the river is under TPWD authority and it is legal to discharge a firearm there, as long your bullets do not cross any property line. basically, if you're practicing safe shooting, you will not be shooting past/over the riverbank anyway, so there's nothing to worry about.
as long as the county does not regulate the discharge of firearms, you're good to go. i promise you, it's perfectly legal. you can't do it in harris county; but you can for sure in brazos and montgomery county.
i'd only go out there with a very small group though.
You can ride in the back of my truck
I'm easy.....
How about a meet at my house? Free condoms at the door!
Or how about a meet at Cigar Cigar, sugar land town center? They have a poker room in the back and a patio llounge. And they sell cigars.
EDIT: Oh wait we're actually shooting at this meet lol