This gauge is located midway through the run and readings are somewhat dependent on operation of the diversion dam (it can be opened to flush gravel in the forebay during high flow events resulting in a lower reading than actual flow). Look at the Downstream Transducer on the Sultan bl. Diversion Dam gauge. Although a few creeks come in between the dam and this gauge, for the most part flows are regulated by Snohomish PUD. Minimum recreational whitewater flows are estimated to be 400-600 cfs with optimum flows estimated to be in the 700-1,000 cfs range, although individuals have reported great bigwater boating in the 2000 cfs range. These are rough estimates since there is no well documented flow data available from the rare occasions that this section has been paddled. Estimates are based on few observations and during changing conditions that make estimating flows at any given point in time or area difficult, but we have documented runs between 400 cfs to 2500 cfs and possibly higher. In December 2005, Snohomish PUD conducted an informal survey of whitewater boaters at flows of 650 cfs (view study report). Results of the survey indicate that 78% of boaters would have preferred a higher flow than the one provided for the reach below Culmback Dam.
A release usually only happens if good rains have filled the reservoir and then we get a big dump which pushes it over the top (it empties through a huge funnel tower in the reservoir at 1450'--view table reporting current reservoir elevation). This seems to happen once every several years Even if the reservoir is not spilling you can still run the river when pounding rains bring the river up (this happens when the Sky gets up above 30k). Under these conditions the run will be boney at the start and the level starts dropping immediately once the rain stops. You can also check flows on the Sultan below Powerplant gauge. The maximum capacity for the diversion tubes is 1300 cfs so you can subtract this value from the gauge reading to estimate the minimum flow coming down the river from upstream of the powerhouse. If this value is over 800 cfs you should have enough for a run. You can try calling the powerhouse 425-783-5549 (Try Barry Chrisman at extension 4 or his direct line which is 425-783-8804) for current information on reservoir status and project operations. For more information on the hydro project check their web site.