@USBR: The next Aspinall Unit operations meeting is Thursday #ColoradoRiver #COriver

Aspinall Unit dams
Aspinall Unit dams

From email from Reclamation (Eric Knight):

The next Aspinall Operations meeting will be held this Thursday, August 18th at the Elk Creek Visitor Center at Blue Mesa Reservoir. Start time is 1 PM.

#La Niña: The latest ENSO diagnostic discussion is hot off the presses from the Climate Prediction Center

Forecasts of sea surface temperature (SST) anomalies for the Niño 3.4 region (5°N-5°S, 120°W- 170°W). Figure updated 18 July 2016.
Forecasts of sea surface temperature (SST) anomalies for the Niño 3.4 region (5°N-5°S, 120°W- 170°W). Figure updated 18 July 2016.

Click here to read the current discussion. Here’s an excerpt:

ENSO Alert System Status: La Niña Watch

Synopsis: La Niña is slightly favored to develop during August – October 2016, with about a 55-60% chance of La Niña during the fall and winter 2016-17.

ENSO-neutral conditions were observed during the past month, featuring slightly below average sea surface temperatures (SSTs) close to the equator across the eastern tropical Pacific Ocean. While the weekly Niño-1+2 and Niño-4 regions were near average, the Niño-3 and Niño-3.4 indices were slightly below average (approaching -0.5oC) during July. Although below-average subsurface temperatures continued, they weakened during the past month but remained near the surface in parts of the central and eastern equatorial Pacific. Atmospheric anomalies over the tropical Pacific Ocean also indicated ENSO-neutral conditions. Both the traditional Southern Oscillation index and the equatorial Southern Oscillation index were near average during July, while the upper and lower-level winds also were near average across most of the tropical Pacific. Convection was suppressed over portions of the western and central tropical Pacific and enhanced over part of Indonesia. Overall, the combined ocean and atmosphere system is reflective of ENSO-neutral.

Many models favor La Niña (3-month average Niño-3.4 index less than or equal to -0.5°C) by the beginning of the Northern Hemisphere fall, continuing into winter. Statistical models predict a slightly later onset time (i.e., mid- to late fall) than dynamical models, and also predict a slightly weaker event. The forecaster consensus favors La Niña onset during the August-October season, and predicts a weak event (Niño-3.4 index between -0.5°C and -1.0°C) if La Niña forms. Overall, La Niña is slightly favored to develop during August – October 2016, with about a 55-60% chance of La Niña during the fall and winter 2016-17 (click CPC/IRI consensus forecast for the chance of each outcome for each 3-month period).

#ColoradoRiver: #Drought like 2000-2006 would empty Lake Powell — Aspen Daily News #COriver

Lake Powell via Aspen Journalism
Lake Powell via Aspen Journalism

From The Aspen Daily News (Brent Gardner-Smith, Aspen Journalism:

From his office along the Colorado River in Glenwood Springs, Eric Kuhn can see the bottom of Lake Powell.

Kuhn, the general manager of the Colorado River District, has been working for months on a study asking if future droughts will drop water levels in Lake Powell so low that Glen Canyon Dam won’t be able to produce hydropower or release enough water to meet downstream demands.

“If we were to have another 2000-2006 drought, with where our starting conditions are today, we would basically empty Lake Powell,” Kuhn told the board of directors of the river district last month in an update on the study. “Now, we’re not going to do that. No one will allow Lake Powell to become empty.”

But today, Lake Powell is already half-full after one of the driest 15-year periods on record in the upper basin.

And Kuhn said no one wants to see a “compact call” triggered because Colorado, Wyoming, and Utah fail to deliver enough water through the Glen Canyon Dam to California and Arizona.

Such a call could prevent those who own post-1922 water rights from diverting water from the river. And that includes most of the transmountain diversions in Colorado.

“As long as you keep water in Powell above minimum power [pool], you’ll never have a compact problem,” Kuhn told the board.

So the $52,000 risk study Kuhn is working on with Hydros Consulting of Boulder is looking at how much water the upper basin states may have to send to keep Lake Powell above two key elevations.

The first important elevation is 3,525 feet, which triggers an operational guideline for how the reservoir is managed. The second is 3,490 feet, which is the “minimum power pool” below which hydropower cannot be produced at Glen Canyon Dam.

Failure to meet the operational guideline could require, ironically, that the upper basin states release even more water, depending on the level of Lake Mead, thus dropping the water level in Powell even faster toward minimum power pool.

And failure to stay above minimum power pool could prevent the eight turbines inside Glen Canyon Dam from producing about $120 million worth of electricity a year.

Buyers of that electricity include the cities of Aspen, Glenwood Springs, Delta, Gunnison, and Colorado Springs and utilities including Holy Cross Electric Association and Public Service Co. of Colorado.

Once minimum power pool is reached, it may also be difficult to physically move enough water through the dam’s infrastructure to meet the terms of the Colorado Compact.

On Saturday, Aug. 13, the surface of Lake Powell was at 3,617 feet and was 52 percent full.

The reservoir can hold 26,215,000 acre-feet of water at full elevation of 3,700 feet, according to the Bureau of Reclamation.

