I'm digging a pond in heavy clay soils. The pond was originally designed with a 3:1 slope in many areas, however I'm wondering if I can go steeper? What I'm more specifically trying to find out is if there is a slope where the clay soil will tend to just collapse and slide to the bottom of the pond? I've recently just read that bentonite for instance won't do well on a very steep slope and will slide to the bottom. Sorry I don't have very much more info on the clay that I have other than its mostly black and tan and it holds water very well. Probably the only good thing about my pond location.

The "Why" behind this is for multiple reasons. First is that my contractors screwed up on a few aspects of the pond and now it holds far less volume of water than originally planned. My pond only fills via rain water so I would like to try and rectify that. Second is that I'm looking at my shelfs and other features that I have for my spawning beds and just wondering if these vertical angles will eventually just collapse and spill all my pea gravel or if they will actually hold up for a good amount of time. Over time I would assume that things would degrade, however I'm hoping for the pond to have a good 25-30 year life span before it needs to be drained and given an overhaul.

I know I pop in and out of these forums sporadically. When I'm finished with this pond in hopefully less than 45-60 days I'll post up pics along with all of my costs that went into it.