I was bass fishing Lewisville Sunday morning and saw some kind of gillnet or floating seine tied across some timber in Hickory Creek/Veal Springs Branch. It was still there when I was headed home around 1pm. I didn't get that close but there looked to be a bunch of big carp and gar stuck in it (dead). It was probably 25 to 30 feet long and well away from shore. I looked online at TPWD and Texas Game Wardens but couldn't find anything on who to call and ask about it.

Any ideas?

Here's the link for the 5 game wardens that work Denton County. I would suggest calling any one of them.
Denton County Wardens

And you could call P.D. non emergency line.

If all else fails, call Operation Game Thief at 1-800-792-4263.

Josh Bulger is a cool dude and usually prompt to respond.
817-831-3128 office
214-491-7218 cell

Forgot to reply to this one. I left the last game warden a voicemail and never got a call back, but I'll put these numbers in my cell phone. Good to have them while out there on the water.

Just FYI; on the TPWD site there are lists (by county) of the local GWs with their cellular numbers. I keep the ones from the counties where I fish and hunt in my phone. They get transferred around; so you might want to refresh the list periodically. Also, in most counties the GWs are dispatched by the Sheriff's Office, in addition to their TPWD dispatch. It's a good idea to add the SO where you hunt and fish to your phone also. And if all else fails, there's always Operation Game Thief at 800/792-GAME (4263).