Riding the Crest of a San Juan River Summer Monsoon Flood

Last week I got to run the San Juan River in Utah for four days with friends. The drive up was spectacular with bursts of rain falling everywhere along the way. In the drive from Mexican Hat to Bluff, every side stream was full of red, silty runoff. Then, on Friday, August 24, we arrived at the put-in and witnessed the crest of flood coming down the San Juan. A dozen basketballs were on their way to the Powell Reservoir. Unfortunately, my camera was in the shop and I did not get to take any photo's. But my friend Toni took a few pictures of the fantastic scenery found along the river.

Here is the hydrograph for the river during our run. The date is labeled on the bottom. The pink line traces the level of the river in cubic feet per second (cfs) at a point along the river near Mexican Hat. So the pink line includes discharge from Chinle Creek, which was flooding very large when we floated by. The green line marks the level of the river near Farmington and you can see that it is straight-lined through the whole event, meaning that most of the flood water came into the river downstream from there. The red line is the Four Corners gauge and some floodwater had entered the river by then. The big pink spike shows the input from drainages between Four Corners and Mexican Hat. We rafted the river until August 27, when the pink line approaches the pre-flood stage. We rode the crest of a wave!

All photo's by Toni Kaus. A view of the Comb Ridge monocline as it upturns strata. Note the obvious river terrace cut through the upturned strata. This terrace lies about 150 feet above the modern channel, meaning that it likely has cut down that much in about 100,000 years.

Meanders of the San Juan downstream near the mouth of Chinle Wash. The Mule Ear, an upturned spike of Wingate Sandstone is visible in the upper left.

View of Comb Wash in flood beneath the Comb Ridge monocline