Posts Tagged ‘Snowpack’

Early season turnaround bodes well for water supply

Despite a parched start to winter, snowpack levels are on track thanks to a snowy December and early 2017 storms.

Denver Water's Winter Park crew works around the clock to ensure facilities are accessible during snowstorms.

Denver Water’s Winter Park crew works around the clock to ensure facilities are accessible during snowstorms.

By Travis Thompson

Like carpenters, water supply managers use an assortment of tools to get the job done. But instead of tape measures and hammers, their tool boxes are filled with charts and graphs, computer models and good old-fashioned experience.

With 80 percent of Denver’s water supply coming from snowmelt, no tool is used more during the winter months than the charts showing snowpack levels in the mountains above Denver Water’s facilities.

And this year is proving to be one of the more interesting in recent memory.

With more than half of the snow season still ahead, water managers have already seen near historic lows and highs to kick off the winter.

“Our team was starting to sweat a little bit this fall — literally and figuratively — with the unseasonably warm and dry weather,” said Dave Bennett, water supply manager for Denver Water.

In late November, snowpack levels in areas feeding the streams and rivers that flow into Denver’s mountain reservoirs were only 10 percent to 20 percent of normal.

Denver Water’s reservoirs were still above average because of the good water years carried over from 2014 and 2015, as well as efficient water use in the Denver metro area.

But the dry start to winter had Denver Water planners on edge.

“I knew that a couple of good storms would have us back to normal,” said Bennett. “It was too early to panic — well, that’s what I kept telling myself at least.”

Thankfully, he was right.

On Jan. 5, water supply manager Dave Bennett talked to 9News reporter Colleen Ferreira about the improved snowpack levels in Denver Water's collection area.

On Jan. 5, water supply manager Dave Bennett talked to 9News reporter Colleen Ferreira about the improved snowpack levels in Denver Water’s collection area.

In December, Denver Water’s Colorado River basin collection area received almost double the amount of accumulation than normal, with approximately 60 inches, making it the sixth snowiest December for this area over the past four decades.

Similarly, the South Platte River basin collection area that feeds Denver’s reservoirs received approximately 40 inches of snow compared to the normal 20 inches, making it the fifth snowiest December in this location over the same 40-year time period.

Couple that with the early 2017 snowstorms, and snowpack levels are now 137 percent and 128 percent of normal in the Colorado River and South Platte River watersheds — and, it’s still snowing!

It was such a significant turn of events that Bennett was featured on 9News, talking about the importance of the recent snow, not only for water supply but also for Colorado’s greatest asset: outdoor recreation.

“I’ve never seen an early season turnaround like it,” said Bennett. “But we still have a long way to go. A lot can happen between now and spring — the months we rely on the most for snowpack are still ahead of us.”

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Warm weather, wildfires and watersheds

How reducing the risk of catastrophic wildfires improves the quality of water flowing into our reservoirs.

By Steve Snyder

Not cool, bro.

Land near Cheesman Reservoir was severely damaged after the 2002 Hayman Fire.

Watershed lands near Denver Water’s Cheesman Reservoir were severely damaged after the 2002 Hayman Fire.

That’s one way to describe the warm, dry fall we experienced in Colorado this year, not only from a temperature standpoint, but from a broader view of what these conditions mean to our water supply.

Denver Water gets almost all of its supply from mountain snowmelt, so the lack of snow so far is a bit concerning. But weather like this also has a big impact on another part of our system — our watersheds. As melting snow travels downhill, it may pass through forests, farmland and even commercial, industrial and urban areas. This land is called a watershed, and it directly impacts the quality of water that eventually gathers in Denver Water’s reservoirs.

And warm fall weather only increases the risk of wildfires in our watersheds. In fact, a recent paper in Proceedings of the National Academy of Sciences suggests the effects of climate change are making forests in the Western United States drier and easier to burn, thus increasing the risk for large, catastrophic wildfires.

“Catastrophic wildfires in our watersheds have impacts on so many levels,” said Christina Burri, a watershed scientist at Denver Water. “They are devastating for communities and the environment, but they also impact our water quality. When water runs through watersheds scorched by catastrophic fires, rainfall picks up sediment and ash which harms the water quality in our streams and reservoirs.”

Climate change makes it even more challenging to protect watersheds against catastrophic wildfires, she said. “This year is a perfect example. The wildfire season is longer, and the risks are greater.”

But Denver Water works with other agencies and local communities to mitigate those risks, Burri said.

From Forests to Faucets, a partnership between Denver Water and the U.S. Forest Service, focuses on forest treatment and watershed protection projects in priority watersheds critical to Denver Water’s water supply.

Through the Upper South Platte Partnership, Denver Water works with local landowners, government officials and other community members to manage forests and protect and improve the health of the watershed in counties where our water supplies flow.

