A look at the history of Dillon Reservoir

Dillon townsite prior to construction of Dillon Reservoir via Denver Water

Here’s a report from The Summit Daily (Deepan Dutta). Click through and read the whole thing. Here’s an excerpt:

The lecture, titled “Dillon, Denver and the Dam,” took place in the old Historic Park Chapel behind the museum, where every pew was filled and the audience spilled out of the door. Mather, a former president of the Summit Historical Society who has written 20 books about Summit County’s rich history and has a doctorate in physical geography, spoke to the capacity crowd on why the reservoir was built and the numerous challenges it faced being built…

The reservoir’s need was first realized in 1907, when the city of Denver realized it would require a lot more water as it grew. In 1913, Denver Water started buying water rights around Summit County, seeing the area’s natural geography as ideal for a reservoir.

“This was a huge catchment area,” Mather said. “You had a confluence of three streams, the narrowing of the valley north of Dillon, you would have gravity flow through the tunnel across the Continental Divide, and all were very important.”

Unfortunately, many benefits that were found in geography were lost to the local geology. There were numerous challenges in trying to find a place to put the dam, and once it was found a whole lot of earth-moving had to be done to artificially strengthen the foundation and ensure water would not start leaking under the dam.

Before constructing the dam itself, a core trench was dug 90 feet deep under the entire length of where the dam now stands, down to the bedrock. Another trench was dug into the bedrock itself, and then giant holes were dug into that trench 300 feet deep and filled with concrete. Suffice to say, the dam built on top of that foundation is well reinforced.

When the dam was finally completed in 1963, it stood 231 feet tall, 5,888 feet long and over 580 feet wide. Twelve million tons of fill was used to build the dam, with most coming from borrow pits in the reservoir area.

Aside from the dam, constructing the reservoir itself was a herculean endeavor itself. Given that the entire purpose of the reservoir is to impound water for use elsewhere, the reservoir needed to be lined and segregated from the ground [water].

That’s why a steel liner was installed to ensure the water stayed in the reservoir and didn’t get contaminated. The liner – a quarter-inch thick, highly polished steel – was pieced together at the bottom of what is now the reservoir in 30-foot long pieces.

There’s also the matter of managing overflow. That job goes to a morning glory spillway, which is basically a giant cement funnel at the dam’s maximum capacity height of 9,017 feet. All overflows fall into this spillway, which features fins at the top to prevent a whirlpool at the top, which would create air bubbles that can deteriorate the spillway’s cement.

Overflow water runs straight down the gullet of the spillway, which is 15 feet wide at its narrowest part, before turning 90 degrees and running into the Blue River through a 15-foot wide fixed-wing gate, which can be opened and closed to regulate water flow into the Lower Blue River.

Denver Water employees Rick Geise and Nate Hurlbut assisted in setting the plug, which helps prevent chunks of ice and snow from falling into the spillway. Photo credit: Denver Water

When fall comes and the reservoir is lowered, the spillway is no longer in use. Mather explained that since cold water sinks, the spillway can get iced up inside, damaging the concrete. To prevent this, Denver Water uses a crane to lift a giant “plug” — a 6-ton steel disc — and lower it into the spillway, preventing ice and debris build-up.

Mather described another key component of the entire reservoir system, the Roberts Tunnel. The 23-mile long tunnel, which when built was the second largest in the world, takes water from the reservoir in the West through a 10-foot wide pipe across the Continental Divide and down 174 feet of elevation to the eastern portal in Grant.

Mather said the construction of the tunnel began one month to the day before she was born, on September 17, 1942. Construction of the tunnel officially ended two months to the day after Mather graduated from college, when the eastern portal opened 22 years later, on July 17, 1964.

#Runoff news: Dillon Reservoir close to full, Roberts Tunnel off

Denver Water employees Rick Geise and Nate Hurlbut assisted in setting the plug, which helps prevent chunks of ice and snow from falling into the spillway. Photo credit: Denver Water
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From The Summit Daily News (Deepan Dutta):

Nathan Elder, water supply manager for reservoir owner Denver Water, reported Friday that the reservoir was just under a foot from being full, with 2,600 acre-feet of storage space remaining. Elder predicted the reservoir would fill in about two days.

The latest inflow data showed 2,219 cubic feet per second flowing into the reservoir, while 1,840 cfs is flowing out. Elder said that, while the dam wasn’t meant for flood control, the flows in the Lower Blue would be much stronger if the dam wasn’t there at all.

