Mackay Reservoir

Mackay Reservoir sits at about 6,100 feet on the Big Lost River just above the town of Mackay, under Borah Peak and the Lost River Range. It covers about 1,000 acres and holds stocked rainbows and kokanee, and it stores water for the farms of the Big Lost valley.

Rainbows cruise the shore after ice-off and in fall, when leeches, woolly buggers and chironomids work from a float tube or the bank. Kokanee fill the open water in summer. The reservoir is drawn down hard through the irrigation season, and the Big Lost River below the dam is a good tailwater of its own. Idaho's general rules apply: 6 trout.