And Denver Water planners work directly with communities to ensure public drinking water resources are kept safe from future contamination. Denver Water worked with the Colorado Department of Public Health and Environment and the Coalition for the Upper South Platte to create a source water protection plan for the Upper South Platte Watershed and implement that plan with Park, Douglas, Jefferson, and Teller counties.

A restored and thinned forest in Jefferson County in the Upper South Platte Watershed.

A restored and thinned forest in Jefferson County in the Upper South Platte watershed is much less susceptible to catastrophic wildfires.

“Our watersheds are the first filter through which our source waters run,” said Burri. “We have a really good source of water in our system, but if we don’t have a healthy filter for it, it causes more challenges down the line when we treat water. We have to make sure those filters are in the best shape possible.”

Preserving the environment and promoting high-quality water. Now that is cool, bro.

Are we talking about the ‘d’ word again?

Did a hot, dry summer push us closer to drought? Time to check in on the state of our water supply.  

By Steve Snyder

Barely a cloud in the sky at Denver's Cheesman Reservoir. In Colorado, the last few months have been warmer and drier than usual.

Barely a cloud in the sky at Denver’s Cheesman Reservoir. In Colorado, the last few months have been warmer and drier than usual.

Drought.

It’s one of the most doggone depressing and downright dreaded “d” words you can utter at a water utility.

Fortunately, Denver Water and most of Colorado have enjoyed a nice respite from drought recently. In fact, a string of cool, wet months turned last summer’s Drought Monitor map for our state practically monochrome.

But that was then, this is now. And drought is not a novel idea in Colorado.

Of course, there’s a difference between talking about a drought and actually being in one. So as we start a new water year, let’s review some facts about the state of our climate — and our current water supply.

  • So far this year, Denver’s temperature hit 90 degrees or higher on 55 days. The long-term annual average over the past three decades is only 33 days.
  • This year, the Denver metro area received 12.4 inches of precipitation. Compare that to the long-term annual average of 13.3 inches.
  • While those precipitation numbers are similar, consider when the moisture fell. From January through May, precipitation in our service area was 120 percent of normal. From June through September, that precipitation was only 60 percent of normal.
  • The latest Drought Monitor map for Colorado now shows areas of moderate drought in the state, along with much larger areas that are considered abnormally dry.
  • The three-month forecast for most of Colorado calls for above-average temperatures with only average precipitation.

We watch weather patterns closely because Denver Water gets nearly all of its water supply from mountain snowpack. We collect it as it melts in the spring, treat it and then distribute it to our customers, based on demand.

The highest demand comes in the summer with outdoor water use — and the hotter the summer, usually the greater the demand.

The latest Drought Map for Colorado shows the impact of our recent hot, dry weather. (Photo courtesy of United States Drought Monitor.)

The latest Drought Map for Colorado shows the impact of our recent hot, dry weather. (Photo courtesy of United States Drought Monitor.)

Typically, our reservoirs hit peak levels in late spring and early summer and drain to their lowest levels just before the next spring runoff. Then the cycle starts again.

So after weighing all of those factors, should we be discussing the dreaded “d” word again?

“Drought is always in the back of our minds because we live in a semi-arid climate,” said Lindsay Weber, senior demand planner at Denver Water. “But typically during the fall and winter months, we are looking at snowfall. We track our snowpack to get an idea of how much water it might yield in the spring. If we start to see a shortfall, we have a drought committee that will prepare an appropriate response.”

Right now, Denver Water’s water supply is in good shape. Systemwide, our reservoirs are at higher-than-normal levels for this time of year, thanks to cooler, wetter weather in 2015, along with continued efficient water use by our customers.

So while the short-term outlook is encouraging, most Colorado residents know we can never rest on our laurels, or in this case, our reservoir levels. Climate change, a growing population and a strain on our natural resources will only continue to put pressure on long-term planning for a sustainable water supply. The next drought could be right around the corner.

But for now, the “d” word isn’t front and center in most conversations at Denver Water. Unless of course, we are talking about our Denver Broncos defense. That’s a “d” word we know other people truly dread.

Floatin’ on the 4th: Making waves on the Blue River

Dillon Reservoir’s water managers help extend the whitewater rafting season while meeting customer needs downstream.  

By Jay Adams

 

 

Nothing says Fourth of July in Colorado like a day of rafting on a mountain river. Paddling through rapids is as much a tradition in our state as fireworks, hot dogs and apple pie.

Our nation’s birthday is one of the busiest days of the year for whitewater rafting. But there’s no rafting without rapids — and that’s where Dillon Reservoir comes in.

With a capacity of 257,304 acre feet, Dillon Reservoir in Summit County is Denver Water’s largest storage site, supplying 30 percent of Denver’s water. Water managers work to balance the demands of Denver customers while supporting the recreational economy on the Blue River and Dillon Reservoir.

