I just installed rip rap in my larger pond to stop wind/wave action damage. Don't know what's available in your area but limestone is the most available and cheapest here. I got limestone that is the size of small to medium size boulders. I would say the bigger the better. I paid about $279.00 for 21 tons that filled a triaxle dump truck. It's actually the hauling that is most of your cost from what I hear.

Bill Cody tells me sometimes if a town or city is tearing out old sidewalks you can sometimes get them to haul it out to your place for free since they have to pay to get rid of it. Something to consider.

If pigs could fly bacon would be harder to come by and there would be a lot of damaged trees.