“We constantly try to balance inflows with outflows,” Elder said. “If the dam wasn’t there, flows below the reservoir would be close or at 3,000 cfs.”

Elder said the Roberts Tunnel, which channels water from the reservoir to the Front Range, was currently off and not bringing water to the Eastern Slope. Denver Water will continue adjusting flows for the reservoir to keep it at full capacity until Nov. 1, when the reservoir is lowered 3 feet to leave room for snow precipitation.

Elder said Denver Water has been conducting twice-daily briefings with county emergency officials, updating the forecast on flows into the Lower Blue. Summit County emergency director Brian Bovaird said that all tributaries in the county were at or just below “action stage,” or when county flooding preparations take effect.

Bovaird said there is a possibility Denver Water will increase flows below the dam to up to 1,900 CFS by this weekend, close to the highest flow recorded below the dam. However, he said there was good news from the National Weather Service, which predicted no heavy rain this weekend to push the rivers over the edge.

Bovaird said that emergency officials will start to get concerned if the outflows rise to 2,100 CFS. But for now, Bovaird said he didn’t expect any major flooding to occur when the peak flows finally peter out next week. Bovaird reported some “nuisance” flooding in Silverthorne’s South Forty neighborhood, but it did not cause any structural damage or threaten homes.

Bovaird added things were looking good at the Goose Pasture Tarn dam, which was built in Breckenridge in the ’60’s and has been a source of concern due to the potential for flooding or even collapse. Tenmile Creek, which approached flood stage a few weeks ago, peaked last week without any significant flooding or damage.

Headwater Hops Fest — Blue River Watershed Group, August 14, 2019

Join the Blue River Watershed Group for an evening of lakeside views and local-crafted brews. Learn how we are working to protect the mountain water that helps make our local beers and spirits so delicious.

Ticket includes unlimited tastings, commemorative glass, dinner, silent auction, and live music from Ms Amy & The Jet Set!

$25 advance tickets, $30 day of. Go to http://www.blueriverwatershed.org

#Runoff news: Tenmile Creek, Straight Creek and the Snake River all approaching flood levels

From The Summit Daily (Deepan Dutta):

The water is roaring across Summit County. Tenmile Creek, Straight Creek and the Snake River are all approaching flood levels as the great 2019 spring runoff rushes in with thunderstorms on the way this weekend…

Tenmile Creek is one of the best gauges of how powerful the runoff is. The stream is currently cresting at 3.88 feet, with overflows into low-lying areas in and west of Frisco beginning at 4.8 feet…

At 5 feet, Tenmile Creek is at flood stage. At that point, there will be minor flooding of roads and properties along Tenmile Creek. At 6.5 feet, or moderate flood stage, houses begin to flood. Major flood stage starts at 7.5 feet, with significant flooding in Frisco and on the westbound lane of Interstate 70.

Residents should take some comfort in knowing that Tenmile Creek never has gone above 5.14 feet, a mark set June 17, 1995. Frisco authorities have continued to warn residents about potential flooding, with town and county staff on standby in case banks get run over.

The Snake River is currently sitting at 2.7 feet, with flood mitigation action called for at 3.3 feet. The Snake’s record crest was set June 6, 1972, when it reached 3.88 feet. At 3.8 feet, Keystone begins to flood, but that level has been reached only twice since record keeping began there in the 1940s.

Straight Creek in Dillon is currently at 4.86 feet, with action stage at 5.3 feet and flood stage at 6 feet. That stage never has been reached in recorded history, with Straight Creek topping out at 5.78 feet June 17, 1995.

Water flows into and out of local reservoirs also are rapidly speeding up. On Friday, Green Mountain Reservoir started ramping up outflows into the Blue River. Starting at 800 cubic feet per second, the reservoir will increase flows by 50 cfs every two hours until it reaches 1,400 cfs at 4 a.m. Saturday. That flow will be maintained until further notice.

The increased flows are meant to support the Coordinated Reservoir Operations initiative which seeks to enhance spring water flows consistent with the Upper Colorado River Endangered Fish Recovery Program. The conservation program seeks to boost the number of humpack chub, razorback sucker, bonytail and Colorado pikeminnow populations in the Blue.

Further south, the Dillon Reservoir is rapidly filling up after space was made for runoff these past few weeks. Water is dumping into the reservoir at a rate of more than 2,100 cfs, with outflows into the Blue River under the dam reaching up to 700 cfs. The reservoir is currently 83% full and just 15 feet shy of reaching peak elevation.

