Mount St Helens Survey 2024

On the summit at sunset

Sept 23, 2024

Eric Gilbertson

Summary of results: Elevation remains unchanged from last year at 8,321.1ft +/-0.1ft NGVD29

Last year I discovered that Mount St Helens has been slowly losing elevation at a very constant rate of 4 inches per year since 1989. This is based on an elevation from the USGS quads in 1989, four Lidar measurements between 2002-2018, and my own ground survey with differential GPS in 2023. The summit melts down to rock/dirt each summer, and the elevation loss is likely due to erosion. The steep north face of the summit drops into the crater rim and rocks are always tumbling down.

The route

I decided to return again this fall to re-measure the summit to see if it has changed again. I think it is important to measure St Helens in early fall when the erosion has already occurred over the summer and just before the autumn snows lock up the summit rocks in snow and ice. In 2023 I measured the summit in October, though there was a bit of snow to contend with to find the summit. This year I decided to measure in late September before the snows started.

It’s tough this time of year to get a permit to climb on a weekend. However, I was able to buy one for a Monday. I figured I could squeeze the climb in after work, like how I had in 2023.

Sunset views

In mid afternoon Monday I left Seattle and drove to the Climbers Bivouac. I was moving up the trail by 5:15pm. Many hikers were still descending, but by the time I popped out above treeline I had the mountain to myself. I made good time up the scree slopes as the sun set, and reached the summit just at the tail end of civil twilight around 7:45pm. I quickly identified the highest point with my sight level, and mounted the tripod on the summit. This year it was a solid rock about 1ft x 0.5ft.

I snapped a few pictures while there was still an orange ribbon of light on the horizon. Then I donned my down jacket and sat down to wait. I planned to do a 2-hour measurement to hopefully get errors down under 1 inch.

St Helens Elevation over time since 1989

I took a nap and enjoyed the view, then packed up by 10pm. I made good time hustling down, then drove home by 3am.

After processing the results I discovered the elevation of the summit has remained unchanged since last year. It is still 8,321.1ft +/- 0.1 ft. My pictures from each measurement session both show the same distinctive 1ft x 0.5ft rock on the top. I’m a little surprised the summit hasn’t eroded at the usual rate. One theory is that the erosion is mostly caused by the summit cornice falling off in the spring and ripping lots of rocks down with it. Perhaps the snow was more stable this spring.

I will hopefully be able to return annually to keep tracking this elevation over time.