Updated 7/24/2019. The flows of the Big Thompson through the park have been dropping. Your best chance at catching a trophy brown in Moraine Park is fishing a nymph rig down in those undercut banks. Drop a Purple San Juan Worm, Iron Sally (size 18), Rainbow Warrior (size 16), or a black Zebra Midge (size 18). Above the meadow, the river is still moving pretty quickly. Fishing a dry dropper rig with a terrestrial pattern, like a Black/Tan Chubby Chernobyl (size 14), or yellow stimulator on the surface and a BD Pheasant tail (size 18) or a black Copper John (size 18) below.