From The Moab Times-Independent (Carter Pape):

Based on historical averages, the Colorado River typically peaks near Moab during the first week of June. This year the river is projected to peak later; a forecast from the National Weather Service showed the river could reach its maximum on June 15.

Regardless of whether the peak is already behind, the river is high this year. On Monday, June 10, the United States Geological survey measured nearly 40,000 cubic feet of water per second flowing through the Colorado near Cisco, roughly twice the average for this time of year. The National Weather Service has issued a flood advisory for the Colorado River near the Utah/Colorado state line in Mesa and Grand counties…

Farther upstream, the National Weather Service issued a flood advisory on June 11 between Grand Junction and the Utah state line as a result of the river nearing flood levels that morning.“ Minor low land flooding is expected with impacts along recreation trails already being experienced,” the Weather Service said in its flood advisory statement. “Water levels and flows along the Colorado River in Mesa and Grand counties will continue to increase due to the recent warm trend. River levels will stay high through the week…The water is swift, [it is] cold and contains debris and snags. Know your limits if recreating on or near the Colorado. A life jacket and proper equipment is a must. Smaller tributaries in the area are also running fast and cold.”

Down the river, the water has been higher than typical, but not a danger to areas in the floodplain. At its peak, the U.S. Geological Survey gauged the height of the river near Cisco to be over 14 feet this week…

Local Colorado River tributaries are also higher than typical for this time of year. Near the head of the Dolores River, the USGS measured the location’s highest instantaneous flow since 1987 at 4,360 cfs.

At Mill Creek, before the Sheley Diversion that flows into Ken’s Lake, a gauge measured an average flow rate of 88 cfs on June 8, three times the daily average for the same time of year.

As high as the waters may seem this week, they are far from a record for the area, which had much heavier flows historically due to a lack of damming upstream. In one day in 1884, more water flowed past Moab than the city has used since January 2000.

According to the USGS, the highest flow rate on record for the Colorado River at the gauging location near Cisco, just after the Dolores River junction, was measured on July 4, 1884. The flow rate that Independence Day was measured to be 125,000 cfs.

#Runoff news: @DenverWater is drawing down Dillon Reservoir in anticipation of big #snowpack melting-out

Grays and Torreys, Dillon Reservoir May 2017. Photo credit Greg Hobbs.

From the Summit Daily (Deepan Dutta):

This year, instead of supplying helicopters with water to dump on fires, Denver Water is draining water from Dillon Reservoir in anticipation of runoff, which is expected to really begin coming down in the next few weeks.

“This year being a high snowpack year, we know there’s going to be a lot of water getting into the reservoir,” Denver Water supply manager Nathan Elder said. “We’re trying to have enough space to catch that runoff while providing for safe outflows to the Blue River below the reservoir.”

[…]

At the moment, the reservoir — which is the main drinking water supply for 1.4 million people in the Denver metro area — is 75% full with 192,554 acre-feet of water. When full, the reservoir holds 257,304 acre-feet. An acre-foot of water would cover an area the size of an acre 1-foot deep. Given the current estimate for runoff volume, there will be more than enough water to fill it.

“The forecasting for the rest of June and July project a volume of anywhere from 169,000 acre-feet to 211,000 acre-feet coming into the reservoir,” Elder said. “That’ll fill it, but we’re probably not going to fill it until the Fourth of July to make sure we’re past that peak-inflow time.”

Elder said peak inflow to the reservoir is expected to start about a week later this year than usual, which also means Summit’s two marinas in Dillon and Frisco will have to wait before the reservoir is full enough for boating. However, boaters should have a lot more time for play this year compared with last, when boat ramps were retracted weeks before they normally would be due to low water.

“Typically, every year we target June 18 to be at 9,012-foot elevation needed for both marinas to be completely operational, but it’s going to be a little delayed this year,” Elder said. “But while the boating season might be shortened by a week on the front end, on the tail end, it should last quite a bit longer.”

The delay also means local emergency officials will be watching streamflows longer into the month, looking to spring into action if Tenmile Creek, Straight Creek or the Blue River approach the verge of flooding.

Current two-week projections show all three waterways approaching “action stage,” the threshold at which the towns and county are called to start flood mitigation preparations, by June 15.

Summit County’s director of emergency management Brian Bovaird said he closely has been watching the forecasts for flooding. That is opposed to last June when Bovaird, who recently had gotten the job as emergency director, was given a literal trial by fire.

