The weather has been cold and pretty much squashed the Mother's Day Caddis Hatch. We need a few warm days to trigger it again, once we get that the evening dry fly fishing will blow up.
Fish stonelfy nymphs and caddis pupae (Prince nymph and Hare's Ear type nymphs) in the morning and mid day focusing on riffles and broken white water. There will be a mix of late blooming Salmon flies and Golden Stoneflies, so you can combine a large nymph with a small nymph during this time. When fish are rising to emerging Caddis, emerger patterns like X-Caddis, Corn Fed Caddis, and CDC emergers will be very effective. Later in the hatch, the Caddis will return to the water and lay eggs and a parachute Caddis will be effective, along with a traditional elk hair caddis. During periods of dirty water, anglers should use San Juan worms, flashy nymphs like Lightning Bugs, and black Stonefly nymphs. Later in May the PMD hatch will often occur mid-day and the Caddis will be hatching in the evening.
Strategies for Fishing the Yakima Canyon
Wade fishing can be challenging when the river is over 2,500 cfs so boating can be an advantage in higher flows. If you are wading, Euro style nymphing behind large boulders can be very effective. Dry dropper setups work well as the hatches begin mid morning on warmer days, on colder days a stonefly nymph/dropper combo is a great prospecting setup. As fish begin to feed on emerging caddis use a light rod with Caddis or PMD emerger patterns tied on a 5X tippet. Whenever possible try to target a single rising fish, and don't flock shoot.