According to the CDEC website, they increased the flow from 510 CFS to 781 CFS (that's a 271 CFS increase!) between 12:30 and 12:45 P.M..  To me that is VERY irresponsible and dangerous.  I have monitored the stream's flow quite regularly for the last 7 or 8 years and I can't ever remember seeing such an increase in such a short amount of time (not due to the water spilling over the glory hole).  The only thing I can say is sometimes you can be forewarned of an increase in flow by seeing a lot of debris floating by.  But with such an increase in flow in such a short amount of time I can easily see how someone wading the stream could be put in a very precarious position.  If it were necessary to make such an increase in the flow, it should have been done at night when there would be no danger to wading anglers. 

Looks like a gaging station malfunction-instantaneous drop to 460?