Soooooo - I just called a local manufacturer of hardware cloth/metal screen/etc. Talked with a super nice young man who was trying to help me find options, prices, amounts.
A 4' x 100' roll of #8 mesh (not stainless) is $727.00.
Arrrgggghhh!
I have to decide if I want to postpone the pond for another year so I can save up to buy this.
Or do I put in another layer of heavy duty underlayment to discourage the chipmunks? (So far, knock on wood, they haven't chewed anywhere in the front yard pond and I know they live in the hill with the waterfall filter.