“In the spring and early summer, Denver Water carefully manages outflows from Dillon Reservoir,” said Cindy Brady, water resource engineer at Denver Water. “We try to provide reliable and predictable rafting flows on the Blue River below Dillon Dam.”

Whitewater rafting through the spectacular alpine scenery beneath The Eagles Nest Wilderness area on the Blue River. Photo courtesy of Performance Tours Whitewater Rafting.

Whitewater rafting through the spectacular alpine scenery beneath The Eagles Nest Wilderness area on the Blue River. Photo courtesy of Performance Tours Whitewater Rafting.

In years with above-normal mountain snowpack, water planners gradually increase the outflow from Dillon to make room for the spring runoff that fills the reservoir. The approach minimizes high water through the town of Silverthorne and helps extend the rafting season.

“Instead of having a really high flow early on and then having it drop to an unraftable level, Denver Water manages the water so we have optimum flows as long as possible,” said Kevin Foley, president of Performance Tours Whitewater Rafting, sending rafters down class 3 whitewater trips on the Blue River for 30 years.

As Dillon Reservoir’s recreational role grew, Denver Water began working closely with Summit County and the rafting community to manage the river flows. “We work with the whitewater industry to understand their flow needs and communicate to them what to expect each year,” Brady said.

The best flows for rafting are when the river is running between 1,100 and 1,400 cubic feet per second, Foley said. “Knowing how much water is coming down is incredibly important when we plan our rafting season,” he said.

Outflows from Dillon Dam into the Blue River reached their highest level of the season at 1,490 cubic feet per second on June 15 and are expected to drop as the runoff slows and outdoor watering picks up in Denver.

“It’s a constant balancing act,” Brady said. “We always try to meet the interests of everyone to enhance the recreational experience.”

Releasing water in the middle of a drought?

California does it, and so do we. It’s all part of managing a complex water system.

By Dana Strongin

Even in times of severe drought, sometimes a water system has to know when to let go.

Consider the conundrum in water-challenged California, where operators recently doubled the amount of water flowing out of federally run Folsom Lake, a Northern California reservoir.

“You can’t hold on to every drop,” said Shane Hunt, a spokesman for the Bureau of Reclamation, which runs Folsom.

AnteroJune2015_close

Water drains out of Antero Reservoir in June 2015 as part of preparations to rehabilitate Antero Dam.

Why would a water system release such a precious resource? We put the question to Nathan Elder, water resource engineer at Denver Water.

“The main benefit of drawing a reservoir down early is to be able to control releases from the reservoir,” Elder said. From a system view, opening space in one reservoir may create the flexibility to fill all of the reservoirs during the runoff season.

Call it science or a miracle, we are blessed to have the gift of Mother Nature’s snows as our primary source of water.

Denver Water’s mountain collection system spans about 4,000 square miles and houses a lot of infrastructure — facilities that cannot all be online all of the time. Maintenance and improvement projects, such as upgrading the outlet works at Dillon Reservoir and rehabilitating Antero Dam, are critical to keep the system working well into the future.

Operating reservoirs requires careful thought — including balancing many other important considerations, such as water supply, safety, recreation, the environment and hydropower.

With all of the complexities our planners consider, they can count on one simple fact: Every spring brings warmer weather, and most of the mountain snow will melt. We need a place to put that water to store it for future use.

DillonMay2009_making_room

Dillon Reservoir sits low in May 2009, after operators released water to make room for runoff.

Dillon Reservoir offers a good example. In early February 2014, when Dillon was 94 percent full, we started to make room for the robust runoff expected with snowpack at 163 percent of normal. And in late January 2015, because the reservoir was 99 percent full and we had a healthy snowpack, we began to slowly lower the reservoir.

It’s starting to happen again this year. Dillon Reservoir is 93 percent full, and snowpack above it is 108 percent of normal. In late February we began letting out more water to slowly decrease the reservoir level and benefit hydropower production at the same time. It’s possible we could decide later to release water at a higher rate to make more room for runoff.

But it’s way too early to know for sure. Denver Water operators keep their eyes on the skies and weather forecasts so they can stay nimble if conditions change quickly.

Either way, releasing reservoir water is not necessarily a loss. “Water released from Dillon is used to generate hydropower,” Elder said. “If conditions present themselves, releases can be managed and timed to prolong rafting season on the Blue River.

“The water may not go to customer’s taps, but that does not mean it is not put to use.”

El Nino: Helping hand or just a lot of hot air?

Snow in Colorado. Rain in California. Is El Nino the cause, and can it keep the water coming?

By Steve Snyder

Too big to fail.

No, this isn’t about enormous financial institutions. We’re talking about the biggest, baddest El Nino weather pattern we’ve seen in years.

