@USGS: Numerical Model Simulations of Potential Changes in Water Levels and Capture of Natural Discharge From Groundwater Withdrawals in Snake Valley and Adjacent Areas, Utah and Nevada

Click here to read the report. Here’s the abstract:

The National Park Service (NPS) and the Bureau of Land Management (BLM) are concerned about cumulative effects of groundwater development on groundwater-dependent resources managed by, and other groundwater resources of interest to, these agencies in Snake Valley and adjacent areas, Utah and Nevada. Of particular concern to the NPS and BLM are withdrawals from all existing approved, perfected, certified, permitted, and vested groundwater rights in Snake Valley totaling about 55,272 acre-feet per year (acre-ft/yr), and from several senior water-right applications filed by the Southern Nevada Water Authority (SNWA) totaling 50,680 acre-ft/yr.

An existing groundwater-flow model of the eastern Great Basin was used to investigate where potential drawdown and capture of natural discharge is likely to result from potential groundwater withdrawals from existing groundwater rights in Snake Valley, and from groundwater withdrawals proposed in several applications filed by the SNWA. To evaluate the potential effects of the existing and proposed SNWA groundwater withdrawals, 11 withdrawal scenarios were simulated. All scenarios were run as steady state to estimate the ultimate long-term effects of the simulated withdrawals. This assessment provides a general understanding of the relative susceptibility of the groundwater resources of interest to the NPS and BLM, and the groundwater system in general, to existing and future groundwater development in the study area.

At the NPS and BLM groundwater resource sites of interest, simulated drawdown resulting from withdrawals based on existing approved, perfected, certified, permitted, and vested groundwater rights within Snake Valley ranged between 0 and 159 feet (ft) without accounting for irrigation return flow, and between 0 and 123 ft with accounting for irrigation return flow. With the addition of proposed SNWA withdrawals of 35,000 acre-ft/yr (equal to the Unallocated Groundwater portion allotted to Nevada in a draft interstate agreement), simulated drawdowns at the NPS and BLM sites of interest increased to range between 0 and 2,074 ft without irrigation return flow, and between 0 and 2,002 ft with irrigation return flow. With the addition of the proposed SNWA withdrawals of an amount equal to the full application amounts (50,680 acre-ft/yr), simulated drawdowns at the NPS and BLM sites of interest increased to range between 1 and 3,119 ft without irrigation return flow, and between 1 and 3,044 ft with irrigation return flow.

At the NPS and BLM groundwater resource sites of interest, simulated capture of natural discharge resulting from withdrawals based on existing groundwater rights in Snake Valley, both with and without irrigation return flow, ranged between 0 and 100 percent; simulated capture of 100 percent occurred at four sites. With the addition of proposed SNWA withdrawals of an amount equal to the Unallocated Groundwater portion allotted to Nevada in the draft interstate agreement, simulated capture of 100 percent occurred at nine additional sites without irrigation return flow, and at eight additional sites with irrigation return flow. With the addition of the proposed SNWA withdrawals of an amount equal to the full application amounts, simulated capture of 100 percent occurred at 11 additional sites without irrigation return flow, and at 9 additional sites with irrigation return flow.

The large simulated drawdowns produced in the scenarios that include large portions or all of the proposed SNWA withdrawals indicate that the groundwater system may not be able to support the amount of withdrawals from the proposed points of diversion (PODs) in the current SNWA water right applications. Therefore, four additional scenarios were simulated where the withdrawal rates at the SNWA PODs were constrained by not allowing drawdowns to be deeper than the assumed depth of the PODs (about 2,000 ft).

In the constrained scenarios, total withdrawals at the SNWA PODs were reduced to about 48 percent of the Unallocated Groundwater portion allotted to Nevada (35,000 acre-ft/yr reduced to 16,817 acre-ft/yr or 16,914 acre-ft/yr, without or with irrigation return flow, respectively), and about 44 percent of the full application amounts (50,680 acre-ft/yr reduced to 22,048 acre-ft/yr or 22,165 acre-ft/yr, without or with irrigation return flow, respectively). This indicates that the SNWA may need to add more PODs, or PODs in different locations, in order to withdraw large portions or all of the groundwater that has been applied for.

