Irregular Focal Mechanisms Observed at Salton Sea Geothermal Field: Possible Influences of Anthropogenic Stress Perturbations

Stanford University | February 12th, 2018

At the Salton Sea Geothermal Field (SSGF), strain accumulation is released through seismic slip and aseismic deformation. Earthquake activity at the SSGF often oc

At the Salton Sea Geothermal Field (SSGF), strain accumulation is released through seismic slip and aseismic deformation. Earthquake activity at the SSGF often occurs in swarm-like clusters, some with clear migration patterns. We have identified an earthquake sequence composed entirely of focal mechanisms representing an ambiguous style of faulting, where strikes are similar but deformation occurs due to steeply-dipping normal faults with varied stress states. In order to more accurately determine the style of faulting for these events, we revisit the original waveforms and refine estimates of P and S wave arrival times and displacement amplitudes. We calculate the acceptable focal plane solutions using P-wave polarities and S/P amplitude ratios, and determine the preferred fault plane. Without constraints on local variations in stress, found by inverting the full earthquake catalog, it is difficult to explain the occurrence of such events using standard fault-mechanics and friction. Comparing these variations with the expected poroelastic effects from local production and injection of geothermal fluids suggests that anthropogenic activity could affect the style of faulting.

Late Holocene Lacustrine Chronology and Archaeology of Ancient Lake Cahuilla, California

Quaternary Research (Elsevier) | May 1st, 1983

Freshwater lakes existed intermittently in the Salton Trough of southern California during the late Holocene. The lakes formed north of the subaerial Colorado River Delta

Freshwater lakes existed intermittently in the Salton Trough of southern California during the late Holocene. The lakes formed north of the subaerial Colorado River Delta whenever the Colorado River flowed west into the trough instead of south to the Gulf of California. Water filled the trough to a maximum altitude of 12 m. Stratigraphy, radiocarbon dates, and supplementary evidence document four lacustral intervals of Lake Cahuilla between A.D. 700 and 1580. Archaeological sites are associated with the 12-m shoreline and their occupation correlates with these lacustral intervals.

Letter to Governor Brown and the Legislature on the Salton Sea

Little Hoover Commission | June 24th, 2016

The Little Hoover Commission in a letter sent Friday to Governor Brown and the Legislature again renewed its call for urgent action at the Salton Sea to prevent a massive

The Little Hoover Commission in a letter sent Friday to Governor Brown and the Legislature again renewed its call for urgent action at the Salton Sea to prevent a massive public health, environmental and economic disaster in Southern California. Policymakers must replicate the effective approach taken to meet the state’s rewewable energy goals, wrote the Commission in its letter. Then, the Govenor gave a senior official the authority to do what it took to get projects through red tape at all levels of government. The model was remarkably simple: Get everyone together and get it done. The letter results from continuing oversight to which the Commission pledged in its 2015 report, Averting Disaster: Action Now for the Salton Sea. The Commission held an April 2016 hearing to get an update on the state’s progress in strategically managing the Salton Sea. It heard from the assistant secretary for Salton Sea policy at the Natural Resources Agency, as well as stakeholders from local government and the environmental community. The Commission’s letter acknowledges that momentum is building and that the state has made important progress in managing the sea, particularly with $80 million in funding in the Governor’s proposed 2016-17 budget. However, the Commission’s letter maintains that the state is not moving fast enough or allocating sufficient resources to prevent a disaster. Timelines have been delayed, short-term goals scarcely cover a fraction of exposed lakebed and much more than $80 million is needed to manage the sea.

Near-term Colorado River Operations Revised Draft Supplemental Environmental Impact Statement

U.S. Bureau of Reclamation (USBR) | October 26th, 2023

Reclamation is proposing to revise the 2007 Interim Guidelines for the operation of Glen Canyon and Hoover Dams beginning in the 2024 operating year to address the potent

Reclamation is proposing to revise the 2007 Interim Guidelines for the operation of Glen Canyon and Hoover Dams beginning in the 2024 operating year to address the potential for continued low-runoff conditions in the Colorado River Basin. The potential impacts of low runoff conditions in the remainder of the interim period (prior to January 1, 2027) pose unacceptable risks to routine operations of Glen Canyon and Hoover Dams; therefore, modified operating guidelines should be expeditiously developed. Due to size, this file has been divided. Part one, Part two.

