JFRCalifornia
Keeper of San Juan Secrets
Well, the lake appears to finally have bottomed out on May 2 at 3599.26. That level is pretty much in line with what the USBR expected, but it sure took a long time to get there. May 2 is a very late date to bottom out. The lake usually hits bottom sometime in March or April, with the average being somewhere around April 1. Last year was April 10. When the lake keeps dropping into May, that’s usually not a good sign. Here are the years since 1990 where the lake hit bottom on or after May 1:
1990 – May 25 – 3648. Peaked at 3651 on June 19.
1991 – May 13 – 3627. Peaked at 3639 on June 30.
2000 – May 6 – 3676. Peaked at 3683 on July 2.
2002 – May 26 – 3644. Peaked a little over 3644 on May 31. Terrible year.
2003 – May 1 – 3605. Peaked at 3617 on June 23.
2013 – May 8 – 3596. Peaked at 3601 on June 18.
2015 – May 7 – 3590. Peaked at 3614 on July 14.
2018 – May 2 – 3609. Peaked at 3612 on June 10.
In terms of spring net volume increase in those years, here you go:
1990 – 0.30 MAF
1991 – 1.33 MAF
2000 – 1.14 MAF
2002 – 0.02 MAF
2003 – 1.17 MAF
2013 – 0.48 MAF
2015 – 2.37 MAF
2018 – 0.31 MAF
As a point of reference, in 2019 the lake added 4.95 MAF during the spring runoff.
Collectively, those 8 years are among the worst on record for net volume increase in the spring. Here’s where they rank all-time:
1990 – 53 (out of 58)
1991 – 40
2000 – 43
2002 – 55
2003 – 42
2013 – 50
2015 – 32
2018 – 52
In contrast, the net spring volume increase in 2019 ranked 6th all-time.
To be optimistic, we had a good snowpack up until March, and this may still pay dividends in the coming month as it really heats up. But I wouldn’t expect a miracle after the dry April, and if we’re lucky, we’ll see something like 2015, when the lake rose modestly thorough the spring into mid-July, adding about 24 feet, and a roughly average net volume increase. That year we started seeing the lake inflow hit 30,000 cfs on May 22, about 2 weeks after hitting bottom, ratcheting up to 50,000 cfs on June 6. It hit peak inflow rate on June 14 at a little over 53,000 cfs, before slowing down. That was a pretty average year.
On most of those other years, the peak inflow rate ranged from 23-33K cfs, with some outliers on either end. It was especially bad in 2002, with a max of 11K cfs, while it briefly flirted with 40-50K cfs in 2000 and 2003.
So let’s watch the inflow metrics over the next couple of weeks, and we’ll get a better sense of how this will likely play out into the summer.
1990 – May 25 – 3648. Peaked at 3651 on June 19.
1991 – May 13 – 3627. Peaked at 3639 on June 30.
2000 – May 6 – 3676. Peaked at 3683 on July 2.
2002 – May 26 – 3644. Peaked a little over 3644 on May 31. Terrible year.
2003 – May 1 – 3605. Peaked at 3617 on June 23.
2013 – May 8 – 3596. Peaked at 3601 on June 18.
2015 – May 7 – 3590. Peaked at 3614 on July 14.
2018 – May 2 – 3609. Peaked at 3612 on June 10.
In terms of spring net volume increase in those years, here you go:
1990 – 0.30 MAF
1991 – 1.33 MAF
2000 – 1.14 MAF
2002 – 0.02 MAF
2003 – 1.17 MAF
2013 – 0.48 MAF
2015 – 2.37 MAF
2018 – 0.31 MAF
As a point of reference, in 2019 the lake added 4.95 MAF during the spring runoff.
Collectively, those 8 years are among the worst on record for net volume increase in the spring. Here’s where they rank all-time:
1990 – 53 (out of 58)
1991 – 40
2000 – 43
2002 – 55
2003 – 42
2013 – 50
2015 – 32
2018 – 52
In contrast, the net spring volume increase in 2019 ranked 6th all-time.
To be optimistic, we had a good snowpack up until March, and this may still pay dividends in the coming month as it really heats up. But I wouldn’t expect a miracle after the dry April, and if we’re lucky, we’ll see something like 2015, when the lake rose modestly thorough the spring into mid-July, adding about 24 feet, and a roughly average net volume increase. That year we started seeing the lake inflow hit 30,000 cfs on May 22, about 2 weeks after hitting bottom, ratcheting up to 50,000 cfs on June 6. It hit peak inflow rate on June 14 at a little over 53,000 cfs, before slowing down. That was a pretty average year.
On most of those other years, the peak inflow rate ranged from 23-33K cfs, with some outliers on either end. It was especially bad in 2002, with a max of 11K cfs, while it briefly flirted with 40-50K cfs in 2000 and 2003.
So let’s watch the inflow metrics over the next couple of weeks, and we’ll get a better sense of how this will likely play out into the summer.
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