Although the past three years have yielded average precipitation in Colorado, the period from 2000 to 2015 brought the lowest flows over any 16-year period since Glen Canyon Dam was completed in 1963, according to Reclamation.

The current operational guidelines provide that the upper basin now needs to release 8.23 million acre-feet (maf) of water a year to the lower basin, which Kuhn said has made significant progress on reducing its water usage and has set ambitious goals to use even less.

But Kuhn, and many other regional water managers, still want to know what will happen if drought returns while Lake Powell is half-full, as it is today.

What the study shows

The first phase of the study is now about three-quarters complete, Kuhn told the Colorado River District board in July.

The study’s methodology assumes only modest future water-supply development and then applies data from three different droughts in the last 25 years: the drought of 1988 to 1993, the drought of 2000 to 2006, and the drought of 2013 to 2014.

Kuhn said the model is showing, even with little new growth, that the upper basin can expect shortages ranging from 300,000 to 500,000 acre-feet in a relatively moderate drought.

In a severe drought Kuhn said the shortages could range from 500,000 to 1 million acre-feet, and in a drastic drought, some years could bring shortages of 1 million to 1.5 million acre-feet.

“This is what I call the ‘sticker shock,’” Kuhn said of those figures. “Basically, what we’re saying is if we were to have, under today’s conditions, one of these three droughts, we would go below our target of 3,525 feet.”

Another potential conclusion from the risk study is that any new transmountain diversion would only make it more likely that Powell would go below target levels.

“What we’re suggesting is that a new transmountain diversion could still divert, but only if there’s enough water in Lake Powell,” Kuhn told the board.

Kuhn put it another way during a presentation to the Gunnison River basin roundtable on Aug. 1.

“It is going to be a very high burden to show that a new transmountain diversion won’t impact system usages,” he said.

In fact, Kuhn said the model is showing that there has only been one year since 2000 that a new transmountain diversion wouldn’t have had a negative impact.

“So are you going to build a multibillion dollar project that is going to operate once in 20 years?” Kuhn said in Gunnison. “I don’t think so.”

That’s if the operator of such a system agrees not to divert in years that would hurt levels in Lake Powell, which is not a legal obligation under Colorado water law.

If there was no agreement to limit diversions, Kuhn said a new transmountain diversion that lowers levels in Lake Powell would mean that other water users in Colorado would have to cut back on their water use, and do so more frequently, perhaps as much as half of the years in the study’s 25-year forecast period.

“That’s a fairly important message,” Kuhn told the River District board.

And, he said, that’s without the increasing heat of climate change factored in.

“I haven’t shown the climate change hydrology because it just scares everybody,” Kuhn said. “This is the recent hydrology.”

Several options

Kuhn says water users in the upper basin have three main levers they can pull to keep Powell operational.

One is to continue cloud seeding 
efforts, which are underway but only marginally helpful.

A second is to release water from three big upstream reservoirs: Flaming Gorge Reservoir on the Green River, Navajo Reservoir on the San Juan River, and Blue Mesa Reservoir on the Gunnison River.

Those reservoirs “have the same purpose as Powell, which is to allow the upper basin to manage for the upper basin’s obligations,” Kuhn said.

Those three reservoirs can together release about 2 maf if needed, but they would be hard pressed to do that several years in a row, Kuhn said.

A third lever is to pay ranchers and farmers to fallow fields and leave the water in the river to run downstream to Lake Powell, often called “water banking” or “demand management.”

Demand management means using less water, or curtailing the amount of water put to a consumptive use.

In a severe multi-year drought, the system will need the releases from the three big reservoirs above Lake Powell and a lot of demand management, Kuhn said.

So what’s the tolerance for the risk that water levels will drop far enough in Powell to make significant levels of “demand management” necessary?

Kuhn said if we assumed a severe drought comes only twice in a 50-year period, we might just say, “we can live with it.”

And if drastic droughts occur three or four times in a 50-year period, Kuhn said, “we can probably, with the tools that we have and can reasonably implement, be able to address” the challenge.

But if there is a severe drought like 2000 to 2006, he said, “it will take the system beyond what we can do and then you’re going to have some big problems. That’s the message that the study suggests. The other message is, future demand matters.”

Editor’s note: Aspen Journalism and the Aspen Daily News are collaborating on coverage of rivers and water. More at http://www.aspenjournalism.

Why your water bill is going up

Mile High Water Talk

New rate structure still rewards conservation while helping us upgrade our system in a fluctuating climate.

By Travis Thompson

We’re getting a lot of questions about our new rate structure.

No surprise there. With multiple tiers of pricing, indoor and outdoor usage totals, and higher fixed charges to meet infrastructure demands and the extreme weather fluctuations of climate change, water rates are complex and often confounding.

Denver Water crews proactively install or replace an average of 60,000 feet of pipe throughout our service area per year. About $11 million will go to main replacement and main improvement in 2016 and $130 million will be invested in main replacements over the next 10 years. Denver Water crews proactively install or replace an average of 60,000 feet of pipe throughout our service area per year. About $11 million will go to main replacement and main improvement in 2016 and $130 million will be invested in main replacements over the next 10 years.

