“Climatic water deficit” is the culprit in Aspen forests dying in the southwestern US


From The Week (Ryan Cooper):

A team of scientists, led by Dr. William Anderegg of Princeton, have been working on the aspen question, and their results were published today in Nature Geoscience. The answer is something called “xylem cavitation.” And unless we do something big about climate change soon, it will kill most of the aspens in the Southwest.

Here’s what that means. Trees transport water through their xylem tissue (one example of which is regular old wood), basically composed of millions of tiny tubes, or “conduits.” Xylem doesn’t work like a mechanical pump — instead, water flows up the tree trunk through capillary action. That flow is maintained through evaporation at the leaf surface, removing water at the top so more can replace it, and supplied by the roots drawing water from the soil.

In hot, dry conditions, like the early 2000s drought, water evaporates more quickly from the leaf surface — and there is less water in the soil to maintain supply. Anderegg and his team quantified both of these with a factor they called “climatic water deficit.” When the deficit is high, the water pressure inside the xylem decreases due to tension between the top and bottom of the tree.

If the pressure gets low enough, gas bubbles will spontaneously form in the water column — which is called cavitation. A bubble instantly blocks that particular xylem conduit and prevents the water from flowing. Block enough conduits, and the tree desiccates and dies.

It’s “like a tree heart attack,” says Anderegg. He and his team constructed a model of this cavitation mechanism, calculated a threshold at which aspens should die, and compared it with historical data on the early 2000s drought. They found pretty clear agreement, explaining about 75 percent of the tree mortality during that time (a good result, given how complex forests are).

2015 Colorado legislation: SB15-064 (Application Of State Water Law To Federal Agencies) dead #coleg

Photo via Bob Berwyn
Photo via Bob Berwyn

From The Colorado Statesman (Marianne Woodland):

SB 64 sailed through the Senate Agriculture, Natural Resources and Energy Committee on an 8-1 vote. That included a “yes” vote from Sen. Kerry Donovan, D-Vail, whose district includes the Eagle County ski areas, as well as Crested Butte and Aspen. Sen. Mary Hodge, D-Brighton, also voted in favor of SB 64.

On the Senate floor, the bill picked up four more votes from Democrats, and passed on a 24-11 vote.

But instead of going to the House Ag Committee, where the previous versions had passed easily the last two years, SB 64 was assigned to the State, Veterans and Military Affairs Committee. And true to its reputation as the “kill” committee, the bill died on a 5-6 party-line vote. One of those “no” votes came from Rep. Mike Foote, D-Denver, who voted in favor of the 2014 version.

Sonnenberg was furious. He told The Colorado Statesman last week that it was just politics. “I don’t get it,” he said. “It’s politics at its worst, when we don’t defend Colorado water rights owners.”

This week, House Speaker Dickey Lee Hullinghorst, D-Boulder, defended her decision to send SB 64 to the State Affairs committee, and why she made that decision on a bill she’s supported for the past two years.

Hullinghorst said Tuesday she sent the bill to State Affairs because she wanted to see the issue addressed more broadly, and that she believed State Affairs was the appropriate committee. She said she changed her mind on the bill because of a legal opinion from Legislative Legal Services, although Legal Services issued the same opinion for the 2013 and 2014 bills.

“I believe that issue has been well-vetted, and we’ve had lots of good talk about it. But as a matter of fact, we have memos from Legal Services that tell us on two specific constitutional issues, that this bill is unconstitutional,” Hullinghorst said this week.

The first issue, according to the Legal Services memo, is that the federal government has preemption powers in this area. Preemption means that when a federal and state law conflict, the state law is considered invalid.

Second, the memo said the bill is considered special legislation since it is done for one specific agency. Hullinghorst said that bothered her more than the preemption issue. “I used my prerogative, I changed my mind.”

More 2015 Colorado legislation coverage here.

Snowpack news: The Upper #ColoradoRiver Basin (in Colorado) has started melting out

@USGS: Streamflow of 2014 — water year summary

More USGS coverage here.

Colorado’s snow is dust-free for the first time in a decade — the High Country News

Click on a thumbnail graphic to view a gallery of snowpack data from the Natural Resources Conservation Service.