This year’s version of the warming surface water in the Pacific Ocean was supposed to blast much of California and other western states with potentially record-setting moisture. If you’re keeping up with climate news, California in particular could use the water.

This map of a typical El Nino weather pattern shows Colorado right on the edge of moisture impacts. (Courtesy: National Weather Service)

This map of a typical El Nino weather pattern shows Colorado right on the edge of moisture impacts. (Courtesy: NOAA)

And so far, so good, at least in terms of moisture content. But the key words are “so far,” as even this supersized El Nino hasn’t made a huge dent in the Golden State’s decade-long drought.

So why is Denver Water watching the weather in California so closely? One reason is that water resources for Colorado and California are closely linked. Any moisture California gets is good for Colorado and the entire Colorado River Basin.

We’ve seen a lot of moisture in Colorado this winter, too, and it has really helped our snowpack. But how much is our winter wonderland related to our warm-blooded friend in the Pacific?

“It’s difficult to credit El Nino for all of our weather this winter,” said Laurna Kaatz, climate adaptation program manager for Denver Water. “El Nino typically increases precipitation across the southwest, and our Rocky Mountains are right on the fringe of this area. So El Nino can influence our weather, but it’s not the only factor.”

It’s also difficult to predict what the rest of the winter and early spring will bring in terms of moisture for Colorado, as each El Nino pattern is different. But there are some historical patterns to study.

“Past El Nino cycles have usually brought moisture to Southern Colorado,” Kaatz said. “The three-month outlook calls for above-normal precipitation in Colorado, but nothing is certain here in terms of weather, given our location and topography.”

Of course, as long as the snow keeps piling up in our mountains, we don’t care if it’s El Nino or El-Nacho Libre causing the stir. We’ll take all we can get, especially with Colorado’s unpredictable weather.

Why Denver Water loves snow

Snow far, snow good: Winter snowpack off to strong start — where there’s snow, there’s water.

By Jay Adams

 

 

What’s good for skiers is good for reservoirs. If you’ve already hit a few powder days on the slopes this year, you know the winter of 2015-2016 is off to a snowy start in the mountains.

As of Feb. 16, the amount of snow in the Colorado and South Platte river basins stands at 110 and 114 percent of normal respectively for this time of year, according to the Natural Resources Conservation Service. This is good news for Denver Water, as the mountain snow in these two river basins is the primary source of our drinking water supply.

Denver Water caretaker Per Olsson snowshoes through the woods to access snow-measuring sites.

Keeping track of how much snow is in the mountains is a team effort. From January through May, our crews make a monthly trek into the wilderness and measure snow at 11 locations in Grand, Park and Summit counties. They hike, snowshoe, cross-country ski and ride in snowcats to reach our snow-measuring sites.

“It’s fun to see how much snow we are going to get every year,” said Per Olsson, Jones Pass caretaker. Olsson has been measuring snow at Denver Water for 25 years, including several locations in Grand County. “We’re hoping for a lot of snow this year, and so far it looks good.”

In late January, Olsson and Conor Peters, a water monitoring specialist, strapped on snowshoes and trudged through the forest for a monthly check of the snowpack at the base of Berthoud Pass near Winter Park.

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Olsson (left), and Conor Peters, measure snow density, depth and weight at the base of Berthoud Pass. Records of snow have been kept at the site since 1936.

Measuring snow requires more than just checking how much is on the ground. Olsson and Peters use a special tube to measure the depth, density and weight of the snow at seven locations on the Berthoud Pass snow-measuring site.

The courses provide water planners with eyes-on-the-ground information to compare 2016 numbers with snowpack levels dating back to 1936.

They use that information to determine the snow-water equivalent: a calculation of how much water is packed into the snow. “A general rule of thumb is that 12 inches of snow equals about 1 inch of water when it melts,” said water resource engineer Nathan Elder.

Denver Water also uses information collected by the Conservation Service’s automated snowpack telemetry weather stations, known as SNOTEL sites. The network of stations was established in 1979 and provides real-time snow information at locations across Colorado and the western U.S.

Olsson has worked at Denver Water for 25 years.

Olsson has worked at Denver Water for 25 years.

The manual and automated readings provide Denver Water’s planners with a picture of how much and what type of snow is in the mountains. They use the information to make predictions about how much water will end up in Denver Water’s reservoirs during the spring runoff.

Despite the strong start to the winter, planners don’t make early assumptions. “This year is looking good so far,” Elder said. “We like to see snow any time of year, but March, April and May are our snowiest and wettest months.”

Elder said it takes patience to see how the snowpack develops. “We don’t want to make any decisions about our supply this early,” he said. “We’ve still got a ways to go this winter and even though we are above normal now, weather conditions can change quickly.”

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