[oelgnal1]

Be careful what you wish for, and I think that a "safe Herbicide" may be an oxymoron, at least from what I've seen over the years. Eco systems can be complex, and a band aid approach may be all you get for such a small body of water. Back in the 70's, I worked a few minutes away and would sometimes go at lunchtime for a few casts, usually during trout season. As I recall it's connected to the river and killies were in there. Keep in mind that when the weeds die, they will decay, and the herbicides don't always discriminate between the good and bad weeds even when you are told they do. I hope that you are right with your optimism because it was once pretty good years ago for the area.