Overview of Management and Restoration Activities in the Salton Sea

Congressional Research Service (CRS) | November 24th, 2013

Efforts to restore the Salton Sea ecosystem have been discussed and initiated through state and federal actions. Several studies by state and federal agencies have provid

Efforts to restore the Salton Sea ecosystem have been discussed and initiated through state and federal actions. Several studies by state and federal agencies have provided baseline data about the Sea, and some restoration plans have been proposed. The State of California, the Salton Sea Authority, and the federal government through the Bureau of Reclamation have devised plans for restoring the Sea. However, none of these plans are being fully implemented. Federal authorities that address restoration of the Salton Sea are generally based on creating and evaluating proposals for restoration, rather than implementing restoration activities in a comprehensive manner similar to other initiatives in the Everglades and Great Lakes. California is pursuing restoration options, but funding for implementing them is lacking. Whether or not to restore the Salton Sea remains controversial. Proponents of restoration contend that the Salton Sea ecosystem is valuable from an ecological standpoint because it is one of the few remaining large-scale wetland habitats in California for migratory birds and fish. Further, some argue that keeping the Salton Sea intact will stimulate economic development, recreation, and tourism in the region. They note that losing the Sea could cause economic and environmental decline, and could lead to air quality problems from exposed seabeds. Others contend that the Sea should not be restored. They argue that the Salton Sea is naturally declining, as it has throughout its geological history. Further, they note that countering this process will be costly and ultimately not worth the expense. They state that limited restoration funds should be used to restore other natural wetlands in California, such as the Sacramento-San Joaquin Bay Delta. The decline of the Salton Sea ecosystem is accelerating due to water transfers from agricultural lands to municipal water districts in San Diego under the terms of the Quantification Settlement Agreement, an agreement on how to share California’s apportionment of Colorado River water. The water transfers have resulted in less water flowing into the Salton Sea and accelerated increases in salinity and shoreline recession. According to some scientists, salinity levels may reach lethal levels for most fish and wildlife as soon as 2018. These predictions, along with the steadily declining ecosystem might provoke Congress to consider a larger role in restoration for the federal government. Congress may decide to address restoration by increasing the federal role in restoration efforts.  This could be done by funding existing federal authorities that address, or could address, restoring the ecosystem; authorizing federal participation and appropriations for implementing existing restoration plans; or authorizing a new comprehensive plan to be created that might involve participation from federal and non-federal stakeholders, similar to other restoration initiatives around the country. Congress might also decide not to address restoration of the Salton Sea ecosystem, or simply maintain the status quo of federal participation.

Potential Impacts of Reduced Inflows to the Salton Sea: Forecasting Non-market Damages

American Water Resources Association (AWRA) | September 28th, 2022

Programmatic Agreement among the U.S. Army Corps of Engineers and the California State Historic Preservation Officer and the Advisory Council on Historic Preservation and the Torres Martinez Desert Cahuilla Indians regarding Compliance with Section 106 of the National Historic Preservation Act for the Salton Sea Management Program

U.S. Army Corps of Engineers (USACE) | April 12th, 2024

Punctuated Sediment Discharge during Early Pliocene Birth of the Colorado River: Evidence from Regional Stratigraphy, Sedimentology, and Paleontology

Sedimentary Geology (Elsevier) | January 1st, 2018

The Colorado River in the southwestern U.S. provides an excellent natural laboratory for studying the origins of a continent-scale river system, because deposits th

