The Ice Flood

The Ice Flood

Winter brings silence, cold, snow, and mystery. The mystery is apparent in how water behaves at low temperatures. Frozen water can take many forms: snow, ice, freezing fog. And snow and ice can take many forms and characters.

When the temperature is at or about freezing for several days, I like to go down to Lee Vining Creek and see what the creek ice is doing. It is simply amazing what freezing water will do as it flows downhill. The typical manifestation of creek ice is anchor ice, where the ice begins forming on the bottom of the channel where the water is moving slow enough to freeze. It also freezes into ice dams in various places, and slow water at the edge of the channel freezes as well.

This usually results in beautiful stair step pools flowing over ice dams, reminiscent of travertine formations in Havasupai Falls in the Grand Canyon, with beautiful blue water in between. When it gets really cold, and stays below freezing for a few days in a row, the ice builds up and builds up and the creek flows under it and over it and the ice soon fills the channel and sometimes more, filling high flow channels and nearby banks and low areas. This “ice flood” occupies the same areas that water occupies during a real flood, only the water is frozen. It floods willows and small islands, logs and trees. All in the channel is enveloped in ice. And it changes, as temperatures and flows change, flowing under the ice here, over the ice there, with numerous ice bridges and pools alternating in the various reaches.

This isn’t usually clear ice. It is white, like snow, formed from the spray of the rapids dashing against the rocks, formed with lots of air bubbles, formed from moving, not still water. If it hasn’t snowed yet, the creek will be a ribbon of white through the brown and grey bare ground and sagebrush, looking very out of place. Once it snows, the snow and the creek ice mingle in the view with little distinction between the two.

There is power in the ice. As it freezes to rocks on the bottom, the block of ice can be dislodged and pull the rocks free with it. I have only seen evidence of this once, but the power of the ice flood to move rocks and change the channel impressed me.

Fish survive the ice flood somehow. They find deep pools, however it is these pools that will freeze unless a plunge pool keeps the water moving enough. The swiftly flowing deeper sections of creek are the safest places to spend the winter, because the shallower areas freeze solid with ice dams and bridges and the anchor ice lifts the creek out of its bed. Winter is rough on the trout in Lee Vining Creek.

My first encounter with such ice was “frazil” ice in Yosemite Creek below Yosemite Falls when I was 12 years old. Yosemite Falls forms an ice cone at the bottom in the winter because the water freezes as it falls. The supercooled creek below the falls freezes as well. My sister and I tried to walk across the white, icy creek, since it looked like snow, and I soon found out that only the surface was frozen when my foot broke through and I got a really cold wet foot. I remember being impressed with this unusual situation that was entirely new to me.

I still get impressed, when I seek out Lee Vining Creek on the most bitterly cold days of the winter season--there is always something new to see. And now I always keep my feet dry.