I can try to get the number of the guy that handles that. You really dont want to just "go for it" as the Jasper City owns that and the police train there quite often. The launce fee is for the year and its a sticker for the boat. Its easy to spot if you dont have one.
At times there is a guy there at the ramp. If you are there on a weekend you should be in luck.
I caught a nice little bit of them yesterday after work. So barring more rain it should be fine.