The Colorado River in the southwestern U.S. provides an excellent natural laboratory for studying the origins of a continent-scale river system, because deposits that formed prior to and during river initiation are well exposed in the lower river valley and nearby basinal sink. This paper presents a synthesis of regional stratigraphy, sedimentology, and micropaleontology from the southern Bouse Formation and similar-age deposits in the western Salton Trough, which we use to interpret processes that controlled the birth and early evolution of the Colorado River. The southern Bouse Formation is divided into three laterally persistent members: basal carbonate, siliciclastic, and upper bioclastic members. Basal carbonate accumulated in a tide-dominated marine embayment during a rise of relative sea level between ~ 6.3 and 5.4 Ma, prior to arrival of the Colorado River. The transition to green claystone records initial rapid influx of river water and its distal clay wash load into the subtidal marine embayment at ~ 5.4–5.3 Ma. This was followed by rapid southward progradation of the Colorado River delta, establishment of the earliest through-flowing river, and deposition of river-derived turbidites in the western Salton Trough (Wind Caves paleocanyon) between ~ 5.3 and 5.1 Ma. Early delta progradation was followed by regional shut-down of river sand output between ~ 5.1 and 4.8 Ma that resulted in deposition of marine clay in the Salton Trough, retreat of the delta, and re-flooding of the lower river valley by shallow marine water that deposited the Bouse upper bioclastic member. Resumption of sediment discharge at ~ 4.8 Ma drove massive progradation of fluvial-deltaic deposits back down the river valley into the northern Gulf and Salton Trough. These results provide evidence for a discontinuous, start-stop-start history of sand output during initiation of the Colorado River that is not predicted by existing models for this system. The underlying controls on punctuated sediment discharge are assessed by comparing the depositional chronology to the record of global sea-level change. The lower Colorado River Valley and Salton Trough experienced marine transgression during a gradual fall in global sea level between ~ 6.3 and 5.5 Ma, implicating tectonic subsidence as the main driver of latest Miocene relative sea-level rise. A major fall of global sea level at 5.3 Ma outpaced subsidence and drove regional delta progradation, earliest flushing of Colorado River sand into the northern Gulf of California, and erosion of Bouse basal carbonate and siliciclastic members. The lower Colorado River valley was re-flooded by shallow marine waters during smaller changes in global sea level ~ 5.1–4.8 Ma, after the river first ran through it, which requires a mechanism to stop delivery of sand to the lower river valley. We propose that tectonically controlled subsidence along the lower Colorado River, upstream of the southern Bouse study area, temporarily trapped sediment and stopped delivery of sand to the lower river valley and northern Gulf of California for ~ 200–300 kyr. Massive progradation of the fluvial-deltaic system back down the river valley into the Salton Trough starting ~ 4.8–4.5 Ma apparently was driven by a huge increase in sediment discharge that overwhelmed the sediment-storage capacity of sub-basins along the lower river corridor and established the fully integrated river channel network.

Recent global decline in endorheic basin water storages

Nature Portfolio (Springer Nature) | November 30th, 2018

Endorheic (hydrologically landlocked) basins spatially concur with arid/semi-arid climates. Given limited precipitation but high potential evaporation, their water storag

Endorheic (hydrologically landlocked) basins spatially concur with arid/semi-arid climates. Given limited precipitation but high potential evaporation, their water storage is vulnerable to subtle flux perturbations, which are exacerbated by global warming and human activities. Increasing regional evidence suggests a probably recent net decline in endorheic water storage, but this remains unquantified at a global scale. By integrating satellite observations and hydrological modelling, we reveal that during 2002–2016 the global endorheic system experienced a widespread water loss of about 106.3 Gt yr−1, attributed to comparable losses in surface water, soil moisture and groundwater. This decadal decline, disparate from water storage fluctuations in exorheic basins, appears less sensitive to El Niño–Southern Oscillation-driven climate variability, which implies a possible response to longer-term climate conditions and human water management. In the mass-conserved hydrosphere, such an endorheic water loss not only exacerbates local water stress, but also imposes excess water on exorheic basins, leading to a potential sea level rise that matches the contribution of nearly half of the land glacier retreat (excluding Greenland and Antarctica). Given these dual ramifications, we suggest the necessity for long-term monitoring of water storage variation in the global endorheic system and the inclusion of its net contribution to future sea level budgeting.

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, todayâ€

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.