WALLA WALLA, Wash. – If your upcoming Columbus Day weekend plans include a road trip to visit family and friends on the opposite side of the lower Snake River, you may want to keep in mind that most U.S. Army Corps of Engineers dams are closed to cross-dam public vehicle traffic on federal holidays, unless otherwise announced. Open on Columbus Day-- Lower Granite Lock and Dam, near Pomeroy, Wash., will be open for public vehicle crossings on Columbus Day, Monday, Oct. 8 from 7 a.m. to 5 p.m.