As the runoff continues to subside, Reclamation believes it is necessary to further reduce flows in the Gunnison River below the Aspinall Unit. The Colorado Basin River Forecast Center is showing inflow to Blue Mesa continuing to drop from the current level of around 5,000 cfs to 2,100 cfs by mid July. The Uncompahgre Valley Water Users, who had reduced diversions through the Gunnison Tunnel a week ago because the Uncompahgre River was filling their needs, are now in need of filling the Tunnel. To facilitate the filling of Blue Mesa Reservoir, Reclamation will not be matching their increased diversions, which will take place starting on Thursday, June 30th, with increased releases from the Aspinall Unit. This will result in a flow reduction in the Gunnison River of approximately 200 cfs bringing flows in the Canyon and Gorge to around 1,100 cfs as measured at the gage below the Gunnison Tunnel. We know this is inconsistent with information previously provided, but hydrologic conditions are constantly changing and we must react to current circumstances and forecasts.
The heat, the lingering snow pack and the resulting nightly inflow peaks to Ruedi Reservoir could make for an interesting holiday weekend.
We anticipate that over the July 4th weekend, we will finish the fill at Ruedi. However, inflows at night are not ebbing off. Instead, the heat is bringing more of the high mountain snow pack on downstream. While we are diverting a full Boustead Tunnel to Turquoise Reservoir near Leadville for the Fryingpan-Arkansas Project, a significant amount of snow melt run-off is still coming into Ruedi, peaking at night around 1300 cfs.
Consequently, to try and stay ahead of the peaks while we still have some space in the reservoir, today we bumped releases up another 50 cfs. After this afternoon, the gage below the dam will read about 883 cfs. However, once the reservoir fills, we will have to send on downstream whatever nightly inflow peaks the reservoir receives.
We are coordinating with the Town of Basalt and local responders just in case we have releases over 950 cfs.
Tomorrow, Thursday June 30, we will be increasing the releases from Green Mountain Dam to the Lower Blue River. We will be bumping up to 1800 cfs. This change will be made in two stages; the first increase of about 150 cfs will be in the morning. The second increase of another 150 cfs will be in the afternoon. The 1800 cfs release will most likely be in place through the 4th of July holiday weekend.
From email from Reclamation (Kara Lamb):
With the high temperatures the last few days, nightly inflows to Lake Estes have been up and down. Peaks to Lake Estes continue to fluctuate between 900-1300 cfs. As a result, we are adjusting the release from Olympus Dam to the Big Thompson Canyon about every other day. Late tonight, June 29, releases to the canyon will jump up from 650 cfs to 790 cfs.
Here’s the link to the report from the United States Geological Survey (William Battaglin/Lauren Hay/Steve Markstrom). Here’s the abstract:
The mountainous areas of Colorado are used for tourism and recreation, and they provide water storage and supply for municipalities, industries, and agriculture. Recent studies suggest that water supply and tourist industries such as skiing are at risk from climate change. In this study, a distributed-parameter watershed model, the Precipitation-Runoff Modeling System (PRMS), is used to identify the potential effects of future climate on hydrologic conditions for two Colorado basins, the East River at Almont and the Yampa River at Steamboat Springs, and at the subbasin scale for two ski areas within those basins.
Climate-change input files for PRMS were generated by modifying daily PRMS precipitation and temperature inputs with mean monthly climate-change fields of precipitation and temperature derived from five general circulation model (GCM) simulations using one current and three future carbon emission scenarios. All GCM simulations of mean daily minimum and maximum air temperature for the East and Yampa River basins indicate a relatively steady increase of up to several degrees Celsius from baseline conditions by 2094. GCM simulations of precipi- tation in the two basins indicate little change or trend in precipitation, but there is a large range associated with these projections. PRMS projections of basin mean daily streamflow vary by scenario but indicate a central tendency toward slight decreases, with a large range associated with these projections.
