Water Supplies in 2010 — Too Early to Tell

Spreck Rosekrans is an Economic Analyst at EDF.

 This morning, the Department of Water Resources released its December 1st water supply forecast predicting that State Water Project customers will receive only 5% of their contract entitlement in 2010.

It is worth noting, however, that these initial forecasts have historically been significantly increased later in the year. For example, the previous low initial forecast was 10%, made in 1993. After a wet winter, customers received 100% of their contract allocations.

Over the last 10 years, actual contract allocations have exceeded the December 1st forecast by an average 31%, or more than one million acre-feet of water. See below for a historical comparison of actual contract allocations to those predicted by the December 1st forecast for the period from 2000 through 2009.

As Director Lester Snow made very clear, this “preliminary” forecast is deliberately very conservative and is based on the assumption that 2010 will be very dry. Director Snow also pointed out that the amount of water that is ultimately delivered will depend on how the “Biological Opinions” (operational protections for endangered salmon and Delta smelt) are implemented. Let’s all hope for a wet winter this year — and better forecasts to come.