Sunday, October 17, 2010

Lake Mead expected to hit historic low today. Is anyone paying attention?

John Fleck is winging his way to Lake Mead to observe an historic event expected to occur later today (10/17).  As I'm writing this the water level elevation in the reservoir is at 1083.2 ft.  As John points out, the lowest level the reservoir has ever seen (except when it was filling after first being constructed) was back in 1956, when it dropped to 1083.19, during what had been the historic drought of record for the river basin.

This is momentous for water geeks like John and I who love to observe the significance of historical events, but probably not so momentous for the average person.  The number that should have great significance, especially for anyone who relies on water from the Central Arizona Project, is 1075.  That is the elevation at which Arizona's share of Colorado River water will be reduced under the Shortage Sharing provisions adopted by the basin states a few years ago.  Many water managers in the Southwest think it's likely the reservoir will reach that level as early as next year.

When the level of 1075 ft is reached, Arizona (specifically the Central Arizona Project) will have it's water delivery reduced by approximately 300,000 acre-feet.  That's enough water to irrigate about 50,000 acres of alfalfa in central Arizona, or enough to provide municipal supplies to a city of almost 1.5 million people for a year.  Does this mean any cities in Arizona will have to cut back on their water deliveries.  No.  This means that the amount of excess water being taken by Arizona mostly to recharge aquifers in the central part of the state will be reduced.  Some farms will probably have to go back to pumping groundwater, but no municipal or industrial supplies will be affected until reductions become much larger - an unlikely occurrence in my lifetime.

But I can't help but wonder - what is the average Arizonan, who doesn't track these kinds of issues on a regular basis going to think when they hear Arizona's allocation from the Colorado River is being cut because of shortages on the river?  Will they drill deeper and learn that the water they use in their home will be unaffected?  Will they panic and start extraordinary conservation measures?  Or will they look to move somewhere else?

I don't know how much resource managers in Arizona are thinking about these questions or if they have developed strategies to get the right message out to the public, or even thought about what the right message is.  Do you tell people not to worry or do you say this a real threat to the continued viability of some communities in this state?  I'd like to know if there are answers to these questions, because I don't have them and I think they are needed.

1 comment:

Anonymous said...

Good article. It would seem that we need to deal directly with uncertainty such that water-use priorities and associated costs are treated objectively, not unlike what is used in the insurance industry. Think about it, all discussions about what-if scenarios like global warming (whether true or not), projected water levels, increased demand, etc., have no real meaningful basis without providing some risk-based context to decision-making: Without it we only have gossip and the capacity to admire this difficult problem.