Decreases in water content or changes in the spatial extent of snowpack in the East and Yampa River basins are important because of potential adverse effects on water supply and recreational activities. PRMS projections of each future scenario indicate a central tendency for decreases in basin mean snow-covered area and snowpack water equivalent, with the range in the projected decreases increasing with time. However, when examined on a monthly basis, the projected decreases are most dramatic during fall and spring. Presumably, ski area locations are picked because of a tendency to receive snow and keep snowpack relative to the sur- rounding area. This effect of ski area location within the basin was examined by comparing projections of March snow-covered area and snowpack water equiv- alent for the entire basin with more local projections for the portion of the basin that represents the ski area in the PRMS models. These projections indicate a steady decrease in March snow-covered area for the basins but only small changes in March snow-covered area at both ski areas for the three future sce- narios until around 2050. After 2050, larger decreases are possible, but there is a large range in the projections of future scenarios. The rates of decrease for snow- pack water equivalent and precipitation that falls as snow are similar at the basin and subbasin scale in both basins. Results from this modeling effort show that there is a wide range of possible outcomes for future snowpack conditions in Colorado. The results also highlight the differences between projections for entire basins and projections for local areas or subbasins within those basins.
The original project budget in 2007 was $6.19 million. An analysis of city records shows that increases in the budget for the pipeline makes up $1.19 million of the difference between the 2007 budget at the current requested budget authority.
The pipeline, which was mostly constructed last summer, would feed up to 52-cubic-feet per second of water into a hydroelectric generator located in the proposed “energy center” under the Castle Creek Bridge. The pipeline was originally budgeted for $1.9 million, meaning it’s cost have risen by about one-third. The city is also installing the pipeline as a precautionary measure, as it can serve as an “emergency drainline” to empty the reservoir should it ever get too full. Thomas Reservoir stores water for the municipal consumption and is located above the water treatment plant on Doolittle Drive, near the Aspen Valley Hospital.
The cost of the pipeline increased because of challenges encountered during construction, city utilities director David Hornbacher said. The alignment had to be rerouted numerous times to get around utility lines the city didn’t know were there, and the work had to be modified as required by a state permit, he said…
While most of the hydro plant’s budget overruns to date have been driven by hard costs, the big variable in ongoing expenditures is the federal permitting process.
The city recently said it would withdraw its controversial “conduit exemption” application in favor of going for the more standard small project license from the Federal Energy Regulatory Commission (FERC). The conduit exemption — which would have required a less-stringent environmental review — was based on the premise that the plant would be part of the municipal water system because it would be attached to the pipe ostensibly put in to drain Thomas Reservoir.
The FERC license requires an environmental assessment, requiring more time and money than the city had originally planned. The formal license application is expected to be submitted this summer.
More coverage from Andre Salvali writing for The Aspen Times. From the article:
“I’ve been in Aspen long enough to know the truism, ‘to delay is to deny,’ ” Aspen Mayor Mick Ireland said, in reference to one speaker’s idea that the city should switch gears and explore other ways of tackling the project.
“I think there are opponents of this project who absolutely, under no circumstance, want to see it happen. The strategy in Aspen has traditionally been, ‘Well, we’ll get a new council in two years and we’ll get a new outcome.’ And we have had things in Aspen that should have been done 30 or 40 years ago because of the strategy of delay.”
Ireland and others were participating in “Hydropower in Aspen” at the Aspen Institute’s Paepcke Building. The presentation and panel discussion, which allowed questions from the audience, was hosted by the Western Rivers Institute, a Carbondale-based nonprofit that advocates healthy rivers and ecologically responsible development of hydropower…
Earlier in the forum, Ireland said the city’s plans respect the ecosystems of Castle and Maroon creeks. He said the renewable-energy project will be another way in which Aspen sets an example for other communities by working to reduce the carbon footprint and its dependency on coal-generated power.
