A virtual gauge has been developed for the Lost based on the Brandywine gauge on the South Fork, South Branch Potomac and Cootes Store gauge on the North Fork Shenandoah all in cfs. The ranges are 355 - 1,500 cfs at Brandywine, 570 - 2,600 cfs at Cootes Store and 370 - 1,450 cfs for the Lost River virtual gauge. The painted bridge gauge (in feet) correlates to the virtual gauge (in cfs) as follows" 0' = 370 cfs; 1' = 452 cfs. The great Cacapon gauge is too far downstream to be at all useful for the Lost and the Moorefield gauge on the South Fork of the South Branch of the Potomac is best ignored for this run.
Because the river flows underground through here much of the year, it takes a lot of water for the Dry Gorge to run.
There is a painted gauge on the Route 55 bridge, west side abutment. A level of 1 to 3 feet is good, though it can be run down to zero. Construction of the Corridor H highway may ultimately change this gauge. Report observations here.