Where I fish (the Columbia and Willamette mostly) the carp eat a lot of clams, aquatic worms and nymphs, so a San Juan worm fish well. Tricky to fish as you just have to leave it there for the fish to find and figure out when they eat, but they eat the worm well out here.

Typical forage on a sand flat:


I fish the worm n sand flats and go with soft hackles in gravel and cobble. Again, match the local forage. I caught this beast on a size 12 soft hackle.