In our area people call a bank rimmed when it has an immediate steep drop to several feet deep. I think it can be a 3:1 ratio and usually it's even steeper.
Mr. H's big pond had examples of both steep and gradual. It's also a pond which has had very little management other than regular mowing and occasional herbicides applied to the steeper banks where the mower can't safely reach.
This is how the "rimmed" bank looked last February, but the weeds are thicker now:
This side of the pond was left with the existing gradual slope. In this area Mr. H can run his Bushhog right up to the shoreline. I've never seen anything growing there other than the Bahia (?) that is the dominant grass. There are also not many more aquatic weeds in the shallow water in his pond, but I understand it will vary in each pond. (That is my faithful companion Flop Ear Dog)
I'm not trying to prove that steep banks aren't the best approach. A big factor influencing me now is the large number of ponds around here that are 5 feet below full pool. Most of them are steeply rimmed and in most cases it looks pretty ugly.
