Quantification Settlement Agreement and Related Agreements and Documents to which Southern California Agencies are Signatories

California Natural Resources Agency (CNRA) | October 10th, 2003

Quantifying Aspect-Dependent Snowpack Response to High-Elevation Wildfire in the Southern Rocky Mountains

American Geophysical Union (AGU) | September 17th, 2024

Recent decreases in snow water storage in western North America

Nature Portfolio (Springer Nature) | May 22nd, 2023

Mountain snowpacks act as natural water towers, storing winter precipitation until summer months when downstream water demand is greatest. We introduce a Snow Storage Ind

Mountain snowpacks act as natural water towers, storing winter precipitation until summer months when downstream water demand is greatest. We introduce a Snow Storage Index (SSI), representing the temporal phase difference between daily precipitation and surface water inputs—sum of rainfall and snowmelt into terrestrial systems—weighted by relative magnitudes. Different from snow water equivalent or snow fraction, the SSI represents the degree to which the snowpack delays the timing and magnitude of surface water inputs relative to precipitation, a fundamental component of how snow water storage influences the hydrologic cycle. In western North America, annual SSI has decreased (p 

Report on Colorado River Evaporation Loss

Metropolitan Water District of Southern California (MWD) | December 12th, 2022

Report on Salton Sea Projects

California Natural Resources Agency (CNRA) | April 8th, 2016

Formed in 1905 when Colorado River flood waters breached an irrigation diversion structure and caused the river to temporarily flow into the then-dry Salton Sink, today�

Formed in 1905 when Colorado River flood waters breached an irrigation diversion structure and caused the river to temporarily flow into the then-dry Salton Sink, today’s Salton Sea is only the latest in a long succession of waterbodies to occupy the area. At 350 square miles, California’s largest lake is hydrologically connected to the Colorado River system and has been largely maintained since the 1905 event by irrigation water from agricultural production in the Imperial Valley. The historic Quantification Settlement Agreement (2003) provided California the means to implement water transfers and supply programs that allowed the state to live within its 4.4 million acre-foot basic annual apportionment of Colorado River water. Though long plagued by problems associated with its terminality—and resultant accumulation of salts, nutrients, and other impurities—the water transfers contained in the QSA meant a hastening of its ecological decline. Mitigation waters were provided for the Sea in the agreement, but are set to expire in 2017.  In response to growing concern about the impending and current deterioration of conditions at the Salton Sea, California Governor Edmund G. Brown Jr. in May 2015 created the Salton Sea Task Force to rapidly evaluate and take action to bring certainty to the Sea’s future and develop a series of findings that would guide further action at the lake. To coordinate and facilitate the actions the Governor also created the position of Assistant Secretary for Salton Sea Policy within the California Natural Resources Agency (CNRA).  The Salton Sea Task Force issued their findings in November 2015, which called for the development of a Salton Sea Management Program that covered three major elements: sustainable habitat; air quality and potential private sector energy development. The Task Force also acknowledged that a successful program depends on the following three principles: 1) strong state, federal, and local partnerships; 2) clear and achievable milestones with state directed plans to achieve them; and 3) committed participation from all stakeholders who share the goals of protecting air quality, reducing habitat impacts, and maintaining a secure Colorado River Water Supply. Task Force findings also contained a series of actions for implementation by the California Natural Resources Agency (CNRA) that included the development of a Salton Sea Management Plan with short and midterm goals for habitat and dust suppression projects, an improved public awareness and local partnerships program and an accelerated implementation of planning, permitting and construction. 

Rethinking Management of the Colorado River through Lake Powell, Grand Canyon, and Lake Mead

Utah State University | November 15th, 2024

Review of the Colorado River Interim Guidelines for Lower Basin Shortages and Coordinated Operations for Lake Powell and Lake Mead

U.S. Bureau of Reclamation (USBR) | December 18th, 2020

Spurred by an ongoing multi-year drought, decreasing system storage, and growing demands for Colorado River Water, in December 2007, Secretary of the Interior (Se

