 Moses Lake empties into Potholes Reservoir, which feeds irrigation canals to the south.Below O'Sullivan Dam several springs renew Crab Creek, which flows southwest, then west.Below the community of Smyrna, Crab Creek meanders across a two mile-wide canyon, bounded on the south by Saddle Mountains and on the north by the Royal Slope and containing portions of the Columbia National Wildlife Refuge, before emptying into the Columbia River.