A 350,000-year history of groundwater recharge in the southern Great Basin, USA

Nature Portfolio (Springer Nature) | March 31st, 2023

Estimating groundwater recharge under various climate conditions is important for predicting future freshwater availability. This is especially true for the water-limited

Estimating groundwater recharge under various climate conditions is important for predicting future freshwater availability. This is especially true for the water-limited region of the southern Great Basin, USA. To investigate the response of groundwater recharge to different climate states, we calculate the paleo recharge to a groundwater basin in southern Nevada over the last 350,000 years. Our approach combines a groundwater model with paleo-water-table data from Devils Hole cave. The minimum water-table during peak interglacial conditions was more than 1.6 m below modern levels, representing a recharge decline of less than 17% from present-day conditions. During peak glacial conditions, the water-table elevation was at least 9.5 m above modern levels, representing a recharge increase of more than 233–244% compared to present-day conditions. The elevation of the Devils Hole water-table is 3–4 times more sensitive to groundwater recharge during dry interglacial periods, compared to wet glacial periods. This study can serve as a benchmark for understanding long-term effects of past and future climate change on groundwater resources.

A 450-year record of environmental change from Castle Lake, California (USA), inferred from diatoms and organic geochemistry

Journal of Paleolimnology (Springer) | November 11th, 2020

A 39-cm sediment core from Castle Lake, California (USA) spans the last ~ 450 years and was analyzed for diatoms and organic geochemistry (δ15N, δ13C, and C:N), wi

A 39-cm sediment core from Castle Lake, California (USA) spans the last ~ 450 years and was analyzed for diatoms and organic geochemistry (δ15N, δ13C, and C:N), with the goal of determining sensitivity to natural climate variation and twentieth century anthropogenic effects. Castle Lake is a subalpine, nitrogen-limited lake with ~ 5 months of annual ice cover. Human impacts include light recreational use, past fish stocking, and experimental use by the Castle Lake Research Station. The base of the core (below 32 cm; pre mid-1700s) represents the period of maximum ice cover. In contrast, the end of the Little Ice Age (mid 1700s–early 1800s) is dominated by cyclotelloids (mostly Discostella stelligera), indicating significant open-water periods, a condition that persisted into the early 1900s. Cyclotelloids began to decline in the 1960s and were replaced by the Fragilaria tenera grp. (peak in 1970s), succeeded by Asterionella formosa (peak ~ 2010), and accompanied by a reduction in δ15N values and a decrease in C:N that may represent increased atmospheric nitrogen deposition. Another anthropogenic signal was discerned in the core and was interpreted to be the result of an ammonium nitrate fertilization experiment of the epilimnion that was conducted in 1980 and 1981. This signal was manifested in the core largely by a negative excursion in δ15N, possibly caused by fractionation during denitrification in surface sediment. A phytoplankton monitoring dataset collected by the Castle Lake Research Station from 1967 to 1984 corroborates the timing of increased araphid euplanktonic species in the 1970s, and increases in two benthic diatoms (Staurosirella pinnata and Tabellaria fenestrata), entrained in the phytoplankton tows during the experimentation years. Both ice cover and nitrogen addition appear to be strong drivers that affected the lake diatoms, although additional drivers, such as fish stocking and associated cascade effects need further exploration. These data will be helpful for interpreting longer core records from Castle Lake, should the opportunity arise, as well as cores from similar systems in the region.

A Case Study in Interstate Resource Management: The California-Nevada Water Controversy, 1865-1955

University of California, Davis (UC Davis) | May 1st, 1973

A Delta Renewed: A Guide to Science-Based Ecological Restoration in the Sacramento-San Joaquin Delta

San Francisco Estuary Institute (SFEI) | November 1st, 2016

A Delta Renewed and the larger Delta Landscapes project are part of an ongoing effort to address these critically important challenges. They provide guidance for restora

A Delta Renewed and the larger Delta Landscapes project are part of an ongoing effort to address these critically important challenges. They provide guidance for restoration that renews critical functions over time without having major negative impacts on the current human enterprise in the Delta area and on other areas dependent on its services. The idea is to determine the most efficient ways to recover Delta functioning so that human benefits are maintained, while investing in process-based recovery of landscape functions. The scientists working on this project assume that this goal is best achieved if we can understand how the Delta functioned before major European modification. We can then use that knowledge as a guide to developing a diverse portfolio of habitats and connections that might sustain native species, and the attributes of a healthy Delta into the future. The effort to reconstruct the Delta of the early 1800s has been challenging, but is now completed. The next step is to devise management scenarios that will recover important functions and native species where possible. There is no intent to try to recreate the Delta of the past. That is impossible without sacrificing our objective of maintaining and even improving the human enterprises now present. What is essential now is to obtain general agreement among all of the stakeholders, which includes all citizens of California, that the Delta should be managed for the benefit of people and wildlife in a sustainable way. Given the uncertainties inherent in any large-scale reconciliation effort, there is a real need to appreciate the complex interactions and inter-dependencies that characterize the various components of the Delta landscape. There is also a need to understand the uncertainties of future climate change and to recognize the diversity of needs among our fellow citizens. Our hopes for success will ultimately depend on generating a spirit of cooperation for the common good. It won’t be easy, but the stakes are high. The Delta Landscapes project is dedicated to that goal.

