There are good hatches of midges daily on the Big lost and on warmer afternoons the blue wing olives show up. Before and after the hatch try a tungsten zebra midge in size 16-18. A small #8 golden stone is also a good choice if there is nothing going on the surface.
Some good dry midge patterns to try are light gray pulsating midge emergers, Harrop’s CDC Spent Midge (gray) and small red marco midges. For blue wing patterns make sure you have both emergers and duns. Last week we had good luck also on a Harrop blue wing olive nymph suspended under a #16 parachute adams.
The midges started around 11 am with a few Blue wing olives in the early afternoon. We’ll see more and more blue wings as the March weather warms things up.
The Big Lost is one of the streams that has a winter stream season so it is open beginning December 1st (yesterday) through the end of April 09′ The regulation is catch and release fishing for rainbows.
The Idaho Fish and Game regs list the streams open to winter fishing by region.
Flow out of Mackay Dam is only 60 cfs. This may be the winter month flow, and it concentrates fish in deeper holes. But just below the dam fish are responding well to dry midge and small soft hackle patterns. Use sizes 18-22 for both. Action slows on the river as one goes downstream.
If you don’t mind unsettled weather, the river below Mackay Dam is a place for some great action because of BWO and midge activity. Flows out of the dam are just above 50 cfs. Low flows like this concentrates fish in deeper runs & holes, so active fish are easy to find. But they are up for a tough go all winter, so treat ’em gently.