#ColoradoRiver Futures – “#Climate & the River” Edition — @AmericanRivers #COriver #aridification

The “bathtub ring” at Lake Powell evidences lower flows coming into the reservoir. According to preliminary data from the Bureau of Reclamation, the total inflow into Lake Powell for the 2020 water year was about 6 million acre-feet, just 55% of average. Photo credit: Brent Gardner-Smith/Aspen Journalism

From American Rivers (Sinjin Eberle and Page Buono):

Over the last few weeks, we’ve focused our attention on the recent study published by the Center for Colorado River Studies about the future of the Colorado River, given some alarming new data synthesized by the Center. You’ll likely recognize the authors—Kevin Wheeler, Jack Schmidt, Eric Kuhn, Brad Udall and others—who are no strangers to ongoing dialogue about the river. In our first post, we covered the broad takeaways, the potential ramifications of the study’s finding on water management in the West, and on the importance of the inconvenient science it elevates. In the second post, our “Changed River” edition, we let the line “The Colorado River has been profoundly altered from its highest reaches to its delta” percolate and came out even more committed to the preservation of the river and inspired to consider and address new challenges revealed by the study that will demand even more aggressive action on behalf of the river.

In this, our “Climate & the River” edition, we’ll highlight findings from the study that underscore how important it is that, as we look to the future, we model future hydrology not only by understanding the past, but by looking ahead to the impacts of back-to-back and longer-term droughts paired with warming temperatures that precipitate aridification. As climate scientist Brad Udall likes to say, it’s a “hot drought,” where warmer temperatures are leading to less water in the river, even if precipitation is actually remaining roughly the same.

December 4, 2015
Credit: Sinjin Eberle
UT, Lake Powell

The stakes of including, or ignoring, the likelihood of a hotter and drier future in our decision making are high. Authors open their study with this quote for a reason:

“The likelihood of conflict rises as the rate of change within the basin exceeds the institutional capacity to absorb that change.” Wolf, A. T., S. B. Yoffe and M. Giordano (2003).

If you’re eager for the takeaways, you can skip to the bottom of this post. If you’re curious about how they arrived there, and why, read on!

The assumptions we make to inform future management are critical, and when it comes to predicting future hydrologic conditions that answer the questions: “How much water will be available? In what form? And when?”, it is irresponsible not to model and plan—to the greatest extent possible—for the conditions climate science predicts.

Shot of the North Fork of the Gunnison River, Paonia, Colorado. Photo credit: Sinjin Eberle

To that end, the authors compiled diverse sets of data to represent a range of past and future conditions and applied them to the management alternatives that we highlighted in the first blog of this series. The findings of their analysis underscore discrepancies between projections that look solely to the past, those that ground themselves in recent hydrologic regimes, and those that forecast to the future based on various climate projections.

Currently, the Bureau of Reclamation utilizes two different hydrologic model sets, one called the Direct Natural Flow (DNF) and the other called Stress Test hydrology. Each model is derived from the average flows across different periods in history. The DNF model relies on estimated natural flows from 1906-2018. Authors of the study point out that this 113-year period includes what’s referred to as the “20th century pluvial period” from 1906-1929, an unusual, bountifully wet period, from a hydrologic perspective. According to Udall, the patterns represented by the DNF data are unlikely to re-occur in current management timeframes. The Stress Test hydrology skips this period and jumps to a 31-year range between 1988-2018, which includes both high flow years, and years of drought beginning in 2000 – what the authors refer to as the ongoing “millennium drought.” In addition to those, authors integrated or developed the following forward-looking data sets:

Graphic credit: American Rivers

Now, if that looks super technical, it’s because it is! These detailed and diverse data sets allowed the authors to model unique scenarios, including three different scenarios of extended drought, all of which have occurred in the past, and for decreases in runoff associated with the anticipated effects of aridification. They chose these hydrology sets to test alternative management strategies under long periods of low runoff, and the kind of runoff we might see under increasingly warmer temperatures, both of which the authors describe as “…plausible futures that should be considered in planning purposes.” The range of futures hydrology predict average flows at anywhere from 14.76 million acre feet (maf), the flows modeled under the DNF hydrology scenario, and down to 9.71 maf a year under the RCP 8.5_100 data set.

The authors integrated these hydrologic scenarios alongside multiple scenarios for consumptive use and management in an attempt to better understand possible future impacts to the Colorado River, and those who depend on it. As the study points out: there is more work to be done here, and the authors hope this inspires future studies that imagine more management scenarios. But even though they aren’t comprehensive, the overall observations the authors make after running these scenarios are prescient, and compelling.

