Hanging Lake: A Tufa Accident Worth the Permit

Hanging Lake should not exist where it does. The lake sits in a perched basin near the top of a side canyon off Glenwood Canyon, at an elevation that geology did not organize for lakes. What happened, several million years ago, was a fault: one block of the earth dropped while the surrounding terrain stayed in place, creating a depression that now collects water from springs in the canyon walls above it.

The springs deposit calcium carbonate as they flow. The calcium carbonate builds tufa, a porous limestone formation that constructs itself continuously, grain by grain. The tufa has built the natural dam that holds the lake. The lake is turquoise because the water is both clear and shallow enough for the light to bounce off the tufa formations below the surface. The waterfalls feeding it have built hanging gardens of moss and fern on the canyon walls. The whole formation is actively growing.

The National Natural Landmark designation came in nineteen seventy-three. The permit system controlling visitor numbers came much later, after foot traffic reached a point where people were walking on the tufa dam itself, which cracks under pressure and does not repair quickly. The formation that took geological time to build can be damaged in an afternoon.

The trail up from the Glenwood Canyon floor is one mile and roughly a thousand feet of elevation gain. It is steep. In summer, a thousand people a day used to arrive; the permit system now limits that to a manageable number. The lake does not know the difference. The tufa is still building.