15 May 2008

High Snowpack- Always Good for Rafting?

The talk this season is of course the snowpack and water levels across the country. Global warming is obviously in full effect :) Most areas across the nation have experienced a good winter, which usually means that a good summer is to follow.

Good snow does not mean good river levels. Let me explain. We basically have two types of river-dependent factors to consider in the situation. Dam controlled rivers and natural flow rivers.

Earlier posts have talked about rivers across the nation changing over to dam controlled levels, in which certain river flows are guaranteed throughout the summer months. In general, good snow-pack and snow run-off are a good thing for dam controlled rivers. It means more water in the reservoir, and will continue to leave plenty of water flow throughout the coming years.

Natural flow rivers are a different story. Lets take a look at the Western U.S. as an example. The image here shows the current snow-pack levels across the various regions in the West. These numbers are a "percentage of normal", meaning that anything close to 100 is a very good thing, and anythin over 100 means higher-than-normal levels. Many locations that feed large rivers have over 100% snowpack for the season (still). But the weather still plays an important factor as to whether the snow will produce high, constant water levels or not.

Even with a good winter, if the weather heats up too fast, you run into flooding and fast run-off. So essentially, you would have a nice spring rafting season, followed by normal (or even below normal) water levels for the rest of the season. So it really still depends on mother nature and the transitional temperature from winter to spring to summer.

So remember that when the news reports a good winter, we still need to hold-on and see how the spring rolls out to accurately predict a good rafting season or not.

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