forgotten novel

[murphy white]

its about a village that's river have stopped running so about ten people went up the mountain to fix it, there was also some riddle about the dangers they would face and each one someone would head back, I think there was one danger about spiders and one where they have to crawl through tunnels. if anyone could tell me what book this was that would be very helpful
ps. I think the old lady that gave the riddle was named shiba don't know if that will help