This was a tour led by Boulder County Parks and Open Space of the Anne U. White Trail that had been destroyed by the September 2013 flood. The tour was free but the group size was limited, so one had to register in advance.
I arrived at the Four Mile Canyon Trailhead where seasonal rangers Sally and Francesca were waiting. Once the rest of the group showed (we were 9 people total), we loaded into a company van and drove up to the Anne. U. White Trailhead, passing lots of flood damage on the way.
Off on another adventure!
Roads were still being repaired.
Some houses had survived and were being rebuilt (with extra fortifications such as this giant wall)...
... while others were condemned.
We arrived at the trailhead (which is still closed to the public) and Sally gave us a bit of history.
Gilbert Fowler White (1911 - 2006) was an environmental geographer who specialized in floodplain management. In 1944, he married Anne Underwood, a local writer and open space advocate, who worked with him until her death in 1989. She donated 20 acres of land for the creation of this trail and so it bears her name.
The original trail was an easy 3.2 mile stroll out and back. It followed the Four Mile Canyon Creek through a narrow canyon packed with all sorts of trees and flowers. The trail was 70% destroyed by the flood. While the parking area has been rebuilt, construction on the trail isn't due to begin until next year.
The trailhead
Sally shares some photos...
... of the trailhead before and after.
Here is an aerial photo of the flooding of Four Mile Canyon Creek.
Sally then pulled out a couple of graphs she had downloaded from the U.S. Geological Survey. It turned out that the very woman who had drawn these maps was with us on our tour! She was able to give us even more information on them.
This chart shows the rainfall during one of the days of the 2013 storm. The white patch indicates the heaviest rainfall and was located very close to where we were standing now.
In 2010 there was a large fire nearby. This greatly increased the intensity of the flood due to the loss of so much organic matter, which could have otherwise helped soak up and slow down the water. The combination of this narrow canyon and less vegetation caused the trail to turn into a giant drainage.
The water levels went from 0.1 cubic feet per second to 65 cubic feet per second (think of one cubic foot as being the volume of a basketball). Then the meter was washed away, but estimates put the final volume at 1,000 cubic feet per second! That's a drastic change!
There had also been a flash flood back in 2011 that had washed away a car with people in it in the parking lot!
A chart of the 2010 fire damage
We set out into the canyon. We made our way whichever way we could.
This sign used to be next to the old trail.
Using the stream as our trail
There were several new side channels that had been created.
This was the highest section of the old trail... and also one of the only pieces that was spared.
Giant piles of debis lay scattered about.
A tire finds a new home in the middle of the giant wash.
Who me? The creek looks so innocent here!
We went for quite a while and eventually reached a good spot to turn around. Sally said this was the farthest she'd even taken a group before.
End of the trail for us
The water was covered with water striders.
Algal blooms are the result of increased or changed minerals (such as phosphorus) in the water, which is more the result of the fire instead of the flood.
Flowers slowly reclaim a piece of metal.
We loitered a short while then headed back the same way we had come.
Pushing through some thick vegetation
More large piles of debris
Back at the trailhead, we had the opportunity to inspect some more damage.
An old bike rack and trail sign
This house, which sits right next to the parking lot, was condemned. You can see it in the aerial photo earlier in this journal.
This house was a bit further back off the trail (also seen in the aerial photo) but it was unclear as to whether it was going to be rebuilt or not.
We piled into the van and were returned safely to our vehicles. The end of another sensational program!
More damage along the road
