Metropolitan Southern California’s use of Colorado River water on track to be the lowest this year since the 1950s

MWD 2019 water use forecast. Weird graph to read – it’s the forecast made at each point during the year. So back in January, the USBR was expecting MWD to take nearly 850kaf. That’s dropped to 551kaf.

The Metropolitan Water District of Southern California’s deliveries of Colorado River water this year are currently forecast at 550,518 acre feet, and depending on conditions over the two-and-a-half months of the year could drop as low as 506,000 acre feet, according to forecast data from the Bureau of Reclamation and what folks at MWD told me today.

That is the lowest draw on the river by coastal Southern California since the 1950s. Since 1964, MWD has taken, on average, more than a million acre feet of water per year from the Colorado River.

The reasons are twofold. First, a big Sierra snowpack (the fifth largest since 1950) meant a larger allocation via the California State Water Project – a 75 percent allocation (which is really bigger than it sounds – it’s a big allocation). Second, Met’s become much more nimble in conserving water and juggling the various supplies within its service territory.

I keep a dataset of the annual use by Met and other major Lower Colorado River Basin water users that goes back to 1964 (the year the Bureau began formally documenting use as part of the requirements of the Supreme Court’s decision in the case of Arizona v. California – the data’s here if you want to paw through it for yourself). 551kaf would be the lowest in that entire time period, so I wrote to a friend at Met asking them to dive into their older data. Previous low years:

  • 1958: 538kaf
  • 1956: 479kaf

So at the current official forecast of 550,518 acre feet, this would be Met’s lowest use since 1958. But with a current target within Met of 506kaf, this could be the lowest use of Colorado River water by metropolitan Southern California since 1956.

Either way, that’s before I was born.

 

 

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