A Delta Transformed: Ecological Functions, Spatial Metrics, and Landscape Change in the Sacramento-San Joaquin Delta

San Francisco Estuary Institute (SFEI) | October 1st, 2014

In A Delta Transformed, completed in 2014, SFEI researchers used the spatial data generated in the Delta Historical Ecology Investigation, as well as updated modern veget

In A Delta Transformed, completed in 2014, SFEI researchers used the spatial data generated in the Delta Historical Ecology Investigation, as well as updated modern vegetation and land cover datasets, to carry out detailed analyses of how the Delta landscape has been altered since the early-1800s. By quantifying changes in metrics relevant to native wildlife (such as the extent and timing of inundation, habitat patch sizes, length of channel networks), the report provides a foundation for defining, designing, and evaluating landscapes that support desirable ecological functions in the future. See more at: http://www.sfei.org/projects/delta-landscapes-project#sthash.RryQdaII.dpuf

A Historical Perspective of the Interagency Ecological Program: Bridging Multi-Agency Studies into Ecological Understanding of the Sacramento-San Joaquin Delta and Estuary for 40 Years

Interagency Ecological Program (IEP) | February 8th, 2013

The Interagency Ecological Program (IEP) has been in existence in some form for almost 50 years. As the San Francisco Estuary evolved due to natural and man-caused pertur

The Interagency Ecological Program (IEP) has been in existence in some form for almost 50 years. As the San Francisco Estuary evolved due to natural and man-caused perturbations, the IEP has responded by creating and re-creating itself to ensure the best understanding of the Estuary as it was influenced by water project implementation. The goal of the IEP has always been to provide this understanding to managers responsible for water project implementation in the most protective and efficient manner given social, political, and environmental constraints. On the whole, IEP has done an outstanding job of providing consistently useful data and information in a highly complex environment. As new programs and constraints are developed to cope with the ever changing natural environment and demands of society, an understanding of the history of IEP is valuable, and to learn from past experience is wise. This descriptive history is meant to document in some detail the development, strengths, and weaknesses of this one-of-a-kind multi-agency consortium that has attempted to bridge the gap between water management and estuarine science in the most significant Estuary on the west coast of North America. Sources of information for this account are personal interviews with program participants, annual reports, IEP Newsletters, coordinator meeting summaries, director meeting summaries, management team meeting notes, and personal experiences of the author. This history may err on the side of excessive detail, but that has been intentional; the author believes it is important to have detailed information available in a single reference so that interested parties can readily obtain knowledge about IEP. Some individuals may not want to read the entire report, but can easily be guided to topics of interest by consulting Appendix A, which lists significant events that influenced the IEP by page number in the report.

A three-dimensional numerical model of predevelopment conditions in the Death Valley regional ground-water flow system, Nevada and California

U.S. Geological Survey (USGS) | July 1st, 2002

Artesian Wells at Pomoma, Cal

Scientific American | January 10th, 1885

N0 portion of the State has made such a rapid progress in the development of its natural resources as have Los Angeles and San Bernardino counties during the past few

N0 portion of the State has made such a rapid progress in the development of its natural resources as have Los Angeles and San Bernardino counties during the past few years. In the fall of 1882, just two years ago, the Pomona Land and Water Company was incorporated for the purpose of developing and placing upon the market in small tracts the virgin lands of this fertile valley.

Atmospheric circulation during Holocene lake stands in the Mojave Desert: evidence of regional climate change

Nature Portfolio (Springer Nature) | September 7th, 1989

It is commonly thought that the climate conditions that supported lakes over a period of years in the Mojave Desert in southern California, only existed before 8,

It is commonly thought that the climate conditions that supported lakes over a period of years in the Mojave Desert in southern California, only existed before 8,000 yr BP and that the environment has been arid since. Here we look at a drill core in the Silver Lake playa at the terminus of the Mojave River and find Holocene lake deposits which indicate that shallow lakes existed for at least a few decades. These deposits were radiocarbon dated at 3620 ±70 and 390 ± 90 yr BP, corresponding to the early Neo-glacial and the 'little ice age' respectively. To identify the conditions necessary to produce these Holocene lake events we have examined the modern climate and hydrological patterns that produce ephemeral lakes in this usually arid watershed. Available data indicate that there is a link between anomalous winter atmospheric conditions over the North Pacific and Mojave River floods that produced ephemeral lakes in the Silver Lake playa and that the Mojave River filters out small to medium floods and allows only the extreme floods to reach the terminal playa and leave a record of the anomalous conditions. We suggest that the late Holocene lakes may have resulted from persistent similar atmospheric circulation patterns and winter floods.

Atmospheric river activity during the late Holocene exceeds modern range of variability in California

Nature Portfolio (Springer Nature) | April 25th, 2024

Atmospheric rivers are associated with some of the largest flood-producing precipitation events in western North America, particularly California. Insight into past extre

Atmospheric rivers are associated with some of the largest flood-producing precipitation events in western North America, particularly California. Insight into past extreme precipitation can be reconstructed from sedimentary archives on millennial timescales. Here we document atmospheric river activity near Leonard Lake, California, over 3,200 years, using a key metric of atmospheric river intensity, that is silicon/aluminum enriched layers that are highly correlated with modern records of integrated vapor transport. The late twentieth century had the highest median integrated vapor transport since the onset of the Medieval Climate Anomaly, with integrated vapor transport increasing during the Little Ice Age. The reconstruction suggests California has experienced pluvial episodes that exceeded any in the meteorologic instrumental era, with the largest episodes occurring two and three millennia ago. These results provide critical data to help avoid underestimation of potential risks and aid future planning scenarios.