“It’s like picking your poison,” Bovaird said. “Last year, it was wildfire. This year, it’s flooding. We’re expecting heavy runoff moisture, which is good for wildfire but makes us uneasy about the flooding risk.”

Barker Reservoir

From Patch.com (Amber Fisher):

Barker Dam’s scheduled spill is expected to begin over the next few days, officials said. Each spring as temperatures warm, runoff from melting mountain snow increases stream flows. Before peak stream flows occur at lower elevations, like in the City of Boulder, mountain reservoirs must first fill and start spilling, officials said.

“This is a normal and expected event that will increase flows in Boulder Creek throughout the city,” The City of Boulder said in a statement.

The Barker Dam spill normally occurs between mid May to late June, but is dependent on weather, snowpack and early spring reservoir levels. This spring, cool temperatures and continued snow accumulation have delayed snowmelt runoff, the city said.

From KJCT8.com (Nikki Sheaks):

The waters of the Gunnison River are currently at 10.7 feet. It has passed the bankfull stage. This means some water is beginning to spill out into the floodplain. The floodplain is the low-lying area next to the river. The Gunnison’s Flood stage is at 13 feet. It’s expected to rise near 10.8 feet by Saturday.

Orchard Mesa and Whitewater are under the current advisory.

Parts of the Colorado River are rising, but it’s not under an advisory. The Colorado River near Loma is nearing bankfull. According to data from a National Weather Service gauge near the state line, water levels are at about 10.5 feet and are expected to rise to 12.5 by Saturday afternoon.

PHOTO CREDIT: McKenzie Skiles via USGS LandSat
The Great Salt Lake has been shrinking as more people use water upstream.

From The Deseret News (Amy Joi O’Donoghue)

The south arm of the Great Salt Lake is up by 2.5 feet since December and its north arm is 2 feet deeper thanks to the wet water year, and the Western Hemisphere’s largest saltwater lake will take on even more water in the weeks to come.

“It’s a pretty good jump so far, but we’re not done yet,” said Todd Adams, deputy director of the Utah Division of Water Resources.

The highest elevation snowpack has yet to melt, and with most reservoirs brimming, that water will bypass those storage infrastructures and help quench the thirsty saltwater body…

Water managers along the Wasatch Front will be keeping their eye on stream flows and reservoir levels to keep enough storage going into the summer and time releases into rivers to hopefully avoid flooding.

While most reservoirs are already full, Echo above East Canyon sits at just 49 percent of capacity and Rockport sits at 78 percent, ready to take on snowmelt.

“We could have filled it (Echo) twice this year,” said Tage Flint, general manager of the Weber Basin Water Conservancy District. “The peak flows have not occurred yet coming out of the Uinta Mountains coming down the Weber River, so we are purposefully leaving Rockport down some and Echo down more to use them as shock absorbers to take those big flows.”

Much of that extra water will be sent on downstream to the Great Salt Lake…

The lake is critical to wildlife, multiple industries, recreation interests and more, contributing $1.3 billion into Utah’s economy and drawing tourists from all over the globe.

It serves as the Pacific “flyway” for thousands of migratory birds and supports a $57 million brine shrimp industry…

Mike Styler, who recently retired as executive director of the Utah Department of Natural Resources, said maintaining the viability of the Great Salt Lake will be one of the critical challenges the state faces going into the future.

He stressed that as agricultural water gets converted for urban use in Weber and Davis counties and reuse of waste water becomes more popular, that threatens to dry up marshes and wetlands that support the lake.

The Great Salt Lake has an average depth of 16 feet, covers 1,700 square miles during an average year and is two to seven times saltier than the ocean.

Frisco councillors approve water rate increase

From the Summit Daily News (Sawyer D’Argonne):

Following months of discussion the town of Frisco finally pulled the trigger on a new water rate structure, along with increased tap fees, in hopes of incentivizing water conservation while keeping a well-maintained fund balance for future capital improvements.

The ordinance passed in a split 6-1 vote, with Councilman Dan Fallon as the lone dissenter. The ordinance should see a second reading during the council’s next meeting in early June.

Prior to this year, the last time Frisco completed a water rates study was in 2006 and the scheduled rate increases were in effect until 2016, meaning the town hasn’t increased its water rates in more than two years. In November last year, the council asked staff to complete an in-house five-year study on the rates, resulting in the new ordinance.

