12" x 20' would pass even more water and is only $116.
I was looking at a similar project on my farm using a concrete drop structure and culvert.
I was going to build a little concrete form around the pipe inlet, and then go up to my emergency spillway elevation building a cinder block structure. For an extra $20 in cinder blocks and mortar you could make your drop inlet large enough to climb into if it ever managed to get clogged.
For your pond, you might have just a few inches of cinder blocks sticking up above your normal pool level. The turtles would probably think you built a sun deck just for them!
Good luck, and think about what you would like the next time you are going around your pond on the mower. I am sure you will come up with a good solution!
Best wishes,
Rod
