(Photo credit: sektordua)

Not only is October 1 the start of a beautiful fall month, but today in Colorado we begin a bright new water year. Climatologists and hydrologists track surface water and accumulation of precipitation starting on October 1 each year. From the Colorado Water Trust’s newsroom:

Why does the Colorado Water Year begin on October 1st?  This explanation, crafted in 1985 by Nolan Doesken and Thomas McKee, is still as relevant as ever:

“In Colorado, the Water Year (October 1 through September 30) is the most appropriate period for monitoring climate.  This 12-month period is directly correlated with the state’s water storage—water usage cycle.  In October snow usually begins to accumulate in the high mountains.  As winter progresses, the snowpack normally continues to build up.  This snow is the frozen reservoir which supports the huge ski and winter recreation industry.  Eventually it supplies much of the water for human consumption, for extensive irrigation, for industry, and to satisfy long-standing steam flow compacts with neighboring states.  Irrigated agriculture still accounts for the vast majority of water used in Colorado.  Therefore, demand for water peaks during the summer and tapers off as temperatures drop, crops are harvested, and autumn arrives.  September marks an appropriate end to the water year.”

The water year is titled according to the calendar year in which it ends– yesterday we concluded Water Year 2013– and what a year it’s been. Take a look at precipitation data for Water Year 2013 from around the state or view data from previous water years. Not ready for the year to end? Cling to the next 30 days, October 31 marks the end of the irrigation year.