At the NPS and BLM groundwater resource sites of interest, simulated drawdown resulting from the addition of the constrained SNWA withdrawals applied to the Unallocated Groundwater amount ranged between 0 and 290 ft without irrigation return flow, and between 0 and 252 ft with irrigation return flow. With the addition of the constrained SNWA withdrawals applied to the full application amounts, simulated drawdowns at the NPS and BLM sites of interest ranged between 0 and 358 ft without irrigation return flow, and between 0 and 313 ft with irrigation return flow.

At the NPS and BLM groundwater resource sites of interest, with the addition of the constrained SNWA withdrawals applied to the Unallocated Groundwater amount, simulated capture of 100 percent of the natural discharge occurred at five additional sites without irrigation return
flow, and at two additional sites with irrigation return flow (in addition to the four captured from existing water rights both with and without irrigation return flow). With the addition of the constrained SNWA withdrawals applied to the full application amounts, simulated capture of 100 percent occurred at six additional sites both with and without irrigation return flow.

“Our biggest project yet … on america’s most important river” — @COWaterTrust

The 15-Mile Reach is located near Grand Junction, Colorado

From the Colorado Water Trust (Andy Schultheiss):

You’ve been hearing a lot from us lately about a project on the notoriously troubled part of the Colorado River near Grand Junction called the 15-Mile Reach.

You’ve been hearing about it because we’re so excited about the potential impact, and proud of the diverse collaborations involved.

If you’ve missed it, here are the cliff notes:

  • The 15-Mile Reach is a stretch of the Colorado River known for flows that fall so low they can fail to support native federally endangered fish species. Flows often fall low twice yearly—in early spring and in late summer through early fall (spring because the snow that feeds rivers has not yet begun to melt, and Fall because it is the driest part of the year).
  • Just upstream of the 15-Mile Reach is the Grand Valley Power Plant (GVPP) – which is operated by our partners, Grand Valley Water Users Association (GVWUA) and Orchard Mesa Irrigation District (OMID). It’s a hydropower plant that was built in the 1930s.
  • GVWUA and OMID have senior irrigation water rights, and they also divert water for use in the power plant that returns to the Colorado River just upstream of the 15-Mile Reach. Which is very good for the river, as well as the local electrical grid.
  • Colorado Water Trust, GVWUA, and OMID recently completed an innovative agreement to allow us to buy water upstream to be delivered to the GVPP. That means our water can be delivered to the plant, used to generate hydropower, and then returned to the Colorado River during times when the 15-Mile Reach is in need. The aim is to keep the river at healthy flows to support native fish passage and spawning habitat.
  • Well here’s what’s new! We just did it! Last week!

    You may be thinking, well, wasn’t this a particular wet year? Why was the river in need?

    We didn’t think it was going to be, either. But as you’re probably aware, Colorado can really throw curveballs with its weather, and those curves are breaking more and more lately.

    Despite a promising water year, with snowpack levels not seen since at least 2011, and a wet early Summer on top of it, the Colorado and many other rivers in the state (including the Yampa, another of our top priorities) suffered severely decreased flow starting around Labor Day, due to a very hot, dry August. Even the GVPP wasn’t getting enough water to operate to its current capacity. We had the legal agreement in place, and we had money from our annual RiverBank celebration and from the generous folks at Coca Cola to buy water in the Colorado, so why not use it now?

