The Big Game of Predicting California Water Flows for 2007

Posted March 1, 2007 by Gregg Armstrong, Co-Founder

Hi. I am Gregg Armstrong, co-owner and founder of All-Outdoors California Whitewater Rafting. One of my many responsibilities over the years has been to watch California’s rainfall and snow pack totals to determine and predict what the rafting season will be like before it arrives.

One thing is for sure when it comes to California weather and snowpack totals, no two years are ever the same. We have spent more than 45 years watching weather patterns and storm totals during the fall, winter, and spring, trying to determine what the coming rafting season will be like, and we have yet to say; “this was just like the winter of ___, so the rafting season will be ____”. Watching weather patterns in the “wet” season to determine river flows during the “dry” season in California is like watching a sporting event, you show up, pay attention, enjoy the game, and wait until the end to find out what happens!

The game of California precipitation totals lasts eight months and is called the “water year”. It begins October 1 and ends June 1. Each “quarter” is two months long. The first quarter (October and November), and the fourth quarter (April and May) are not the most important because the amount of precipitation for these periods of time in usually low. The middle quarters are the most important. December and January make up the second quarter and February and March the third. Most of the rain and snow that arrive in California come during these four months. Let’s review the game as it has played out so far:

First Quarter:
California experienced a relatively dry October and November compared to “normal”, which is a 50-year average for this period of time. Because these two months do not play a key role in California’s water totals for the year the score at this point in the game is not that important.

Second Quarter:
There were four storms that came into California during the month of December which left the state with about 70% of normal precipitation by the first of the year. January was a different story all together and was one of the driest on record in California. Most areas only received a trace of rain and very little snow. California was not in good of shape water wise on the final day of January. When the halftime show began, we were only at 40% of normal.

Third Quarter:
This is the most crucial of all quarters. The months of February and March represent the final build up of snowpack and rain in California. Because they come in the second half, the final outcome of the game is often a reflection of what happens in these two important months. Historically speaking, California has often been way behind in the first and second quarters, but has come back during this third quarter to make up yardage and eventually win the game (California wins when it ends up at 100% or more compared to the 50-year average). I can remember this occurring in 1986 when we were on the verge of a drought by mid March. Late in the month a huge series of wet, cold storms rolled in from the north and dumped large amounts of rain with nearly 11 feet of snow falling in a short eight day period to create one of the wettest water years in California history. During the past twenty years there have been several wet months in February and March that have left California with an excess of water as we head into the dryer months of the year.

The third quarter in 2007 is shaping up to be one of those comeback quarters. Since February 9, several storms have come in that added large amounts of rain and snow to the Golden State. During this past week alone, we have gained almost 30% when it comes to average totals for this time of year. We are now at 70% of normal and more storms are predicted to arrive next week. If this wet pattern continues, through the month of March, we should be near normal by the time we enter the fourth quarter on April 1.

What does all this mean for the 2007 rafting season?
It’s too early to make final predictions because the game is only in the third quarter, but thanks to the past two weeks of wet weather, it is safe to say that the season will be good even if the scoreboard remains as it is. When precipitation levels are at 70% on March 1, non dam-controlled rivers that flow only when snow is melting will do well most of spring. These rivers include the Merced, Kaweah, North Stanislaus, Cal-Salmon, and North Fork of the American. Dam-controlled rivers are in great shape and will run very well through the 2007 rafting season. This is largely due to the fact that we are coming off two back to back heavy winters that occurred in 2005 and 2006 and left reservoirs at near full capacity coming into this year. The rains we have received this winter have topped off these reservoirs and many are already releasing water to make room to catch snowmelt when it comes in the spring time. Dam-controlled rivers include the South and Middle Forks of the American, the Tuolumne River, and Cherry Creek.

We will continue to monitor the weather and its impact on the rain and snow totals in California. Look for an update every two weeks and feel free to contact us at anytime with any questions you might have in regard to flows for the 2007 season. We are thankful for a good third quarter so far and look forward to seeing what the next several weeks bring to California!


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