Pond Dam Maintenance

We have had to do some heavy maintenance on the pond dam because of age and tree roots, and this spring we have begun in earnest to fight the trees back. We did a burn recently, and as soon as things have leafed out, we will be spraying herbicide to kill the brush and trees. Next spring we will burn again, and the plan is to do it every year so trees don't have a chance to start up again. The only problem in burning this spot is that the dam faces north, and it doesn't dry very well.