California Water Flow Predictions, 2007 – the Fourth Quarter

In my most recent Blog post dated March 1, I used an analogy of a football game to explain our State’s “water year” which begins October 1 and ends May 31. Like a football game, these wet months are divided into four quarters. Most”points” are scored in the second quarter (December and January) and the third quarter (February and March), when the largest amount of precipitation usually occurs.

We have entered the final quarter of California’s water year (April and May). In most years we do not receive a significant amount of rain and snow from this point in the game forward, so many experts consider April 1 as a critical date for determining the outcome of our water year. This is also true for predicting water flows on rivers throughout the State. So what happened during the important part of the game, particularly during the month of March?

March was not as wet and cold as we had hoped it would be. We had two storms come through that left a few inches of rain and two to three feet of snow in the Sierras. The weather was mostly warm and sunny and as a result some of our snowpack melted sooner than it would have done had it been a cold, cloudy March.

Spring Run Rivers
Spring rivers have run well during the past few weeks which is earlier than normal. As a result of a low snowpack from the winter months and an early melt of some snow in March, our “spring time” runs will have a shorter season. Instead of running until the end of June or early July, these non-dam controlled rivers will flow well (but not high) through April and into May and June depending on the river. For more details on these rivers visit the river flows page.

Dam-controlled Rivers
Dam-controlled rivers are quite a different story. The season for these rivers will be long and consistent, thanks to the wet years of 2005 and 2006. Reservoirs are still full from two back to back wet years prior to 2007 and will have good flows all season long. For the past several weeks reservoir managers have been releasing water to make room for melting snows which means they have more water than needed for the coming season. For more details on these rivers visit the river flows page.

Even though we are in the fourth quarter and the game is not over yet, it is fair to say that 2007 is going to be a good year for California rafting but not an outstanding one. Flows will be shorter on non-dam controlled rivers and long and consistent on dam-controlled rivers. If April and May bring cooler and wetter weather than normal, future river flows and the rafting season will improve. If the fourth quarter continues to be warm and dry rivers and flows will remain about the same.

We will keep you posted on any changes that occur in the next several weeks that will effect the 2007 California rafting season. We look forward to seeing you on the river this year!