Tom,
Spent the weekend on a dozer clearing ground for another new pond...so couldn't respond until now.
Round bales: Here's what I do. Place them on top of the dam and unroll them sideways and down across the backside. Gravity will help move them along once you get it started unrolling. I like to go sideways because that way you get more coverage without having to pick it up and move it back on top again...don't get in front of it once it gets up a head of steam.
By spring it will be pretty well decayed, but if you want you can simply burn off the remaining. I like it because it adds humus to your soil as it decays and in most clay dams that's needed to get a good seedbed. It will sure stop erosion if you get the surfaces covered well.
Regarding your "spring"...as Dave mentioned, really look carefully at this. Since it is in your deep water, without question, I would cover it with 2 feet of well packed clay. If left uncovered, your spring very likely, when the pond fills, reverse direction and become a leak. Maybe it won't but since it is in the deep water, with the highest pressure, I would not take a chance on it and cover it up with good clay.