Spurred by an ongoing multi-year drought, decreasing system storage, and growing demands for Colorado River Water, in December 2007, Secretary of the Interior (Secretary) Kempthorne approved the Record of Decision (ROD) for the Colorado River Interim Guidelines for Lower Basin Shortages and the Coordinated Operations for Lake Powell and Lake Mead (Guidelines) (U.S. Department of the Interior [Department], 2007). The Guidelines, which are anticipated to be in place for an interim period through 2026, provide operating criteria for Lake Powell and Lake Mead including provisions designed to provide a greater degree of certainty to water users about timing and volumes of potential water delivery reductions, and additional operating flexibility to conserve and store water in the system. The interim nature of the Guidelines provided the opportunity to gain valuable experience for the management of Lake Powell and Lake Mead under modified operations and improve the basis for making future operational decisions, whether during the interim period or after. The requirement to document this experience is set forth in Section XI.G.7.D. of the ROD: “Beginning no later than December 31, 2020, the Secretary shall initiate a formal review for purposes of evaluating the effectiveness of these Guidelines. The Secretary shall consult with the Basin States in initiating this review” (7.D. Review). In December 2019, Secretary Bernhardt directed the Bureau of Reclamation (Reclamation) to begin a review of the Guidelines in early 2020. This Report is the culmination of that process. This Report documents Reclamation’s operational experience and provides a retrospective evaluation of whether operations and actions specified by the Guidelines have adhered to common themes and been effective with respect to the purpose stated in the ROD. The results of this evaluation are not intended to imply correctness of any particular operational provision or recommend future policies or actions. Reclamation anticipates that this Report will be a valuable source of information during upcoming activities in support of post-2026 operations – but expects this Report to be only one of many sources of information that will be available to guide that process and inform upcoming decisions on operations. Reclamation recognizes there are other areas of interest beyond the scope of this Report that should be considered in future discussions. These topics include but are not limited to the impacts to environmental, recreational, hydropower, and water quality resources, how to meaningfully engage perspectives from a diverse group of partners and stakeholders, and other recommendations from tribes, states and other stakeholders. Reclamation anticipates that additional studies and activities will be undertaken and used to inform discussions related to future operations of Lake Powell and Lake Mead. Click here for Final Report, Appendix A – Operational Documentation for Lake Powell and Lake Mead Operations Under the Colorado River 2007 Interim Guidelines Years 2008 to 2019

Royce Tipton and the Hydrology of the 1944 Treaty with Mexico

John Fleck | May 26th, 2025

Salinity Trends in a Groundwater System Supplemented by 50 Years of Imported Colorado River Water

American Chemical Society (ACS) | September 21st, 2023

The Indio subbasin of the Coachella Valley is a desert area of southern California where a growing population depends primarily on groundwater for drinking and agricultur

The Indio subbasin of the Coachella Valley is a desert area of southern California where a growing population depends primarily on groundwater for drinking and agricultural uses. The aquifer system has been supplemented with Colorado River water through managed recharge and widespread irrigation since the mid-20th century. We use a combination of geochemical modeling and trend analysis to identify changes in total dissolved solids through time, elucidate the sources of dissolved solids, and quantify the extent of contributions from those sources throughout the Indio subbasin. We conclude that recharged Colorado River water is the primary source and driver of increasing salinity, particularly in areas immediately downgradient from the recharge locations and in the eastern part of the subbasin away from the recharge ponds due to irrigation using imported water. Other contributions of dissolved solids to groundwater resources include geothermal waters, wastewater effluent, and agricultural return flow, although their effects are more localized. This study presents a broadly applicable framework for identifying sources of dissolved solids in groundwater wells and salinity trends at a regional scale in a large data set.

Salton Sea Fisheries Long-term Monitoring Sampling Report: Summer 2017

California Natural Resources Agency (CNRA) | July 13th, 2017

In early 2016, historic indices of tilapia abundance at the Salton Sea appeared to have reversed: tilapia fry were no longer observed in places where fish were regularly

In early 2016, historic indices of tilapia abundance at the Salton Sea appeared to have reversed: tilapia fry were no longer observed in places where fish were regularly visible in the past, piscivorous bird numbers at the lake were severely reduced, anglers were only catching a small fraction of past numbers of fish, and only a few small fish kills were observed. As observations of these conditions continued in early 2017, the question of whether the tilapia population was still viable was the impetus for the California Department of Fish and Wildlife (CDFW) to re-initiate gillnetting efforts.