In a nutshell, the authors state that “climate change is causing flow declines, and additional declines are likely to occur,” and point to the following as both evidence and inspiration for more creative thinking as we plan for the future:

  • Between 2000-2018, flows in the Colorado River were approximately 18% less than from 1906-1999.
  • The ongoing drought and low-flow years that we’ve seen since 2000 are, quite likely, not going away any time soon. And even they may not be accurate representations of the future because as temperatures rise and catalyze further aridification of the region, more dramatic declines in flows are likely.
  • Given the unpredictability of the future paired with the immense likelihood of less, not more water, is it incumbent upon water managers and users to plan and think proactively and creatively.
  • The DNF hydrology predicts approximately 2 maf/year more than we’ve seen the last 20 years, while the RCP 8.5_100 hydrology predicts nearly 3 maf/year less than we’ve seen in the last 20 years. As Udall says, that 5 maf range is, frankly, enormous.
  • Authors warn that these conditions paired with unrealistic aspirations for development of future flows will “result in a difficult, basin-wide reckoning.” Incremental tweaks to the management of the river may no longer work, and the study calls upon us to think now about a drier future, not to wait until we’re there. And perhaps to acknowledge that, in many ways, we already are.

    #Centennial Water joins others to address potential #drought — The #HighlandsRanch Herald

    From Centennial Water via The Highlands Ranch Herald:

    Fourteen Front Range water utilities met this month to collaborate about the locally dry conditions and the potential drought situation ahead. Centennial Water & Sanitation District — the water and wastewater provider for Highlands Ranch and Solstice — was at the table, according to a news release from the district.

    “The Drought Coordination Group reconvenes when drought conditions worsen, as determined by the U.S. Drought Monitor,” said Swithin Dick, water resources administrator for Centennial Water, according to the release. “The objective is to coordinate and offer cooperation around local water utilities sharing ideas, tools and messaging.”

    Colorado Drought Monitor February 16, 2021.

    According to the latest drought monitor (http://droughtmonitor.unl.edu/), released [February 16, 2021], Douglas County is currently experiencing exceptional drought conditions. When looking at Colorado, the entire state is experiencing some level of drought from moderate conditions to exceptional, according to the release.

    “As part of our annual planning we look at our water resources including water storage in reservoirs, groundwater supply, and estimating potential runoff from snowpack,” said Dick, according to the release.

    Centennial Water’s storage capacity is below average going into March. Over the last five years the district’s average at this time of year has been 8,489 acre feet and it is currently at 5,750 acre feet. To put that in perspective, the average demand annually by Centennial Water customers is 16,500 acre feet.

    “April is when we find out where we are at,” Dick said in the release. “Things do not look good at this point. We are beginning to plan now for a low runoff year, which puts us on a drought watch.”

    Centennial Water relies on spring precipitation and runoff to boost its water storage, but the reality is that might not come this year, according to the release.

    “Centennial Water staff are working diligently in case the dry conditions continue,” said General Manager John Kaufman, according to the release. “We are in a drought and we are taking steps now in anticipation of a dry summer. We are asking customers to start conservation planning and taking steps at home to use water more efficiently.”

    Small things that can be done at home include checking for leaks throughout the home and being patient with outdoor watering, according to the release.

    “Water budgets for outdoor irrigation begin in April; there is no reason to turn on irrigation before then,” added Kaufman, according to the release.

    Water conservation tips, information and the latest news from Centennial Water are available through the monthly Water eNewsletter. To sign up, customers can send an email to info@highlandsranch.org.

    Highlands Ranch

    Eagle County #snowpack improves, but a lot more snowfall still needed — The #Vail Daily #runoff

    Westwide SNOTEL basin-filled map February 24, 2021 via the NRCS.

    From The Vail Daily (Scott Miller):

    Long-range forecast calls for continued drought

    Here’s the good news: February was a good month for snowfall in the area. Here’s the bad news: It wasn’t enough to break us from our current drought conditions.

    A more-snowy February managed to provide a good bit of catch-up moisture to local snow measurement sites. The “snow water equivalent” at those sites is currently close to normal, as measured by 30-year median snowfall.

    But heading into March and April, the area’s snowiest months, it’s easy to fall behind.

    For instance, the Feb. 18 snow water equivalent on Vail Mountain was at 89% of normal. Even after a cool weekend with some snow, the Feb. 22 figure had dropped to 86% of normal.

    Diane Johnson, a spokesperson for the Eagle River water & Sanitation District, said at least some snow needs to fall just about every day for the snowpack to keep up with normal levels.

    The Feb. 22 “snow water equivalent” on Vail Mountain was 86% of the 30-year median. That isn’t enough to break us out of the current drought. Graphic credit: Eagle River Water & Sanitation District

    The winter of 2020-2021 is so far better than the record-low season of 2011-2012. That year, the snowpack peaked on March 4. The usual peak in the area comes April 25. A warm March and April also quickly evaporated Vail Mountain’s snowpack in 2012, which at the measurement site was gone by the first week of April.