But of all the questions, one stands above all the others.

Is my bill going up?

That’s a straightforward question, and the simple answer is yes.

Not necessarily everyone’s bill, and not by the same amounts…

View original post 1,431 more words

South Denver Metro Shares Lessons on Path to Sustainable Water Future

Your Water Colorado Blog

By Eric Hecox

This month the South Metro Water Supply Authority, with our technical consultants CH2M, released a comprehensive assessment of the South Denver Metro region’s water future.

The study shows we have come a long way from the days of front-page headlines decrying the region as “running dry.” We can now say with confidence that we are on the path to a secure water future. We know where we’re going, and we know how to get there.

The results are summarized in recent newspaper articles (“The Future Looks Bright for Local Water Sources”) and on our website. In short, we have accomplished three major goals:

  • We have made significant progress in transitioning to a renewable water supply that will continue to become more balanced over time. By 2065, renewable water sources will account for 85 percent of our water supply, up significantly from just 12 years ago.
  • We…

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Warm Nights Tip the Scales as Summer Grinds On — WunderBlog

From WunderBlog (Bob Henson):

Data for July 2016 make it clear that this summer is worming its way into the nation’s warmest batch on record, thanks in large part to consistently sultry nights in many areas. Meteorological summer so far–June plus July–has been the fifth warmest for the contiguous U.S. in 122 years of recordkeeping, according to the July climate report released on Thursday by NOAA’s National Centers for Environmental Information (NCEI). Ahead of 2016 at this point are the scorching Dust Bowl summers of 1934 (#4) and 1936 (#1) along with the recent 2006 (#3) and 2012 (#2). The toasty summer so far is the result of the nation’s warmest June on record followed by its 14th warmest July. Last month’s warmth was focused across the nation’s southern and eastern halves (see Figure 1), with New Mexico and Florida each recording their hottest July on record. Fourteen other states made it into their top ten warmest for July.

Statewide rankings for average temperature during July 2016, as compared to each July since 1895. Darker shades of orange indicate higher rankings for warmth, with 1 denoting the coldest month on record and 122 the warmest. Image credit: NOAA/NCEI.
Statewide rankings for average temperature during July 2016, as compared to each July since 1895. Darker shades of orange indicate higher rankings for warmth, with 1 denoting the coldest month on record and 122 the warmest. Image credit: NOAA/NCEI.

Warmest nights on record for June-July
It’s the muggy nights that are imprinting themselves on the psyche of millions of Americans this summer. The average daily minimum for the contiguous U.S. was the warmest on record for June and July combined: 60.57°F, beating out 2015, 2010, 2002, and 2006. (See Figure 2.) Warmer nights are a hallmark of a climate being heated by added greenhouse gases, and it’s long been recognized that nights should generally warm more than days, and winters more than summers, as climate change proceeds. Of the eight June-July periods with the warmest average daily temperatures (including both highs and lows), four are from Dust Bowl years. However, the eight years with the warmest average daily minimum temperatures are all from the 21st century. Urban heat islands are no doubt helping to increase overnight lows in large metropolitan areas; however, the nationwide extent of the trend toward warm nights goes well beyond this effect.

For the year to date through July, the U.S. has seen 15,061 daily record highs and just 2709 record daily lows, according to data compiled by meteorologist Guy Walton. In an email, Walton told me that “2016 is in a race with 2012 for that dubious distinction of having the highest ratio of record daily highs to record daily lows since 1920.”

[…]

Wet to the north, dry to the south
After an unusually dry June across the contiguous U.S., July produced generous rains across much of the nation’s northern tier, while leaving most of the Northeast and the nation’s southern half on the dry side. It was the second-driest July on record for Georgia and the third-driest for Florida, with Wyoming and New Mexico also coming in among their top-ten driest. July was among the ten wettest on record in five states: Illinois, Kentucky, Minnesota, Missouri, and North Dakota. The weekly U.S. Drought Monitor issued on Thursday morning shows that more than 40% of California remains in extreme or exceptional drought, a situation that is unlikely to change before the 2016-17 wet season arrives (if then). Much of the state remains extremely vulnerable to fast-growing wildfire, especially over the next several months. Wildland fire potential is also expected to increase across the South this autumn, according to the latest outlooks from the National Interagency Coordination Center. (Torrential rains scattered over parts of the upper Gulf Coast this week will help tamp down the immediate drought and fire risk in those areas.)

The wet-north/dry-south tendency evident in July may be a foreshadowing of La Niña influence to come (see Figure 4 below). The strong El Niño of 2015-16 is giving way to borderline La Niña conditions, with the weekly index of sea-surface temperatures in the Niño3.4 region hanging near the -0.5°C threshold of La Niña over the past month. NOAA maintained a La Niña Watch in its monthly ENSO discussion issued Thursday, although the event is projected to be relatively weak if it does take shape. NOAA is giving a 55-60% chance of La Niña being present this fall and winter and a negligible chance of El Niño (below 10%). Because La Niña typically leads to a more consolidated jet stream, it often leaves southern parts of the 48 states on the dry side of upper-level flow as storm systems whip across the nation’s heartland, keeping northern areas more moist.