River rafting in Washington state peaks during the month of July, in terms of the number of people getting out and white water rafting. However, every season, regardless of the depth of Washington state's snowpack, the peak flows happen much earlier.
I have been organizing, leading and rafting rivers in the state of Washington since 1975. I have seen every imaginable description of the snowpack. I have been rafting for so long in the Pacific Northwest, I remember when they changed (read: downgraded) the definition of 'average' snowpack in the Cascades because the snowpack was no longer accumulating to the extent it once did in earlier part of the 20th century.
I have also been guiding and rafting for long enough in the Northwest to report that, no matter what the snowpack is in February, or March, you would be presumptuous to state that the white water rafting season is doomed to bad water level conditions. This is because the spring could be colder than normal, drier than normal, wetter than normal or the snowpack could increase due to late snows, or the water content might increase due to cold spring rains, etcetera.
But, I am also aware that, as the recreational white water rafting industry in the state of Washington has matured, river rafting clients, who are averse to donning tight-fitting neoprene suits and layers upon layers of synthetic fabrics, continue to choose to raft when they are nearly guaranteed warmer weather and, hopefully, sunshine. Thus, the great majority of river rafting users journey over the mountains late in the spring, or early in the summer, sometime around the end of June, and what they are likely to find is low water.
That will definitely be the case in 2010.
If you are planning a river rafting trip in the state of Washington this season, and you are hoping for a memorable white water trip, I urge you to reserve your trip for May or early June. Beyond June, the best white water rafting trip will be the Wild & Scenic Sauk River which flows faithfully off the glaciers of Glacier Peak and should be navigable throughout the month of July. Which is another observation I have made over the decades.
A Seattle Times article today states that the snowpack on the western side of the Cascades is appreciably better than the easter side of the mountains.