From the High Country News (Krista Langlois):

This year, however, there appears to be a break in the cycle: Though a few storms have swept east from the plateau, they either haven’t had enough oomph to carry dust to the mountains, or they’re coming from places like eastern Utah where the dust was tamped down by late-winter snowfall. For the first time in a decade, March snowpack across Colorado is virtually dust free. Great news, right?

Not really, says Chris Landry, executive director of the Center for Snow and Avalanche Studies in Silverton, Colorado. Rather than cause for celebration, current dust- and snowpack conditions are about as close to worst-case scenario as you can get. For one thing, above-average temperatures statewide mean that in each of the 11 locations Landry sampled last week, the snow itself was “much warmer than usual. In some places,” he adds, “it was as warm as you can get and still be snow — warmed up all the way to zero degrees Celsius.”

Once snow hits that threshold, Landry says, it’s very unlikely to cool down again — meaning that even if skiers are lucky enough to get a few spring dumps, snowmelt in many places has passed a point of no return. Already, some stream gauges are showing runoff well above annual norms for this time of year.

Secondly, there’s just not much snow to begin with. In most Colorado watersheds, snowfall was subpar, and a long, dry, warm spell that lasted through February caused some slopes to become nearly bare — creating even more variation than usual between sunny, south-facing slopes and cool, shady ones. When Landry tramps around visiting data sites, he’s used to seeing a difference between conditions on the ground and the computer-generated SNOTEL maps, because SNOTEL sample sites tend to be flat and shady. This year, however, Landry worries the variations are higher than usual — so even maps showing snowpack at 67 percent of normal may be overstating what’s really out there. Less snow ultimately means faster rates of melting, and faster melting now means less water in streams and rivers this summer.

The last criteria for Landry’s “worst-case scenario” is a dry spring — which is exactly what we’ve had so far. Just as there have been few storms here in the mountains, there haven’t been many over the Colorado Plateau either, and that means conditions there are getting drier and dustier — primed for a big April dust storm. April is typically the biggest month of the year for dust events, and May isn’t far behind. So just because there’s virtually no dust out there right now doesn’t mean it’s not coming: “The Colorado Plateau is drying out,” Landry says, “And that almost ensures that if and when a major weather system moves through, dust will be available. We’ve had single dust events that in and of themselves would be more than adequate to really alter snowmelt.”

“Everybody is hoping for no dust,” he adds. “And that would be considered a good thing. But it’s also true that we’re a long way from being even reasonably hopeful that will be the case.”

From TheDenverChannel.com (Matt Makens):

The fire danger has increased this March. This is due to an unusually warm pattern with little moisture for most of Colorado.

The first week of March started with snow/rain and cool temperatures but the following three weeks were very warm and very dry.

The monthly average temperature was 4 to 8 degrees warmer than average for the state. Temperatures were near their averages for only a few days. Denver ends March more than 4-degrees warmer than its average…

This follows a dry start to the year. For three months in a row, temperatures remained warmer than average. This year, the only area of the state to have above average precipitation is a region of the Front Range along I-25 from Denver to New Mexico.

This dry and warm start to the year has raised concerns of the fire danger for the coming months.

Meteorologist Tim Matthewson of the Bureau of Land Management tells 7NEWS that the next 30 to 60 days will be critical for the fire season. To continue with below average precipitation could mean a bad fire season. He added, this is reminiscent of 2012, although not quite there yet.

“First and foremost, Western water is about politics, not policy” — Dan Beard #ColoradoRiver


From KUER (Judy Fahys):

The West used to solve its water troubles with dams. But now Dan Beard. a man who used to lead the nation’s dam-building agency, wants to shutter it.

Beard once oversaw the U.S. Bureau of Reclamation’s vast water network in the West, and he helped Congress decide on one billion dollars worth of finishing touches for the Central Utah Project.

But Beard says the water landscape has changed.

“In the middle of a drought, with climate change here and going to impact the horizon,” he says, “water is a much more active and high-priority issue.”

In his new book, Deadbeat Dams, Beard argues that the “Bureau of Wreck” – or W-R-E-C-K , as environmentalists used to call it – is a bureaucratic waste. He also advises tearing down the Glen Canyon Dam to make the Colorado River more efficient.

Beard says the water bureaucracy resists change.

