Alternative Water Transfers in Colorado: A Review of Alternative Transfer Mechanisms for Front Range Municipalities

Environmental Defense Fund (EDF) | November 1st, 2016

Alternative water transfers (ATMs) refer to various methods, activities, and frameworks that have been established to transfer water on a temporary or intermittent basis

Alternative water transfers (ATMs) refer to various methods, activities, and frameworks that have been established to transfer water on a temporary or intermittent basis, primarily from agriculture to other uses. They are labeled as “alternative” because they represent a type of water transfer that does not result in the permanent dry-up of agricultural land, which has been the primary form of water transfers in much of Colorado for decades. ATMs are a body of activities that represent general frameworks or concepts to be molded to the specific conditions of a place and need. The Environmental Defense Fund (EDF) obtained a grant opportunity to fund research, analysis, and outreach toward the development of ATMs with the potential to improve the financial returns and long-term viability of farming, maintain or improve streamflows which support environmental and recreational activities, and provide a cost-effective means for municipalities to maintain water supply reliability into the future. The purpose of this project is to develop a comprehensive financial comparison of the water supply development options currently pursued by municipalities to applicable ATMs and to develop recommendations that can increase the application of specific ATM structures with the potential joint benefits to municipal and agricultural water users.

Alternatives Report Post-2026 Operational Guidelines and Strategies for Lake Powell and Lake Mead

U.S. Bureau of Reclamation (USBR) | January 17th, 2025

In December 2007 the Secretary of the Interior adopted coordinated operating guidelines for operation of Glen Canyon Dam and Hoover Dam for an interim period that expires

In December 2007 the Secretary of the Interior adopted coordinated operating guidelines for operation of Glen Canyon Dam and Hoover Dam for an interim period that expires in 2026. To address long-term Colorado River operations after the expiration of these guidelines, the United States Department of the Interior initiated a National Environmental Policy Act process on June 16, 2023, to develop and adopt successor domestic guidelines and agreements for the operation of Glen Canyon Dam and Hoover Dam to take effect in mid-2026, before the current operational framework expires. On November 20, 2024, the Bureau of Reclamation published the range of alternatives planned for analysis in the draft environmental impact statement and committed to providing additional information in a subsequent report. This report describes these alternatives and the process for developing them in more detail. The alternatives were developed over the past year and incorporate considerable input received from the Colorado River Basin States, Colorado River Basin Tribes, conservation organizations, other federal agencies, and other stakeholders during that time. Throughout 2024, the Bureau of Reclamation worked extensively with these key partners to integrate their input into the range of alternatives. The alternatives identified in this report provide a reasonable and broad range of Colorado River operations that capture an appropriate range of potential environmental impacts from implementing new operational guidelines post-2026. Click here for USBR notes on the alternatives development process.

Amplification of downstream flood stage due to damming of fine-grained rivers

Nature Portfolio (Springer Nature) | June 1st, 2022

River dams provide many benefits, including flood control. However, due to constantly evolving channel morphology, downstream conveyance of floodwaters following dam clo

River dams provide many benefits, including flood control. However, due to constantly evolving channel morphology, downstream conveyance of floodwaters following dam closure is difficult to predict. Here, we test the hypothesis that the incised, enlarged channel downstream of dams provides enhanced water conveyance, using a case study from the lower Yellow River, China. We find that, although flood stage is lowered for small floods, counterintuitively, flood stage downstream of a dam can be amplified for moderate and large floods. This arises because bed incision is accompanied by sediment coarsening, which facilitates development of large dunes that increase flow resistance and reduce velocity relative to pre-dam conditions. Our findings indicate the underlying mechanism for such flood amplification may occur in >80% of fine-grained rivers, and suggest the need to reconsider flood control strategies in such rivers worldwide.

An Assessment of Potential Severe Droughts in the Colorado River Basin

American Water Resources Association (AWRA) | September 15th, 2022

An extremeness threshold determines the regional response of floods to changes in rainfall extremes

Nature Portfolio (Springer Nature) | August 26th, 2021

Precipitation extremes will increase in a warming climate, but the response of flood magnitudes to heavier precipitation events is less clear. Historically, there is lit

Precipitation extremes will increase in a warming climate, but the response of flood magnitudes to heavier precipitation events is less clear. Historically, there is little evidence for systematic increases in flood magnitude despite observed increases in precipitation extremes. Here we investigate how flood magnitudes change in response to warming, using a large initial-condition ensemble of simulations with a single climate model, coupled to a hydrological model. The model chain was applied to historical (1961–2000) and warmer future (2060–2099) climate conditions for 78 watersheds in hydrological Bavaria, a region comprising the headwater catchments of the Inn, Danube and Main River, thus representing an area of expressed hydrological heterogeneity. For the majority of the catchments, we identify a ‘return interval threshold’ in the relationship between precipitation and flood increases: at return intervals above this threshold, further increases in extreme precipitation frequency and magnitude clearly yield increased flood magnitudes; below the threshold, flood magnitude is modulated by land surface processes. We suggest that this threshold behaviour can reconcile climatological and hydrological perspectives on changing flood risk in a warming climate.

Annual Operating Plan for Colorado River Reservoirs 2021

U.S. Bureau of Reclamation (USBR) | December 9th, 2020

Annual Report on the Colorado River Basin Salinity Control Program 2020

Colorado River Basin Salinity Control Advisory Council (CRBSCAC) | December 31st, 2020

Anthropogenic warming has ushered in an era of temperature-dominated droughts in the western United States

American Association for the Advancement of Science (AAAS) | November 6th, 2024

Anthropogenic warming impacts on California snowpack during drought

American Geophysical Union (AGU) | March 15th, 2017

Sierra Nevada climate and snowpack is simulated during the period of extreme drought from 2011 to 2015 and compared to an identical simulation except for the removal of t

Sierra Nevada climate and snowpack is simulated during the period of extreme drought from 2011 to 2015 and compared to an identical simulation except for the removal of the twentieth century anthropogenic warming. Anthropogenic warming reduced average snowpack levels by 25%, with middle‐to‐low elevations experiencing reductions between 26 and 43%. In terms of event frequency, return periods associated with anomalies in 4 year 1 April snow water equivalent are estimated to have doubled, and possibly quadrupled, due to past warming. We also estimate effects of future anthropogenic warmth on snowpack during a drought similar to that of 2011–2015. Further snowpack declines of 60–85% are expected, depending on emissions scenario. The return periods associated with future snowpack levels are estimated to range from millennia to much longer. Therefore, past human emissions of greenhouse gases are already negatively impacting statewide water resources during drought, and much more severe impacts are likely to be inevitable.

Anticipating drought-related food security changes

Nature Portfolio (Springer Nature) | September 29th, 2022

Food insecurity early warning can provide time to mitigate unfolding crises; however, drought remains a large source of uncertainty. The challenge is to filter unclear or

Food insecurity early warning can provide time to mitigate unfolding crises; however, drought remains a large source of uncertainty. The challenge is to filter unclear or conflicting signals from various climatic and socio-economic variables and link them to food security outcomes. Integrating lag-1 autocorrelation diagnostics into remotely sensed observations from the Soil Moisture Active Passive (SMAP) mission and food prices, we found dramatic improvement in anticipating the timing and intensity of food crises, except in conflict settings. We analysed drought-induced food crises globally in the SMAP record (since 2015; approximately five per year). The change in soil moisture autocorrelation, which we term the Soil Moisture Auto-Regressive Threshold (SMART), signalled an accurate food security transition for all cases studied here (P