    By purchasing water (that is owned by the Colorado River District, so a big shout-out to those folks as well for the very fast turnaround) from a nearby reservoir, we helped to boost flows in the 15-Mile Reach and generated clean electricity for six days. Our releases complemented the water dedicated to the river by the U.S. Fish and Wildlife Service’s Recovery Program and the Historic Users Pool, a group of western Colorado water users that release water from Green Mountain Reservoir. We’re now working on long-term funding for these purchases, from Coca Cola and others, and in cooperation with the U.S. Fish and Wildlife Service, the Colorado River District, and of course our two water user partners, we hope to help keep the river healthy for many years to come. Thanks as well to our crucial project partner the Walton Family Foundation, which originally suggested the idea and supported its development.

    Projects like 15-Mile Reach are what drives us here at the Water Trust. The problems we address are complex, politically and technically challenging, and getting more so. The idea that a “wet” year could turn into a semi-emergency because of 45 days or so of dry heat would have been remarkable fifty years ago. These days? Not really that surprising. But this is the challenge we face, and we get excited by finding creative ways to meet them that benefit multiple river users.

    When flows decline, which we all expect in the years to come because of the changing climate and growing population, the need to share our water becomes even more important. And harder to arrange. But that’s the Water Trust’s sweet spot, and we’re happy to be able to do it on that most American of rivers, the Colorado.

    Upper Colorado River Endangered Fish Recovery Program

    @EPA deletes residential areas in north #Denver from #Superfund list

    Map view via DenverGov.org

    Here’s the release from the Environmental Protection Agency (Lisa McClain-Vanderpool):

    Milestone at Vasquez Boulevard/ Interstate 70 Superfund site reflects completion of residential cleanups for lead and arsenic

    On September 20th, the U.S. Environmental Protection Agency (EPA) finalized a partial deletion of the Vasquez Boulevard/Interstate 70 (VB/I-70) Superfund site in Denver, Colorado from the National Priorities List (NPL) of the nation’s most contaminated sites. EPA and the Colorado Department of Public Health and Environment have determined that all required cleanup activities are complete in the area proposed for deletion.

    “The deletion of this area from the Superfund list represents the culmination of two decades of efforts to sample, clean up and restore residential yards affected by lead and arsenic contamination in north Denver,” said EPA Regional Administrator Gregory Sopkin. “We share this residential cleanup achievement with our partners at the State of Colorado, the City of Denver and the local community.”

    Under the Trump administration, EPA’s Superfund program has reemerged as a priority to fulfill and strengthen the agency’s core mission of protecting human health and the environment. In fiscal year 2018, EPA deleted all or part of 22 sites from the Superfund’s NPL, the largest number of deletions in one year since FY 2005 and a significant increase over the past few years.

    EPA is finalizing the deletion of the residential area of the VB/I-70 Superfund site, also called Operable Unit 1, based on a determination that no further action is needed to protect human health and the environment. EPA received public comments on the proposed deletion from February 6th to April 8th 2019 and prepared a responsiveness summary to those comments, which is available online at http://www.regulations.gov (Docket # EPA-HQ-SFUND-1999-0010) or at the Valdez-Perry Branch Library, 4690 Vine Street, Denver, Colo.

    The area will continue to be subject to regular EPA review for protectiveness. EPA will continue to address contamination concerns at remaining portions of the VB/I-70 site, which includes the locations of two former smelters. EPA proposed the deletion of Operable Unit 1 earlier this year and concluded a public comment period in March.

    The VB/I-70 Superfund site includes four square miles in north Denver, including the Cole, Clayton, Swansea/Elyria, southwest Globeville and northern Curtis Park neighborhoods. EPA placed the site on the NPL in 1999 due to metals contamination, mainly lead and arsenic, associated with historic smelter operations in the area. In 2003, EPA selected a remedy for residential properties that included extensive soil sampling, soil removal, and a community health program. In completing that work, EPA has sampled more than 4,500 residential yards and cleaned up more than 800.

