My buds and I ran Foxton yesterday (Friday mid-afternoon); the highest we have ever run it. With muddy water and mobile strainers, and the fact that I only bumped into only a couple of rocks this time, I was really curious as to the CFS. So when I got home I went to the AW site to check the level:
South Platte, North Fork, Colorado, US
Buffalo Creek to South Platte (Foxton)
09/13/2013 2:13pm Pacific time (3:13 Mountain time)
? Sure seemed like a lot more to me. What's up?
Bailey's contribution to Waterton (a peak moving down the North Fork)
On 09/13/2013, the Bailey gage peaked at 521cfs at 08:00
On 09/13/2013, the Waterton gage peaked at 820cfs at 15:15
So it appears as though it took 9 hours and 15 minutes for the peak at Baily to arrive at Waterton at a distance of about 26 miles.
This would mean the flow was traveling on average of about 3 miles per hour: 26 miles / 9.25 hours = 2.81 miles per hour.
(I know this seems slow, especially when you are scouting the river, but there are a lot of flat sections to "slow the flow").
Decker's contribution to Waterton (a constant moving down the South Platte)
On 09/13/2013, the Trumbull gage (near Deckers) varied between 109cfs and 125 cfs from midnight to midnight.
So how does it add up?
At 15:15, 521cfs from Bailey and 125cfs from Deckers would make 646cfs.
With Waterton at 820cfs, subtract 646cfs from the two upstream gages, and that would mean the downstream tributaries such as Buffalo Creek and others on the North Fork and those on the South Platte contributed about 174cfs.
Conclusion with an assumption
Let's give 100 of that cfs to the North Branch, and that would put Foxton at about 600+cfs
mid-afternoon on 09/13/2013. Who knows what it was really running.
Note that at 15:15, the Bailey gage read 394cfs
So when you have a fast rise and fall on the river, and a lot of contributing tributaries between the gages, a little deeper analysis is needed before you go.
And support the AW 'cause they still provide great info and help protect our rivers!
Bailey (26 miles upstream of Waterton)
Gage Name: NORTH FORK SOUTH PLATTE RIVER AT BAILEY (PLABAICO)
Gage Location: Bailey
Gage URL: Detail Graph
Gage Name: SOUTH PLATTE RIVER AT SOUTH PLATTE (PLASPLCO)
Gage Location: 500 feet downstream from the confluence of the South and North forks of the South Platte River.
Gage URL: Detail Graph
Trumbull (16 miles upstream of Waterton)
Gage Name: SOUTH PLATTE RIVER BELOW BRUSH CREEK NEAR TRUMBULL, CO (USGS 06701900)
Gage Location: Location: 5 miles downstream of Cheesman reservoir
Gage URL: USGS Current Conditions for USGS 06701900 SO. PLATTE R. BLW BRUSH CR. NR TRUMBULL CO