There is an interesting trend in the Bureau of Reclamation’s 24-Month studies projecting future elevations of Lake Powell and Lake Mead: The Bureau projects recovering elevations in Lake Powell and continued deteriorating elevations in Lake Mead.
Lake Powell: A Rising Trend
Actual Lake Powell elevations in 2013 generally ran below levels forecasted by the Bureau in January 2013. January 2014 forecasts, which are generally unchanged from the December 2013 forecasts, were lower than the January 2013 forecasts. However, all three forecasts (January 2013, December 2013 and January 2014) project a turnaround in Lake Powell elevations in March 2014. The forecasted elevation in Lake Powell in the summer of 2014 exceeds the actual elevation of Lake Powell in the summer of 2013. Further, the forecasted elevation of Lake Powell in summer 2015 exceeds the forecasted elevation of Lake Powell in summer 2014.
A stock analyst would note that the elevation of Lake Powell will reach “higher highs” and “higher lows.” Looks like a recovery.
Lake Mead: A Declining Trend
Actual Lake Mead elevations in 2013 generally ran below levels forecasted by the Bureau in January 2013 until late last year. December 2013 forecasts had Lake Mead elevation falling below trigger for shortages by June 2015 but rebounding before January 2015. January 2014 forecasts are slightly below December 2013 forecasts. However, all three forecasts (January 2013, December 2013 and January 2014) project continued declines in Lake Mead elevation. The elevation in January 2014 is below the elevation in January 2013 and all forecasts project the elevation in January 2015 below the elevation in January 2014.
A stock analyst would note that the elevation of Lake Mead will reach “lower highs” and “lower lows.” Looks like a declining trend.
What Does History Show?
A look at the historical record of Lake Powell and Lake Mead elevations tells an interesting story. From 1964 (the first year of Lake Powell storage) through 2001, the January elevations of both lakes generally followed each other—rising together until the late 1980’s, falling together in the early to mid-1990s, and reaching a peak high in 2001 (the correlation between elevations was 0.92). Elevations started falling afterwards, although Lake Powell’s elevation started a recovery in 2006 while Lake Mead’s elevation continued declining. Since 2002, the January elevations of both lakes do not move as closely together (the correlation between elevations is small, 0.15).
Both the Bureau’s forecasts of future elevations and the recent historic record show that the dynamics of Lake Powell and Lake Mean elevations are different. Why?
Hydrowonk is looking into this. Once I figure it out, look for the analysis in JOW Corner in the Journal of Water (www.journalofwater.com).