    Historically, the affected north-Denver neighborhoods were a major smelting center for the Rocky Mountain West. Two smelting plants—Omaha & Grant and Argo—operated at the site for varying lengths of time, beginning as early as the 1870s, refining gold, silver, copper, lead and zinc. As a result, heavy metals were deposited in area soils at levels that, in some cases, posed a health risk to residents. Groundwater impacted at the former smelter locations is currently being addressed as Operable Units 2 and 3 of the VB/I-70 Superfund site.

    For more information visit: http://www.epa.gov/superfund/vb-i70

    Raising a Dam — @ColoradoStateU

    Here’s the release from Colorado State University (Anne Manning):

    Gross Dam spillway design being put to the test by CSU civil engineers

    On any given day, the roar of water cascading over a 20-foot-high dam spillway greets visitors to Colorado State University’s Hydraulics Laboratory. Muck boots are required footwear, as water from the spray spreads across the floor, drains into an under-floor reservoir, and flows back toward an outtake pipe for recycling.

    The experimental spillway, constructed by CSU civil engineers, is a test bed for an ambitious dam-raising project in southwest Boulder County by Denver Water. CSU engineers are applying their hydraulics expertise to help verify key design and functionality aspects of the spillway, part of the public utility’s planned upgrade to Gross Dam. The reservoir impounded by Gross Dam provides water to more than 1.4 million residents along Colorado’s Front Range.

    The engineering team designing the project for Denver Water, Stantec and primary subcontractor AECOM, commissioned civil engineering professors Chris Thornton and Rob Ettema to create a 1:24 working scale model of the heightened dam’s new spillway. The spillway is the only portion of the dam over which water passes.

    A project of this magnitude requires a physical hydraulic model, Thornton said.

    “Computers have come a long way, but they’re not even close to being able to resolve what’s happening in terms of interaction of forces,” Thornton said. “Turbulence and air entrainment are very hard to model accurately.”

    Stepped spillway

    Taylor Hogan, a civil engineering master’s student and Hydraulics Laboratory manger, led the design and building of the model, which required close to 500 custom-built pieces. It is called a stepped spillway, which dissipates energy from the water as it flows over the dam. The steps slow the water, trap air bubbles, and allow water to safely descend. Adding to the model construction’s complexity is a slight arch to the spillway profile – mimicking the current profile.

    The CSU engineers are now testing and documenting performance, including capacity, flow rate, and ability to handle a major influx of water from a storm or natural disaster. When complete, Gross Dam’s will be the tallest stepped spillway in the United States.

    The planned height of the dam necessitated the stepped design. The dam is slated to be raised 131 feet over its current height of 340 feet, increasing the capacity of Gross Reservoir by about 25 billion gallons.

    “The expansion will allow Denver Water to add balance and resiliency to its water collection system, which today is at risk of damage from natural disasters such as wildfires and floods,” said Jeff Martin, Denver Water’s Gross Reservoir Expansion Project program manager. “It will also help to manage the greater uncertainty that comes with a changing climate.”

    The Stantec/AECOM team specified that the spillway be able to manage extreme high flows they estimate to be possible during the rare occurrence of a massive storm.

    “The spillway is designed very conservatively and must perform safely when exposed to extreme conditions,” Ettema said.

    Engineering students Taylor Hogan and Blake Biethman stand next to the Gross Reservoir expansion stepped spillway model, Sept. 9, 2019. Photo credit: CSU/Bill Cotton

    Remaining work

    The CSU researchers are wrapping up the modeling work for Stantec/AECOM to complete the spillway design. The remaining work includes optimizing the layout of the energy-dissipation basin at the bottom of the spillway, to ensure Gross Dam’s design meets safety requirements. Design engineering on the overall dam project is expected to extend through the end of 2020.

    Water flows through the distilling basin at the bottom of the spillway model. Photo credit: CSU/Bill Cotton
    Gross Reservoir in the mountains to the southwest of Boulder. Denver Water hopes to increase the height of the dam 131 feet, to a new height of 471 feet, to store three times as much water, which it says will help it meet increasing demands and to better weather severe droughts.