I started using those numbers a long time ago when duck hunting. I noted the numbers when it was safe and went from there. Now that I am fly fishing I just use the same approach. When I fish a river and the conditions are good I note the readings. I have a real good idea what I will rind when I get there. My son and I started fishing the DuPage river. We had a couple of good days and I came home and noted the flow and level readings. I know that at 100-230 cfs it is safe and productive. At 400 cfs it is rough wading and there are big balls of weeds (like huge and heavy ) floating down the river. It is currently at 700 cfs, I am at home on the computer
. The database is searchable by date so you can go find the date you were there when the conditions were to your liking.