You will hear me yammer away about how often I fish Boulder Creek and how dearly I love this particular body of water. I hope I don't get to sounding like a broken record. September and October are my favorite times to be on the creek. The water levels are at 25 cfs (low) clear and cold. The water will be at about 52-54 degrees in the morning and, on sunny days, rising to 56-58 degrees by late afternoon. If you find yourself up Boulder canyon in the morning you may have to use small midge or Blue Wing Olive mayflies (size 20/22). The cold nights keep the water temps low, the larger caddis dormant and cause the leaves and apples to drop. In the afternoon you will be able to get away with bigger bugs (size 16/14 caddis dries and size 18 nymph droppers).
If you happen to stumble onto a cluster of apples in a back eddy of Boulder Creek this Fall don't be scared to make them a stream side meal! I have no idea what breed these creek apples are, but they are sweet, delicious and usually only half bruised. (And they ain't road apples, I know that much...)