We’ve had a few inquiries about Big Lost River fishing conditions just below Mackay Dam. Right now flow out of the dam is not far below 400 cfs making for difficult and dangerous wading there. That’s about double normal flow for this date. It might be a while before run-off and water demand allow for better wading conditions.
We have not received much information on fishing the Big Lost River so far this year. Currently flow out of Mackay Dam is a bit higher than normal at around 350 cfs. Wading with caution is possible at this amount. Terrestrial insect patterns should work during daytime hours with trico spinner falls during morning hours and caddis evening activity filling out chances for action at other times.
The days of high water below Mackay Dam are gone until after the next winter of big snowfall. Flow just below the dam is where it usually is historically; around 500 cfs (about down to 0 cfs at Arco). This is a bit high for safe wading, but great for float-fishing. We have no reports on fishing this part of the river, but safe to say woolly bugger types, your favorite bead head nymphs (especially as a dropper/trailer with Woolly bugger types), and streamers will work for now. Let’s wait until water drops more before good dry fly fishing kicks in.
IDF&G is strongly considering a salvage regulation on the Big Lost River below Moore. This is because as flows out of Mackay Dam decrease fish will become trapped in downstream pools and perish. So rather than being wasted, salvage by legal means is being considered for the lower river. Go to the IDF&G web site for details on where this operation will be applied and for how long.
It’s worth the time to drive to Arco just to see the Big Lost River doing something it has not done in decades. That is flow through town (currently 383 cfs) and beyond. Flow out of Mackay Reservoir is currently 1300 cfs and has been at least as high for weeks, so it is no wonder that Arco is experiencing the river again. This high flow below Mackay Dam makes approaching the river tough and fishing slow.
Flow out of Mackay Dam is well over 300 cfs meaning wading immediately downstream should be done with some care. Early morning trico activity and late in the day caddis activity are providing action. With flow at the current level, such as San Juan worms or small woolly buggers can bring action.
Flow out of Mackay Dam was raised a little recently, but at slightly over 400 cfs wading is a bit difficult. Western green drakes are finished, but terrestrial insects are coming on. Fishing has been somewhat slow, but nymphing with PMD patterns is a good method for some success. The same for presenting patterns simulating aquatic or washed-in worms (SJ worm, medium sized woolly buggers). Flows will drop as irrigation demands diminish and calls for storage in the reservoir increase. Such should make for better wading conditions during the trico activity later this summer..