White paper: The Future Hydrology of the #ColoradoRiver Basin — Center for Colorado River Basin Studies #COriver #aridification

Read the two-page brief
Read the complete paper

From email from the Center for Colorado River Basin studies:

Long-range planning of the water supply provided by the Colorado River requires realistic assessments of the impact of a continuation of the current drought that began in 2000, the impact of potentially extreme future droughts, and the long-term and progressive decline in watershed runoff that is caused by a warming climate.

In this white paper, we’ve developed methods to make quantitative estimates of likely future conditions, thereby providing an approximate answer to the question, “How dry might future conditions in the Colorado River watershed become?” Our analysis is guided by the principle that what has happened in the past might happen again in the future. When viewed from the perspective of past flows reconstructed from tree-rings, or future flows projected from climate models, significantly more severe droughts are not only plausible, but increasingly likely, recognizing that hotter and drier conditions are making matters worse.

We identified the magnitude and duration of the most severe droughts of the past 600 years. Three past droughts stand out in the record of prior flows. We use the term millennium drought to refer to the period between 2000 and 2018—mean flow of 12.44 million acre feet/year (maf/yr) for 19 years; 2.3 maf/yr less than the long term mean of 14.76 maf/yr computed from the 1906-2018 natural flow record. The mid-20th century drought was the period between 1953 and 1977—mean flow of 12.89 maf/yr for 25 years; 1.9 maf/yr less than the long term mean. Both of these are plausible scenarios of future droughts, because they have occurred in the recent past and indeed may be continuing today. We use the term paleo tree-ring drought to refer to the period between 1576 and 1600 that is based on tree ring estimates of streamflow—mean flow of 11.76 maf/yr for 25 years; 3 maf/yr less than the long term mean.

Our results demonstrate that planning in which the 1988-2018 period containing the current drought is used as a stress test might not consider drought scenarios that are sufficiently extreme. The future might be far drier than managers currently anticipate.

An additional aspect of our research is that we developed and implemented a scheme for incorporation of our estimates of future drought at Lees Ferry into the Colorado River Simulation System (CRSS).

In the paper:

  • Details of three drought scenarios that would severely test the operational rules, and planning and management strategies of the Colorado River system.
  • An example of the stresses that a severe sustained drought would place on the Colorado River possibly lowering pool elevations of Lake Powell to levels less than needed to produce hydropower.
    An examination of whether the declining streamflow trend in the 20th century is due to the anomalous wet period from 1906-1929.
  • Separate sidebar analyses on historical flow in the Colorado River, natural flow losses below Hoover Dam, the estimation of streamflow in the absence of human influence, details of the unusual Early 20th century pluvial period from 1906-1929, and the effects of climate related forest change on runoff.
  • The latest briefing from Western Water Assessment is hot off the presses

    The year-to-date global land and ocean surface temperature was also the second highest in the 141-year record at 1.85°F (1.03°C) above the 20th-century average of 57.3°F (14.0°C). This value is only 0.09°F (0.05°C) less than the record set in 2016. Credit: NOAA

    Click here to go to the Western Water Assessment Intermountain West Climate Dashboard (scroll down for the latest briefing):

    Latest Briefing – September 15, 2020 (UT, WY, CO)