The town landed on a base water rate of $45 a quarter, on top of an escalating fee structure wherein the more water a consumer uses, the more they’ll have to pay. The structure is organized so that on top of the base rate, customers will pay $1.12 per 1,000 gallons for those using up to 8,000 gallons; $2.24 per 1,000 gallons for those using between 8,000 and 16,000 gallons; $4 per 1,000 gallons for those using between 16,000 and 50,000 gallons; and $5 per 1,000 gallons for those using more than 50,000 gallons a quarter.

While the new rate structure was easily accepted within the council, other language within the ordinance was more heavily scrutinized, with council members going back and forth on proposed annual increases in service fees and usage rates…

Ultimately the council voted to move forward with an annual 5% rate increase over the next five years, which would allow the town to maintain an estimated $2.38 million fund balance through 2024, as opposed to a $2 million balance under a 3% annual increase. Town officials said they would look into potential programs to help subsidize capital costs for businesses looking to improve their water fixtures on Fallon’s suggestion.

The town then turned the discussion to increases in tap fees, hoping to create fees more competitive with the surrounding communities, without undermining developers who already have projects in the works in town. Frisco currently charges a tap fee of $4,300, while Breckenridge, Silverthorne and Dillon all currently have tap fees in excess of $7,500.

“In fairness to people that have done their due diligence, I don’t want to see a big increase right away,” said Councilwoman Melissa Sherburne. “It’s on us that we kept it so low for so long. We need to be fair to the people who do business with us. I certainly support the increase, but we need something incremental over the years to get up to that goal of market standard.”

The council finally settled on an increase to $5,000 per tap starting on Jan. 1, 2020, followed by a 10% annual increase every October. If the council chooses to pass the ordinance on second reading, the new water rate structure will go into effect on Oct. 1.

Frisco

#Runoff news: Folks are keeping an eye on streams as the #snowpack starts to melt out

Ten Mile Creek via ColoradoFishing.net

From TheDenverChannel.com (Jason Gruenauer):

Several towns and counties in Colorado are preparing for flooding after a snowy winter and several spring snowstorms have led to the state’s best snowpack in eight years, which is now on the verge of melting into runoff…

Take the above-average snowpack, add in historic avalanches that deposited debris in Tenmile Creek, and the town of Frisco wants to be ready for potential spring flooding. That’s why they’re taking extra steps this year to prepare.

“Are we sounding the alarm at this point? No, but we’re preparing,” said Frisco’s communications director Vanessa Agee.

Aerial shots of the avalanche areas show full trees, branches, large rocks, sediment, and snow still covering the recreation path that runs along I-70 and partially in the creek. That waterway eventually flows right through downtown Frisco.

The Frisco Public Works Department is inspecting the creek’s street crossings twice a day to look out for and remove any debris built up in the creek, and the town has staged a construction backhoe along Main Street near Tenmile Creek in case any backups happen. Sandbags are also being offered to residents, as they are every year…

Summit County says they are prepared to respond to flooding if it happens. A statement from a spokesperson read in part: “In the case of a significant flooding event anywhere in Summit County, we will establish a fire-rescue and law-enforcement incident command to respond to and manage the event.”

[…]

Frisco residents can pick up sandbags at the Public Works building (102 School Road) Monday through Friday from 8 a.m. to 4 p.m. The first 100 bags per lot are free, and are 25 cents apiece beyond that.

But residents are asked to fill their own sandbags at three piles set up throughout the town: 6th Ave./Galena Street; Madison Ave./Sunset Dr. or the Public Works shop on School Road. Once residents are done using the bags, the town is asking people to return to the sand back to the piles…

The confluence of Henson Creek (left) and Lake Fork Gunnison River (right, against the wall) in Lake City, Colorado. By Jeffrey Beall – Own work, CC BY 4.0, https://commons.wikimedia.org/w/index.php?curid=73852697

Hinsdale County, in central Colorado, held community meetings earlier this week to discuss evacuation plans, with flooding expected to hit the county seat of Lake City in coming weeks.

Avalanches this winter and spring sent large amounts of trees, rocks and earth into Henson Creek and the Lake Fork River, which runs through town.

When [the log and ice jams] release it could cause extensive damage to the town and the local infrastructure,” the Mineral County Sheriff’s Office wrote on its Facebook page.

Combined with typical runoff that happens each year, the county says it expects flooding to occur as the waterways become backed up with water. Henson Creek Road and Lake Road are closed at certain points until further notice, the county said.