43 CFR 423.37: Activities on iced waterbodies.

(a) You must not tow persons on skis, sleds, or other sliding devices with a motor vehicle or snowmobile, except that you may tow sleds designed to be towed behind snowmobiles if joined to the towing snowmobile with a rigid hitching mechanism, and you may tow disabled snowmobiles by any appropriate means.

(b) On iced-over Reclamation waterbodies, you must not ice skate, ice fish, ice sail, walk, ride, drive a vehicle, or otherwise move past buoys or barriers marking public access limits to, or come within 100 yards of, Reclamation structures including, but not limited to, dams, powerplants, pumping plants, spillways, water conveyance gates, intake structures, stilling basins, and outlet works.

(c) You must comply with all other posted restrictions.