    Little help on the horizon

    While this season is at least close to seasonal norms at the moment, there may not be much help coming in the immediate future…

    To break our current drought, snowfall and cold temperatures will need to be sustained “over a long period of time.” That isn’t in the forecast.

    The National Weather Service Climate Prediction Center’s 30-day forecast, issued Feb. 18, is calling for both above-average temperatures and below-average precipitation for Colorado…

    That long range forecast has Johnson concerned.

    “We’re preparing for drought this summer,” Johnson said, adding that the district is urging its customers to invest in efficient irrigation systems and outdoor plants that don’t require much water.

    “Of course we’re stoked for the snow, but it just doesn’t change the trajectory of this year right now,” Johnson said.

    Assistant State Climatologist Becky Bolinger is also concerned about this year’s snowpack.

    “We need above average peak snowpack to start chipping away (at the drought),” Bolinger said. Current snowpack is better than it was, she said, but it’s “unlikely” we’ll see the kind of recovery needed.

    Almost as important as the snowpack itself is the moisture content of the ground covered by that snow.

    Dry soil hurts streamflows

    In the spring, soil moisture is the first thing replenished by melting snow. Thirsty ground means less runoff for streams. That means less water flowing to reservoirs and for those who irrigate crops. The Eagle River Valley relies mostly on streamflow for domestic water supplies.

    Bolinger added that complicating the deficit in soil moisture has been a four-year stretch in which the area’s summer monsoon rains in July and August haven’t developed. Those rains help keep the ground moist and help maintain streamflows.

    Losing those monsoonal rains has also dried out plant life…

    The current pattern has been “painful,” Bolinger said. “It’s going to be a tough year in terms of irrigating, and I’m very concerned about the wildfire season. Keep your fingers crossed for the monsoon.”

    Former @ColoradoStateU adviser Tom Vilsack confirmed as U.S. Secretary of Agriculture — The #FortCollins Coloradoan

    Tom Vilsack, was confirmed as secretary of the U.S. Department of Agriculture on February 23, 2021. Photo credit: Colorado State University

    From The Fort Collins Coloradoan (Molly Bohannon):

    The U.S. Senate on Tuesday confirmed Tom Vilsack, a former Colorado State University System special adviser, as the agriculture secretary in the Biden administration.

    The Senate voted 92-7 to approve Vilsack’s nomination.

    Vilsack joined the CSU System in 2017 as a strategic adviser of food and water initiatives at CSU Spur for the Colorado State University System. He also worked as the global chair for the International Board of Counselors on Food and Water Initiatives.

    At his Feb. 2 hearing, Vilsack said he plans to prioritize pandemic recovery and climate change during his term. He also spoke of the importance of racial justice and equity and how he hopes to change the USDA…

    This will be Vilsack’s second term as the secretary of agriculture as he held the position for eight years in the Obama White House.

    #ColoradoSprings #stormwater fee increases approved — The Colorado Springs Gazette

    Southern Delivery System map via Colorado Springs Utilities

    From The Colorado Springs Gazette (Mary Shinn):

    Colorado Springs City Council on Tuesday unanimously approved three years of stormwater fee increases that take effect in July.

    Several council members acknowledged the fee increases are needed to make up for the city neglecting to maintain stormwater infrastructure and failing to require developers to meet stormwater standards for years, leading to a recently settled lawsuit that will require stormwater control projects to be built…

    Residential fees paid through utility bills are to go increase to $7 per month from $5 per month. Residential rates will then go up to $7.50 per month in 2022 and $8 per month in 2023, according to the approved fee structure.

    Commercial properties’ monthly fees will go up to $40.50 per acre per month from $30 per acre. In 2022, commercial fees will increase to $43 per acre per month and in 2023 to $45, the proposal shows. The fees are then expected to remain flat through 2035, said Richard Mulledy, Colorado Springs stormwater enterprise manager.

    The fee increases are needed to help cover $45 million in projects required by a consent decree approved in the case brought against the city by the EPA, Pueblo County and the Lower Arkansas Valley Water Conservancy District. The lawsuit stated, in part, that stormwater management in the city was underfunded.

    Stormwater fees also must cover $460 million the city is spending over 20 years to build 71 stormwater projects as part of its 2016 agreement with Pueblo County. The agreement was needed to allow Colorado Springs to start pumping water needed to fuel city growth from Pueblo Reservoir through its Southern Delivery System pipeline.

    Fountain Creek photo via the Fountain Creek Watershed Flood Control and Greenway District