This month’s US Bureau of Reclamation reservoir forecast model runs show the implications of the warm, dry spring, with a drop of 620,000 acre feet and six feet in elevation in the estimated end-of-year storage in Lake Powell, the major reservoir in the Upper Colorado River Basin. Here’s my long term forecast graph, updated with the latest estimates through the end of water year 2017:

Colorado River storage

Tony Davis had a good story earlier this week discussing this year’s big snowpack fail:

The low expected runoff does not mean a shortage in deliveries of Central Arizona Project water for 2017 — at least not yet. The U.S. Bureau of Reclamation has predicted a very low chance of a 2017 shortage but forecast a greater than 50 percent chance of a 2018 shortage.

Haven’t seen the latest model runs yet, but I assume that 2017 shortage number is going up.