  • Record hot temperatures and near-record to record low precipitation during August led to a major degradation of drought conditions. D3 drought expanded to cover nearly 80% of Utah, 50% of Colorado and 20% of Wyoming. D4 drought emerged in central Utah and eastern Colorado. Two large wildfires burned in Colorado during August and are now the 1st and 5th largest wildfires in state history. La Niña conditions currently exist in the eastern Pacific Ocean and there is a 75% chance of La Niña conditions continuing through the fall and winter.
  • Throughout most of Colorado, Utah and Wyoming, August precipitation was less than 50% of normal Western US Seasonal Precipitation. Nearly all of Utah and half of Wyoming received less than 25% of normal precipitation. A significant portion of Utah received less than 5% of normal precipitation. The northern Front Range of Colorado, and north-central Wyoming received 50 – 90% of normal precipitation and four locations throughout the region received above-average precipitation from isolated storms.
  • Temperatures were above normal for the entire region during August Western US Seasonal Precipitation. Regionally, Utah experienced the warmest conditions with temperatures 4 – 6 degrees above normal for much of the state and portions of eastern and central Utah saw temperatures that were 6 – 8 degrees above normal. Temperatures were generally 2 – 4 degrees above normal in Colorado and Wyoming. Temperatures were 4 – 6 degrees above normal in western Colorado and along the Front Range. The hottest August temperatures on record were observed in nearly half of the Intermountain West, including Denver, Grand Junction and Salt Lake City Western US Seasonal Precipitation.
  • Streamflow in nearly all river basins in Colorado and Utah were below normal during August Western US Seasonal Precipitation. August streamflow for much of Wyoming was near-normal (25 – 75th percentile), but basins in southern and western Wyoming were below normal (< 25th percentile). Despite low regional runoff volumes in 2020 and persistent drought, reservoir storage remains relatively high. Statewide, reservoirs in Utah are at 67% capacity and 109% of average levels and reservoirs in Colorado are 51% full and 83% of average storage levels. In Wyoming, current reservoir storage levels are general above average. Storage on large reservoirs in the Colorado River basin is variable with Flaming Gorge Reservoir relatively full (86% capacity, 100% of average), Navajo Reservoir slightly below normal (71% capacity, 86% of average) and Lake Powell half-empty (48% capacity, 63% of average).
  • West Drought Monitor September 8, 2020.
  • A record hot August and extremely low precipitation caused a significant worsening of drought conditions throughout the region during August. D3 drought expanded across the entire region, especially in Utah (D3 covers 80% of state) and Colorado (D3 covers 50% of state) Western US Seasonal Precipitation. In Wyoming, D3 drought expanded to cover 21% of the state; western Wyoming is the only portion of the region not experiencing drought conditions. D4, the worst category of drought, emerged in central Utah and eastern Colorado. There was a one category improvement in drought conditions in central and southeastern Colorado; these two areas are now in D1 drought.
  • A La Niña Advisory was issued by the NOAA Climate Prediction Center on September 10th. La Niña conditions currently exist and there is a 75% probability of La Niña conditions continuing through fall and winter. As of early September, sea surface temperatures and atmospheric variables indicate La Niña conditions and the majority of Pacific Ocean temperature forecasts project a continuation of La Niña conditions through fall and early winter Western US Seasonal Precipitation. The official CPC/IRI ENSO forecast is calling for a 75% chance of La Niña conditions during fall and winter. By spring, there is an increasing probability of neutral ENSO conditions Western US Seasonal Precipitation. On a shorter timescale, the NOAA monthly climate outlooks show an increased probability for above average temperatures and below average precipitation for most of the region. The NOAA seasonal climate outlook (3 month timescale) indicates a higher probability for above average temperatures for the entire region and below average precipitation for Colorado and Utah.
  • Significant August weather event. Record heat, low precipitation, worsening drought and large wildfires were all significant events on a regional scale during August. August was the hottest on record for the entire southwestern United States, including Colorado, Utah, Arizona, California, Nevada and New Mexico Western US Seasonal Precipitation. August 2020 was the driest on record for Utah and the fifth driest on record for Colorado and Wyoming. Hot and dry conditions during August caused rapid degradation of drought conditions and extreme drought (D3) now covers approximately half of the three state region. Several significant wildfires began burning in Colorado during August. The Pine Gulch fire, north of Grand Junction, CO, is 95% contained (9/10/20) but burned 139,000 acres and is the largest wildfire in state history. The Cameron Peak fire has burned 102,000 acres as of 9/10/20 and is currently the fifth largest fire in state history. Up to 14” of snow fell on the fire on 9/8/20, but the fire is only 4% contained (9/10/20) and still remains a threat as warm conditions return to the region.
  • A Colorado dashboard seeks to put a price on future wildfires, other natural disasters amid a warming climate — The #Colorado Sun

    The Cameron Peak fire soon after it started on Aug. 13, 2020. By Sept. 11, the fire had grown to more than 102,000 acres and was not expected to be considered out until Oct. 31. Photo credit: InciWeb via The Colorado Sun

    From The Colorado Sun (Lucy Haggard):

    FACE:Hazards offers a look into how much Colorado might have to fork out to respond to future natural hazards, and how communities could work now to avoid going broke later

    As Colorado experiences a record-breaking wildfire season amid accelerating population growth and statewide drought, many are asking: How can we be resilient in the face of inevitable disaster?

