On May 18, 1980 the debris avalanche from Mount St. Helens covered 24 square miles of the upper Toutle river. This blocked tributaries of the river. The blocking of Toutle caused this lake to form (as well as Coldwater lake).
In other words, Castle lake is a barrier lake. An avalanche created a dam for the river during the St. Helens eruption.
Here I am at the Castle Lake Viewpoint Observation Site (above image). Tucked into the misty valley surrounded by volcanic bedrock is the sub-alpine lake. On a clear day from this spot, you can see Mount St. Helens, Castle Lake, and the landslide deposits from the eruption of Mount St. Helens. I took a short and dusty trail down to a good spot to view. I sat on a bench and looked at the green landscape. This has all been obliterated 37 years ago.
In the second image (below) we had driven further down to a dock where we had a gorgeous view of the clear water. The water is shallow and crystal clear which reveals quite a bit about the lake without much prior knowledge. The bottom of the lake is mostly different sized rocks, it’s not muddy, and the rocks are very jagged. Wood floats along the lake and is washed up at the shore. Tree remains scatter the circumference to this day.
It is marvelous to think we were on top of a debris avalanche. With the serenity that the stillness of the lake brought us, it’s hard to imagine that this was once debris moving hundreds of miles an hour. I rooted myself into the moment and thought of how this was the calm after the storm.
What we view now as beautiful landscapes may very well have once been pandemonium, grieving, terror, death, and radically different than what we see now.
Read my poem on life after the eruption to learn more about how life perseveres after catastrophic events.