From Aspen Journalism (Brent Gardner-Smith):
Tell experienced river runners that 2 million acre-feet of water — as much water as in 20 Ruedi Reservoirs — is going to be released from reservoirs and sent down the Green, Gunnison and San Juan rivers to boost falling water levels in Lake Powell, and they will likely have some good questions.
Will peak spring releases from Flaming Gorge Reservoir down the Green River turn Hell’s Half Mile in the Gates of Lodore into a raging maelstrom?
Will early-spring and late-summer releases out of Navajo Reservoir on the upper San Juan River make it easier to float over the growing sandbars in the river below Grand Gulch?
Will releases from Blue Mesa Reservoir run down the Gunnison River and into the Colorado River and make it likelier that flows past Skull Rapid in Westwater will stay longer in the “terrible teens,” or at flows over 13,000 cubic feet per second?
For now, there are no definitive answers to such questions, but one federal official suggests boaters may hardly notice the release of water from the three reservoirs.
An agreement was approved last week in Las Vegas by the Upper Colorado River Commission that sets up a process for Colorado, Utah, Wyoming and New Mexico, and the federal Bureau of Reclamation, to develop a plan to release about two million acre-feet of water from the three reservoirs, but it is, at this point, only an agreement to make a “drought operations” plan, when necessary.
“The agreement, importantly, doesn’t itself include a plan. Rather, it sets forth a process for establishing a plan based on modeling projections of Powell elevations,” Amy Haas, the director of the UCRC said during a presentation here last week at a meeting of the Colorado River Water Users Association.
Still, boaters want to know, where might the water come from under such a plan. When it will come? And will it make a difference on the river?
The answer to the last question, at least, is something akin to “no, not really.”
“I really don’t think it is going to be noticeable, because we see quite a bit of fluctuation in the upper basin in all of these systems, when we have abundance and when we have drought, and this fits within those bands,” said Brent Rhees, the regional director in the upper Colorado River basin for the Bureau of Reclamation, which operates Flaming Gorge, Blue Mesa and Navajo reservoirs, as well as Lake Powell.
It also says water will be released from all three reservoirs, though not necessarily at the same time, and an effort will also be made to balance hydropower needs.
The agreement gives regional water managers “sufficient flexibility to begin, end or adjust operations as needed based on actual hydrologic conditions” and retains Reclamation’s current authority to release water as it sees fit, within existing approvals, if there is an “imminent need to protect the target elevation at Lake Powell.”
(Also, please see related agreements on demand management storage in Lake Powell, a “companion agreement” to an a drought contingency plan agreement in the lower basin, and Exhibit 1 to that agreement).
Flaming Gorge, Navajo and Blue Mesa reservoirs were built, in large part, to serve as backup buckets to Lake Powell, but they have yet to be called upon for such duty.
Of the three reservoirs, Flaming Gorge is the largest, with a capacity to hold 3.8 million acre-feet of water behind its dam, which is in Utah near the Wyoming border.
Navajo Reservoir, which is in northern New Mexico, on the San Juan River, holds 1.7 million acre-feet.
And Blue Mesa Reservoir, one of three dams on the Gunnison River that make up what’s called the Aspinall Unit, holds 940,800 acre-feet.
Of course, before water can be released from reservoirs, they must have water in them — and that’s no longer a given.
Today, according to the Bureau of Reclamation, Blue Mesa is only 30 percent full, holding 248,220 acre-feet of water; Navajo is 52 percent full, holding 883,737 acre-feet; and Flaming Gorge is 88 percent full, holding 3.3 million acre-feet. (Please see “teacup” graphic, with current reservoir levels).
The water to be released, if needed, from the three reservoirs is meant to help maintain a target elevation for the surface of Lake Powell — as measured at the upstream face of Glen Canyon Dam — of 3,525 feet above sea level.
Today, Lake Powell is at 3,584 feet, or 59 feet above the target elevation. A year ago, the lake was at 3,623 feet, or 39 feet higher than it is today. (Lake Powell is 42 percent full, holding about 10.4 million acre-feet of water.)
So, if very dry conditions persist in the upper basin and the reservoir level keeps falling more than 30 feet a year, it’s possible that the critical elevation of 3,525 could be reached within two dry years.
The most recent 24-month forecast — issued by the Bureau of Reclamation on Wednesday — “projects Lake Powell elevation will end water year 2019 (at the end of September) near 3,571.23 feet with approximately 9.21 million acre-feet in storage,” or at 38 percent of capacity.
That means by October, Lake Powell is already projected to be 13 feet lower than it is today and only 46 feet above the target elevation of 3,525 feet.
Nothing physically occurs at Glen Canyon Dam at 3,525 feet, but it’s seen by regional water managers as an alarm bell on the way to the reservoir falling to 3,490 feet, or minimum power pool, which is when water can no longer be sent down intake tubes to the turbines in the dam.
At elevations below 3,490, when the reservoir is heading toward “dead pool,” it becomes ever harder to release water downstream through the dam’s outlets, which could mean the upper-basin states would fail to meet their collective obligation to send enough water to the lower-basin states (California, Arizona and Nevada) under the 1922 Colorado River Compact.
Although violating the compact was once seen as a far-off, distant possibility, it’s not seen that way anymore.
“In water year 2018, unregulated inflow volume to Lake Powell was 4.6 million acre-feet (43 percent of average), the third-driest year on record above 2002 and 1977,” says the Bureau of Reclamation’s latest forecast, issued Wednesday.
It also says that inflows into Lake Powell have been above average in only four of the past 19 years.
“The latest hydrology is sobering,” Bureau of Reclamation Commissioner Brenda Burman said last week during remarks at the water conference. “It is time for us to pay attention. We are quickly running out of time.”
Editor’s note: Aspen Journalism covers water and rivers with The Aspen Times. The Times published this story on Monday, Dec. 17, 2018.