    It’s a dense question. To find an answer, the Colorado Water Conservation Board teamed up with the Division of Homeland Security and Emergency Management and a handful of other state agencies to create the Future Avoidance Cost Explorer. The Federal Emergency Management Agency joined the effort as part of its Hazard Mitigation Grant Program, and contracting company Lynker helped with data analysis as well as creating an interactive website. Just a year after the project started, the technical report and the website were published this spring.

    Also known as FACE:Hazards, the dashboard explores the economic cost of natural hazards under a variety of different potential scenarios as they might look in 2050. Users can explore varying degrees of climate change and population growth, dive into the economics of one specific economic sector like agriculture or recreation, differences between geographic regions, and peruse the impacts different programs have on disaster resilience.

    A screenshot from the FACE:Hazards dashboard. This particular model analyzes the economic impact of wildfire based on a moderately warmer climate and medium population growth. Via The Colorado Sun

    The price tags estimated for these scenarios are likely lower than they would be in real life, according to Megan Holcomb, senior climate specialist at the Colorado Water Conservation Board and technical lead for the project. This is in large part due to incomplete data; not every county collects the same degree of data on the same economic sectors, for example, so the project could only do analysis when data from every county lined up. Additionally, the data is at a county-level scale, so while it gives a good picture of the state as a whole, cities and towns will need their own assessments for better accuracy.

    “We don’t know what parts of economies will be impacted the hardest sometimes,” Holcomb said. “We don’t know where in the state the most serious wildfires are going to happen, we don’t know how that’s going to affect recreation or tourism afterwards. A lot of disasters, by their very nature, are unpredictable … but we just know that these disasters will happen more frequently, and back to back or in conjunction with others.”

    Despite its shortcomings, Holcomb says the dashboard and its accompanying technical report can start to fill a much-needed role for decision-makers.

    “The Catch-22 of planning far into the future is that’s not how the decision-making process works, and not how funding works,” Holcomb said. “It’s very challenging, but we have to start somewhere.”

    While the project could have just been presented as a technical report to legislators, Steve Boand, state hazard mitigation officer and a project adviser, said the team decided from the get-go to make the data more accessible. Not only does this benefit lawmakers who likely don’t have the time to parse pages and pages of data, it also helps communicate the issue in a way that starts a conversation with the agencies like the Office of Emergency Management.

    “The goal is for local communities to ask, ‘What do you mean, this is going to cost $300 milion a year, how does that work?’” Boand said. “The general economic impact from fire, drought and flood can be staggering.”

    Of the $997,000 dedicated to the project, 75% came from FEMA, with the remainder funded through the state. Ryan Pietramali, recovery division director for FEMA Region 8, which includes Colorado, noted that this is the nation’s first project to take such a thorough look at the practical impacts of disaster planning.

    @USBR launches prize competition to improve streamflow forecasting

    Streamflow Forecasting Prize Competition.

    Here’s the release from the Bureau of Reclamation (Peter Soeth):

    The Bureau of Reclamation is launching a prize competition to improve short-term streamflow forecasts. Evolving data science such as artificial intelligence, machine learning and high-performance computing are starting to be used in streamflow forecasting. The Streamflow Forecast Rodeo competition seeks to spur innovation using these technologies.

    Reclamation is making up to $500,000 available through this prize competition.

    “Streamflow forecasts are integral to managing water,” said Reclamation Commissioner Brenda Burman. “Finding improvements to forecasting will allow water managers to better operate their facilities for high flows, mitigate drought impacts and maximize hydropower generation.”

    This competition delivers on the Department of the Interior and Reclamation’s commitment to improve water availability. It also supports the goals of the President’s memo on Promoting the Reliable Supply and Delivery of Water in the West.

    The competition will begin with a “pre-season” in August, followed by a year of real-time forecasting beginning October 1, 2020. The pre-season will allow competitors to build and refine their forecast methods. The real-time forecasting competition will have solvers forecast streamflow for the next 10 days, updated daily at multiple locations across the West, for the duration of the competition.

    Reclamation is partnering with the CEATI International’s Hydropower Operations and Planning Interest Group, NASA Tournament Lab and Topcoder on this crowdsourcing competition. Partnering with CEATI HOPIG includes a companion project that will provide benchmarks against which the competitors will be evaluated, as well as scoring of solver forecasts by RTI International. Other CEATI HOPIG members making contributions include Department of Energy’s Water Power Technologies Office, Tennessee Valley Authority, Hydro-Quebec, and Southern Company. To learn more about this competition, please visit https://www.usbr.gov/research/challenges/streamflowrodeo.html.

