The trail upstream from Black Rock is lovely (wear shoes that can get wet and dry out--you muck through springs)and the opportunity to experience remote Mill Creek and Deer Creek canyons is awesome (looks so close to Chico and Red Bluff on the map--don't be fooled!). It's the driving that's gnarly. The road to Black Rock from the north side of Ishi Wilderness (Ponderosa Way going south from Hwy 36) is very long and slow (2+ hours from 36)with large rocks and ample tire-popping potential for regular street tires. Our party's Toyota truck and Subaru Forester did fine, but we were REALLY worried that the Subaru would get a flat. Then, we threw caution to the wind and proceeded south instead of backtracking; there's a good gravel road out of Mill Creek canyon, and you come to an intersection that heads north on the good road towards Hwy 32, or south on the slooooow road towards Cohasset. We were told that the road to 32 would be snowbound...mid-April...we said nahhh...4.5 miles later we were halted by snow. So after that 9 mile detour we took the rocky road down into Deer Creek and back out of the canyon to Cohasset. Beautiful, spectacular, verrry slooow, and you might want to bring a chainsaw--we came to a tree that had fallen and was propped up by other trees diagonally across te road, and the only reason the Toyota truck (with rack) could get under is that somebody before us had notched out a hair's-breadth clearance at exactly the place where the rack had to squeeze under. Otherwise, t would have been 45 miles back to Red Bluff! All in all, the day trip was about 6+ hours of driving for 3 hours of hiking, but it was exciting and well worth it for the experience (but maybe not if anything had gone seriously awry).