Wednesday, March 31st, marks the closure of the entirety of Silver Creek and the Big Wood River (the South Fork Boise River also closes on March 31st). These waters will open again on Saturday, May 29th. Until then, anglers will have to concentrate their efforts on other fisheries.
The Big Lost River near Mackay remains open to fishing all year. This tailwater fishery can be incredibly productive during April if river flows remain stable and low enough for easy wading. As of right now, flows coming out of Mackay Reservoir are at approximately 110 CFS, which allows anglers easy access to all stretches of the river. Flows much higher than 300 CFS make wading and crossing the river channel difficult, essentially limiting fishing access. Given the lower snowpack in the Big Lost drainage, it’s likely that flows on the river will remain wadable throughout the month of April.
April will see significant spawning activity on the Big Lost, so anglers should be careful when wading and avoid spawning redds. Look for oval-shaped depressions of clean gravel along the river bottom (the female trout scours the riverbed with her tail to loosen gravel) and avoid fish that are actively spawning; let the trout do their thing!
Midge activity will be present on the Big Lost throughout the month, but the main hatch activity will be the BWO (or Baetis). These bugs hatch in great numbers on most afternoons, and anglers should be prepared to fish several stages of the BWO – nymph, emerger, and dun. The BWO ranges in size from 18-22 and is grey-olive in color.
Olive Pheasant Tails, olive Rainbow Warriors, and green Copper Johns are great choices when nymphing. Small Pat’s Rubber Legs and Prince nymphs are also productive, representing small stonefly nymphs present in the river. Of course, tiny zebra midges in black, red, olive, and brown are essentials on the Big Lost.
When fishing to rising trout, anglers should carry RS2s, Quigley or Last Chance Cripples, and Sparkle Flag Duns to imitate the emergent and adult BWOs. Small Parachute Adams in size 18 – 22 will also fool plenty of trout.
Trail Creek Road is closed, so the only route to the Big Lost for valley anglers is through Picabo. Stop by the fly shop to pick up everything you need for a day on the Big Lost! We’re stocked with rods, reels, lines, leaders, tippet, and flies, and our grill can make you a wonderful lunch to take on the river. We’ve also got plenty of snacks, coolers, and ice-cold drinks in our store.
Happy Fishing Everyone!