Bottom Bouncing Weighted Nymphs
Sometimes fish just don't want to come to the surface. In fact, some trout probably almost never eat at the surface and they are often the biggest fish in the stream. That's when you just have to go down and get them.
A great rig for getting your flies to the bottom is the bounce rig tied with a heavy weighted nymph and an unweighted or lighty-weighted nymph. There are a couple of ways to fish this effectively - either under an indicator or by tight-line nymphing and feeling for strikes.
Set up this rig by tying a length of tippet to the end of the leader with a blood knot and leaving the tag end extra long (6-10 inches). At the end of the tippet tie a very heavy nymph. I like large Hot-wire Prince Nymphs or Jumbo Copper Johns. This nymph will bounce along the bottom. Be ready to lose a few of these in the rocks. If you aren't losing a few then you probably aren't deep enough.
Then tie a small unweighted or lighty weighted nymph appropriate for your stream to the tag. You can do this twice and tie two nymphs on two tags where legal. This fly or flies will drift anywhere from a few inches to a foot or so above the bottom, depending on the length from the blood knot to the weighted nymph and will move rather freely with the current.
Be sure not to pass up the fast deep water. This is a great way to catch those almost unreachable fish that hold right in amongst the rocks near the bottom, even in spots where the surface currents look too swift.