Brad Udall Profile picture
Oct 5, 2021 14 tweets 5 min read Read on X
/1 I spent the weekend looking at various locations on Lake Powell. A short thread follows on what I saw and my impressions. Lake Powell is the 2nd largest reservoir in the US. Since 2000 flows in #ColoradoRiver are down by 20%, half due to #climatechange.
/2 Here's a look at Powell contents since 2000. We're at 3545 (right axis) now, about 7 maf out of 25 maf possible. It is stunning how low the lake is.
/3 I visited Bullfrog Marina, the overlook that shows Hite Marina and the river now down cutting through 50-year-old lake sediments, the new Cataract Canyon takeout, Wahweap Marina, Glen Canyon Dam, and Antelope Point Marina.
/4 A year ago, Sept 2020, the lake was at ~3596 feet. Today it sits at ~3545, a drop of 50 vertical feet. It is now down 155 vertical feet from full at 3700. The lake was last at 3545 in March of 1969 when it was about 6 years old and still filling for the first time.
/5 At Bullfrog the main boat ramp had a dirt extension at the bottom to get to the water
/6 The ferry service from Bullfrog to Halls Crossing was closed because the ramp is not usable. If you look closely, you can see the carved out canyon at the bottom of the ramp. Like all of the ramps, it is a very long way from the top to the bottom.
/7 Here's the bottom of the ramp. The lake seems like a good half mile away.
/8 Looking back up the ramp. A walk to the top of the ramp might take you a good 10 minutes.
/9 Here's the Colorado River at the Hite overlook. You can see the old Hite boat ramp in the distance. This used to all be lake. Now the river is now down cutting through lake sediments in an incised channel.
/10 A view upriver from the overlook. The new Cataract Canyon takeout is visible.
/11 The Park Service has done a good job with a new temporary takeout for Cataract Canyon. Not too long ago, it was a challenge to take out here. River is just behind me.
/12 Old Floating Bathrooms at the take out seem very much out of place, but they work. Note the construction equipment on the right.
/13 Here's the end of the Hite boat ramp. It is a very long way to the river, several hundred yards. See #9 for another view of this ramp from afar.
/14 Here's the now closed main ramp at Wahweap.

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More from @bradudall

Oct 26, 2021
1. Previously I provided plots and threads of Lakes Mead and Powell contents separately. This short thread deals with the combined contents of both reservoirs and projections out to Aug 2023. The combined contents provides a complete view of the problem. #coriver #ClimateCrisis
2. This shows the combined contents back to 1935 when only Mead existed. In 1963 Lake Powell begins to fill. By 1983 the two are totally full -- even over full for a bit as Lake Powell had temp plywood boards installed to prevent downstream flooding.
3. By next year the combined contents will be below 30%, less than some years when only Mead existed before 1963. And the minimum probable projections put the contents around 20% (10 maf total) in 2023.
Read 10 tweets
Oct 22, 2021
1. Here are the 24 month Lake Powell projections to Aug 2023. Both last month (Sep) and this month (Oct) projections are shown for "minimum probable" and "most probable". #coriver #climatechange @R_EricKuhn @jfleck
2. The Min Probable projections for both Sep and Oct are well below safe minimum power elevation of 3525 for most of the projections and even below the top of the penstocks at 3490 for some time.
3. The Most Prob projections for Sep and Oct keep Powell in reduced releases to Lake Mead, 7.48 maf, thus ensuring Mead also drops.
Read 8 tweets
Oct 5, 2021
A 2nd thread on Lake Powell from this weekend. See earlier thread for Tweets 1-14.
/15 Here's the bottom of the Wahweap Stateline ramp, now closed.
/16 This is the recently opened Stateline replacement ramp. It opened just days ago.
Read 10 tweets
Jul 8, 2021
2. Reclamation’s ‘unregulated inflows’ into Lake Powell show that 2021 will be the 2nd worst year after only 2002 going back to 1964. 2021 will be the RED bar most likely. This is a really grim year for runoff.
3. 2021 Inflow will be only ~3 maf, compared to the 1981-2010 average of 10.3 maf or the 2000-2021 average of 8.3 maf (20% less than 1981-2010 average).
(maf = million acrefeet)
4. Considering that Powell will release / evap ~ 8.5 maf, the lake will lose ~ 5 maf this year or ~55 feet of elevation.
Read 19 tweets

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