Where does the water come from?
How goes the flows?
Who plays frisbee golf?
The last question gets answered first... Outside of UC Santa Cruz students and Marinites... everybody in the freakin' Midwest (at-least according to our expatriates: Ryan D., Eric J., and J.P. (we'll get back to this).
As to the other questions... I'm glad you asked.
The North, Middle, and South Fork of the American River have distinct and unique drainages...
so, tells us more, old river guide and amateur hydrologist.....
The North Fork American is a completely natural river without dams, canals, or augmentations. With a fairly small drainage above 6,000 ft, where the majority of Sierra snows accumulate, the backside of Sugar Bowl Ski Resort is the headwaters of the class 4+ North Fork. When the Sierra's quit freezing and a 24-hour melt cycle develops (like it did this last Tuesday) the North Fork kicks in and flows freely. In great years, like 2006, the snowpack will squeeze runoff into the river until early June. This year, the early heat in March torched the winter snow pack, but these last few storms in April are now responsible for the flows that we have now. The North Fork should fall below 1,000 cfs soon. We had some great trips and we'll have at-least a couple more before the river becomes a creek.
The Middle Fork American is a different type of river system. The product of two major drainages, the Rubicon and Middle Fork, it also absorbs the water from the North Fork of the Middle Fork. The entire system drains the western bowls of Desolation Valley (just to the west of Lake Tahoe). Two large reservoirs (French Meadows and Hell Hole) store much of the run-off allowing nearly year-round, runnable flows. The drainages that supply the Rubicon and upper MIddle Fork are high and vast. Rafters and other river users continue to benefit from the system of storage and downstream delivery. This year looks good with solid and reliable flows to be delivered all summer.
The South Fork American drains the southwest corner of Desolation Valley and the slopes of the Sierra just to the west of Kirkwood and Sierra-At-Tahoe. Silver Lake, Union Valley, Loon Lake, and Ice House reservoirs all hold and control the flows into the South Fork American above 4,000 feet above sea level. With the large storage capacity in place on the South Fork, it takes two back-to-back dry years to severely limit runnable flows in the South Fork of the American. Last year was extra good and this year has proven to be better than OK. We now have guaranteed flows everyday of the summer except for one dry day a week (maybe the guides can play more frisbee golf).
Apparently the Mid-Westerners love frisbee F'n golf... they talk strategy, equipment, and courses like Tiger Woods must talk golf. I believe them to be sick.... but I also hate hacky sack and I truly enjoy throwing Grateful Dead CD's into the nearest garbage can... I know... that's sick, too.
Go raft a river & do a trip... enjoy what great flows we'll have this year... no, that's not sick: that's livin'!
Big Poppa posts are his own personal opinion; the rest of us like frisbee golf, hacky sack & the Dead!