The Bureau of Reclamation’s monthly forecast, out this morning (pdf), contains some very good news for Lake Mead and its water users in California, Nevada, and Arizona. But there is a huge caveat.
the good news
As it stood in early March, the snowpack in the Rockies was enough to send a big slug of extra water into Lake Powell during the spring-summer runoff. That would push Powell high enough to send a big slug of bonus water downstream, the result of operating rules intended to try to keep the reservoirs roughly in balance. If the forecast holds, Mead would rise 27 feet this year.
the huge caveat
Note those weasel words – “if the forecast holds”. It probably won’t. The Upper Basin’s version of the report (pdf) includes these words in big bold type:
It should be noted that since the March final forecast was issued on March 2, 2017, the Colorado Basin River Forecast Center Ensemble Streamflow Prediction indicates a decrease in the forecasted inflow. It is unlikely that the March final forecasted inflow will be sustained in the April final forecast. The April 24-Month Study projections are used to determine whether there is an adjustment to equalization or balancing under the Interim Guidelines governing Lake Powell releases for the remainder of water year 2017.
It’s not the March forecast that matters, it’s the April one. So the dry spring is taking a bite out of Lake Mead’s hope.
You: Note those weasel words – “if the forecast holds”. It probably won’t.
Me: Isn’t it nice to not be a journalist anymore? You can call a weasel a weasel.
John, while it seems like “good news, bad news” for Mead; in my opinion, it really isn’t–it is all good news, in my opinion. First, even though we may not have equalization releases in 2017, the probability for equalization releases in 2018 likely have gone up significantly. The runoff into Powell this year will be very, very good. Secondly, the side-inflows from tributaries between Glen Canyon Dam and Mead are currently 200% of average and have contributed something like two feet of elevation to Mead. I think the probability for shortage in 2018 is now very, very low. None of this takes into account any of the water supplies that will be left in Mead as a result of ICS or system conservation contributions. Finally, because of the wet winter uses are way down in the Lower Basin so far this year, again resulting in water being left in Mead. One would think this gives all of us a little bit of time to forge ahead with drought contingency planning and binational discussions.
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