Sure there is a lot of biodegradable soaps out there. But most are harmful to lake life like fish and algae. So you need to find soap that are harmless to the species. Sierra Club posted a list a while ago and I found it very helpful. I tried googling for the page and I cannot find it.
While searching I came up with this page that I find troublesome.
http://www.nwf.org/News-and-Magazine...-Products.aspx
Looks like our quest for a bacteria free world will back fire.
Back to glycerin and other natural soaps?