Here are the notes from this week’s webinar via the Colorado Climate Center. Here’s a preview:
All of the major reservoirs in the UCRB have experienced rapid storage increases in June. Daily inflows into Flaming Gorge, Blue Mesa, and Lake Powell are all well above their averages for this time of year. Inflows into Navajo have dipped below their average for this time of year. Lake Powell has seen large increases in volume and is now at 80 of average. It is projected that Lake Powell’s elevation will continue to rise through late July — projected elevation levels would be the highest they’ve been since October 2001.
The closure will took effect at 8 a.m Tuesday, and encompasses the North Saint Vrain River from Apple Valley Road at County Road 71 through the Town of Lyons, and the South Saint Vrain from Old South St. Vrain Road to the confluence with the North Saint Vrain to the Lyons eastern town limit…The closure includes watercraft such as rafts, belly boats, and inner tubes from floating in the river. Violations of the closure are a class 2 petty offense and can result in a $50.00 fine. There is a specific exemption for kayaks and whitewater canoes, which are permitted.
Here’s a report from Chris Woodka writing for The Pueblo Chieftain. Click through for the before and after construction photos. Here’s a excerpt:
A 75-foot hole is being dug down to bedrock in the narrow shale arroyo below where the North Outlet Works will be installed later this year. Much of the work is within the federal security boundary that protects the dam, so workers are under 24-hour surveillance by armed guards. To the south, water is gushing mightily out of all three outlets on the face of the dam. The workers are protected by a coffer dam made from more than 300 giant bags, each filled with 2 tons of sand. It seems safe enough, although work already is about 35 feet below the water level and getting deeper. Soon, a ramp will be built to get equipment in and out. For now, if the coffer dam should fail, a 220-ton crane is standing by to pluck out the track hoe and loader in the hole. For the workers, it would mean a mad dash for a ladder that leads to safety…
“We found a buffalo skull,” said MWH engineer Greg Minnick, when asked whether anything unusual has been encountered. “Other than that, just a lot of wet dirt.”[…]
The digging at the base of the dam should be complete by early July. About 6,000 cubic yards of material will have been removed. About 350 to 400 truckloads of concrete will be placed in the hole to form an apron about 30 feet from the dam. The rest of the area will be back-filled. Minnick said about 15 to 16 trucks a day will come to the site, pouring in the early morning hours to take advantage of lower temperatures. That work should be finished in August. After that, a stainless steel sleeve will be placed inside the dam outlet. It will connect to a Y-shaped pipe that will supply both the river — at the same rate as the old outlet did — and the Juniper Pump Station to be built about one-quarter mile to the northeast. The first section of pipe from the North Outlet Works will taper out to a maximum of 90 inches in diameter, separating into a 48-inch line that will supply Pueblo West with up to 18 million gallons of water daily, and a 66-inch line that will deliver up to 78 million gallons daily to El Paso County. Part of that pipe will have to be installed through the rocky formations at the base of the dam, and engineers are now working on a design and work plan to do that without causing vibrations that could disturb the dam, Tunnah said.
More Southern Delivery System coverage here and here.
The more than $1.1 million project to replace century-old clay sanitary sewer pipes with new pipes, while also installing a new storm sewer from 10th Street to Fourth Street, started May 16 and is expected to be complete Aug. 1. “We’re pretty much right on schedule with the whole project,” Steamboat Public Works Director Philo Shelton said. “Obviously, we’ve had a good run of weather.” Shelton said Native Excavating crews have reached Sixth Street. The project is being done two blocks at a time…
The project is being paid for through an $11.9 million loan, bonds issued by the Colorado Water Resources and Power Development Authority, to fund infrastructure projects during the next two to three years. Shelton said other projects include a water main replacement at 13th Street that will take place this fall and construction of a 1 million gallon water storage tank for the west side of Steamboat next year. The bonds will be repaid through revenue from the city’s utility fund, which includes a multiyear increase to water and sewer rates that the City Council approved in September, Steamboat Finance Director Deb Hinsvark said.