I realize that the lake may not have quite reached the peak, but it’s very close, but since I’m heading out to Lake Powell and thus off the grid for the next week or so, I just wanted put this year’s rising lake levels in historical context. And yes, there’s still one more day in July, so the numbers reported below could still change slightly…
Bottom line—at just a hair over 53 feet, this year turns out to be the 5th highest springtime rise in the post-1964 era. Pretty remarkable! Here are the top 5:
1973 – 58.24 feet (that year the rise continued all the way to Dec 31, though mostly done by mid-Sept…)
1979 – 57.84 feet
1993 – 56.10 feet
2005 – 53.28 feet
2019 – 53.09 feet (through 7-30)
Still an outside chance of catching 2005, but you get the idea…
But it’s not just about surface elevation rise. 2019 has been remarkable or unique in several other ways, notably how late in the spring/summer season it happened. This year saw the highest post-1965 June rise ever at 27.17 feet, and third highest July rise at 9.78 feet. Combined, this year saw the second highest rise from June 1 onward.
Highest post-1965 June rise:
2019 – 27.17 feet
2011 – 25.85 feet
1968 – 24.76 feet
1995 – 21.37 feet
No other post-1965 year even reached 20 feet in June.
Highest post-1965 July rise:
1995 – 13.31 feet
2011 – 11.92 feet
2019 – 9.78 feet
1973 – 7.69 feet
Combined June-July:
2011 – 37.77 feet
2019 – 36.95 feet
1995 – 34.68 feet
The overall duration of the rise has been 111 days since April 10. That's above average (which is 100 days), but not phenomenal...and that's due to the very late start in the runoff season... Overall, this year has tracked remarkably close to what happened in 2005. The lake started very low that year (at 3555), rose about 53 feet between April 8 and July 12, and added a net volume increase similar to this year, just under 5 MAF...
In terms of net increase to the volume of the lake, 2019 was nearly as impressive as the surface rise, and that’s a more important statistic. Overall, it’s the 6th highest net volume increase post-1964, at 4.94 MAF. The top years:
1979 – 7.48 MAF
1995 – 6.78 MAF
1993 – 6.67 MAF
1973 – 6.31 MAF
2011 – 5.91 MAF
2019 – 4.94 MAF
1997 - 4.64 MAF
2005 - 4.61 MAF
Put that in perspective—the average net volume increase since 1965 has been 2.75 MAF (which by the way, is LOWER than the 2.89 MAF average since 2005, which puts recent years in a more accurate context in terms of the common perception that drought is just a recent phenomenon). Of course, that net increase is a measure of inflow less outflow… a better measure of how “big” a year this has been would be just the inflow volume, which I haven’t compiled yet. I suspect if we looked at it that way, this year would fare pretty well, but be nowhere near the phenomenal years of the mid-1980s, or even 1995 or 1997, all of which happened when the lake was nearly full—so there were huge releases in those years…
Which leads to the cloud in the silver lining—how much has this year helped in the overall big picture of water storage within the Colorado River system? The short answer is not much. A good way to measure this is the combined storage of Powell and Mead, which really work together as a single unit anyway. The combined storage capacity is roughly on the order of 50 MAF, about half in each reservoir. At their collective peak in 2018, the combined storage of the two reservoirs was about 23.2 MAF, or about 46.2% of total capacity. At this year’s peak, it’s up a bit, but not much—to 24.2 MAF, or 48.2% of capacity.
Why didn’t this year do more?
The long-term pattern of the two reservoirs since 1970 tells the story.
In the 1970s, the combined storage was slowly rising, from about 53% in 1970 to 95% by the end of the decade. In those years, the two lakes rose more or less simultaneously and consistently, a couple of down years offset by generally better than average years, and a couple of great ones, especially 1973 and 1979. In 1973, the collective storage rose 10%; in 1978-80, about 19%! At no time in that decade did it ever drop more than 3% in a single year. The pattern was heavy snowpack and minimal drought.
In the 1980s, the combined reservoirs were essentially full from 1980-87, continuing the precipitation pattern of the 1970s. But then it all changed. In just the years 1988-91, the reservoirs dropped nearly 25%. In 1989-90 alone, it dropped 13%. That kind of drop hadn’t happened before since Powell came online. And it showed how vulnerable the Colorado basin storage was to even a short but sharp drought. Those 4 years basically returned storage to 1971 levels.
The 1990s saw a steady recovery, until again the reservoirs were collectively close to full in 1998-99.
But the really big event was the drought of 2000-04. Combined lake volume was cut in half—from 94% in 1999 to just under 50% in 2004. Following the historically horrific year of 2002 alone, the reservoirs dropped 15%!
Since 2005, the combined storage has hovered at about 50%, never really recovering much. It has been a slow climb out, nudging up to 60% after a big 2011, but another short but sharp drought in 2012-13 erased those gains and more, ending up at about 45% in 2014. Since then, it climbed very slowly, barely touched 50% in 2017, otherwise, we’ve been sitting below the halfway mark. And unlike in earlier times, Mead is critically low. Until 2002, it always sat at close to 80% or better. Since then, a steady drop, now to less than 40%. You can’t really blame increased downstream (i.e., CA, NV, AZ) water use either, which has stayed consistently within the limits of the Law of the River in that time. There’s just not as much consistent upstream precipitation, especially snowpack.
So the story is that consistent rise and recovery takes years, and is a slow and steady climb, as in the 1970s or 1990s. But even a 2 to 4 year drought can quickly wipe out those gains or worse. So 2019, hopefully, is just the beginning of another slow climb after the setback of 2018…
. Slab City, the Venice of Americana in the Anza-Borrego desert? The quintessential autonom city state responsible for the conversions of RV’s to Houseboats.
We rename it Water World.