    Reclamation conducts prize competitions to spur innovation by engaging a non-traditional, problem-solver community. Through prize competitions, Reclamation complements traditional design research to target the most persistent science and technology challenges. It has awarded more than $1,000,000 in prizes through 22 competitions in the past 6 years. Please visit Reclamation’s Water Prize Competition Center to learn more.

    @USBR invests $3.3 million for internal applied science projects to improve modeling, forecasting and data tools

    Photo shows the sediment laden Muddy Creek at its confluence with Anthracite Creek located 16 miles northeast of Paonia, Colorado. The two creeks form the North Fork of the Gunnison River. Understanding and estimating sedimentation in rivers and reservoirs is one of the applied science tools that Reclamation will fund with this announcement. Photo credit: USBR

    Here’s the release from the Bureau of Reclamation (Peter Soeth):

    The Bureau of Reclamation Commissioner Brenda Burman announced that Reclamation will invest $3.3 million in 21 projects for WaterSMART Internal Applied Science Tools that build technical capacity within Reclamation.

    “Information gained from these applied science tools will allow Reclamation and our partners to use best-available science for optimal water management under variable hydrologic conditions,” Commissioner Burman said. “The projects announced today will help inform specific water management decisions throughout the West.”


    A project will assist New Mexico and reservoirs throughout the West. It will receive $199,764 to implement a known model to simulate regional climate and physical processes to estimate daily, monthly and annual evaporation across Elephant Butte Reservoir. These estimates will be compared to alternative estimates. The results will be used by the Albuquerque Area Office to support operations, to facilitate method comparison and identify future planning, operational and research needs on the topic. It will help with the development of alternative evaporation estimation techniques, production of daily evaporation time series at a reservoir and a broadening of weather prediction modeling capabilities.

    Another project in Arizona will receive $200,000 to enhance precipitation and soil monitoring information in the Aravaipa watershed northeast of Tucson. Currently, there are only two weather stations within the watershed. The project includes the installation of two stations to monitor precipitation and soil moisture, which will better inform the Natural Resources Conservation Service forecasting models and United States Geological Survey surface water models. The work proposed in this project will help Reclamation and local partners predict flood risk, drought, erosion, and water quality concerns and better plan mitigation of these water management issues.

    A third project will receive $120,000 to do predictive modeling to generate maps of invasive quagga and zebra mussel risk. The results will allow Reclamation to dedicate limited resources to high-risk locations and prepare facilities for potential control costs.

    To view a complete list of projects, please visit http://www.usbr.gov/watersmart/appliedscience.

    Applied Science Tools are part of the WaterSMART Program. Through WaterSMART, Reclamation works cooperatively with states, tribes and local entities as they plan for and implement actions to increase water supply reliability through investments to modernize existing infrastructure and attention to local water conflicts. Visit http://www.usbr.gov/watersmart to learn more.

    @USBR released its #ColoradoRiver Simulation System modeling results [September 15, 2020] #COriver #aridification

    Colorado River “Beginnings”. Photo: Brent Gardner-Smith/Aspen Journalism

    Click here to go to the Bureau of Reclamation website for all the details:

    Over the next 5 years, the models indicate continued drought and an increased chance of potential water shortages by 2025

    Projections of future conditions of the Colorado River system are updated at least twice annually in January and August. The modeling approach and assumptions are included below along with the results of the most recent projection.

    The most recent projection of future Colorado River system conditions was produced in August of 2020.

    Navajo Dam operations update: 1,000 CFS in #SanJuanRiver critical habitat area September 16, 2020 #ColoradoRiver #COriver #aridification

    Swim class on the San Juan River. Photo: Brent Gardner-Smith/Aspen Journalism

    From email from Reclamation (Susan Novak Behery):

    In response to a cool forecast and increasing tributary flows, the Bureau of Reclamation has scheduled a decrease in the release from Navajo Dam from 800 cubic feet per second (cfs) to 700 cfs on Wednesday, September 16th, starting at 4:00 AM. Releases are made for the authorized purposes of the Navajo Unit, and to attempt to maintain a target base flow through the endangered fish critical habitat reach of the San Juan River (Farmington to Lake Powell).

    The San Juan River Basin Recovery Implementation Program recommends a target base flow of between 500 cfs and 1,000 cfs through the critical habitat area. The target base flow is calculated as the weekly average of gaged flows throughout the critical habitat area from Farmington to Lake Powell.