“There are several things you’ve got to keep in mind when you talk about Western water,” he says. “First and foremost, Western water is about politics, not policy. The second thing is logic and common sense rarely play a role in resolving water problems.”

He calls conservation, smarter water pricing and innovation crucial to finding solutions.

More Colorado River Basin coverage here.

Southern Delivery System: The Pueblo County commissioners take first step to evaluate Colorado Springs’ 1041 permit compliance

Fountain Creek Watershed
Fountain Creek Watershed

From The Pueblo Chieftain (Jeff Tucker):

The Pueblo Board of County Commissioners got a first look at a resolution that will allow the board to retain legal counsel along with engineering consultants and other staff to evaluate whether Colorado Springs’ lack of any consistent stormwater funding is a deal-breaker for the Southern Delivery System.

The board took no official action on the measure, instead instructing attorneys Gary Raso and Ray Petros to fine-tune the resolution before it comes back for a vote.

The crux of the issue is the failure of a ballot measure in Colorado Springs in November that would have created a dedicated funding source for stormwater improvements in Colorado Springs that could mitigate the impact of runoff into the Fountain Creek.

The work that would be cleared by the resolution will allow staff to examine what’s been done so far and what still needs to be done for Colorado Springs to comply with the stormwater requirement in the SDS 1041 permit.

“We need to develop a factual basis for any action we take,” said Raso. “It would be the first time that Pueblo County would have an independently established set of facts about the stormwater flowing through the Fountain Creek.”

Petros told commissioners Monday that Colorado Springs has provided staff a summary of its stormwater expenditures.

Colorado Springs has indicated that it has budgeted $17 million this year for more improvements, but Petros said there’s yet to be any indication what those improvements are or if they’re among the 239 projects worth more than $534 million identified in 2013.

Commissioner Sal Pace said he wants a clear picture on what projects Colorado Springs has planned that directly mitigate impacts on the Fountain Creek and which ones are aimed at fixing the challenge of runoff from the various burn scars in the area.

It’s possible that building flood control projects for the burn scar will have an impact on the flooding in Fountain Creek. But Commission Chairwoman Liane “Buffie” McFadyen wondered whether the impacts of the Waldo Canyon Fire are accounted for under the current agreements over the SDS, since those were signed before the first spark of the catastrophic fire ever landed.

McFadyen also worried that the work set forth in the resolution may be at odds with the needs of the county’s own constituents in Pueblo West. The metro district ties into SDS.

“I don’t want to see Pueblo West used in a way that could be interpreted as gamesmanship in all of this,” she said.

Commissioner Terry Hart noted that the $50 million being paid to the Fountain Creek Watershed Flood Control and Greenway District likely won’t be enough to pay for the mitigation projects in Pueblo County and asked Petros and Raso to include a specific date in the resolution as to when the information will be ready.

Petros suggested the end of June, to give the newly elected mayor and City Council time to get sworn in after April 7 elections and for next month’s lawsuit over compensation by Colorado Springs to Walker Ranches to run its course.

However, Hart said he’d like to see it sooner.

“I didn’t create this problem,” he said. “What created this problem was the failure of the question in November.”

More stormwater coverage here.

What severe drought in the #ColoradoRiver Basin looks like — The Washington Post

Colorado River Basin including out of basin demands -- Graphic/USBR
Colorado River Basin including out of basin demands — Graphic/USBR

Click here to read the article from The Washington Post (Nick Kirkpatrick) and to check out the photo gallery from Lake Powell. Here’s an excerpt:

Lake Powell, one of the nation’s largest reservoirs, is now below 45 percent of its capacity.

Straddling the border between Utah and Arizona, the man-made reservoir is part of the Colorado Water Basin that supplies water to 40 million people…

For more than 14 years, the basin and the Western states have been plagued by drought. Almost every year, all of the water from the Colorado River is pumped out before emptying into the the Gulf of California.

“Many climate scientists think the Southwest is again due for a megadrought,” Jonathan Waterman wrote in National Geographic. “The Bureau of Reclamation’s analysis of over a hundred climate projections suggests the Colorado River Basin will be much drier by the end of this century than it was in the past one, with the median projection showing 45 percent less runoff into the river.”

More Colorado River Basin coverage here.