My pond called for 3:1 and 4:1 slopes however in the rush to finish we wound up with some underwater ledges that are pure drop offs. Not much I could do, we ended up running out of time with the equipment and the entire goal was to just get dirt out of the pond which was accomplished. Wish I had stumbled upon this thread again sooner because I did build one of my spawning beds pretty close to the drop off edge which means that bed will likely just tumble to the bottom as the edge erodes.