On Oct 7-8 Gene Kiver and Bruce Bjornstad led two hikes in the Grand Coulee area.
On Saturday a group of ~30 hikers joined in a moderately difficult hike into the Castle Lake Basin, part of a 4-mile wide cataract complex that extends all the way to Dry Falls. The hike started out near Coulee City by following the Main Canal, which delivers all water from the Columbia Basin Irrigation Project into two siphons that cross Don Paul Draw at the head of Deep Lake. From here the water disappears before flowing two miles, underground, through a pair of tunnels to Trail Lake Coulee. The hike continued by crossing a berm of basalt boulders, dug out for the Main Canal, into the Castle Lake Basin. A descent to the floor of the basin was possible via two steel ladders that crossed the cataract above the Castle Lake plunge pool. From there hikers traversed out to a potholed bench to a spectacular view above Deep Lake Coulee.
The next day ~20 hikers joined a ~3 mile roundtrip hike to Giant Cave Arch, near Barker Canyon, along the west side of Upper Grand Coulee.
For anyone interested, both these hikes are featured in “On the Trail of the Ice Age Floods: The Northern Reaches” a geologic guidebook published by Bjornstad and Kiver in 2012.