The Effect of a Receding Saline Lake (The Salton Sea) on Airborne Particulate Matter Composition

American Chemical Society (ACS) | July 12th, 2017

The composition of ambient particulate matter (PM) and its sources were investigated at the Salton Sea, a shrinking saline lake in California. To investigate the influenc

The composition of ambient particulate matter (PM) and its sources were investigated at the Salton Sea, a shrinking saline lake in California. To investigate the influence of playa exposure on PM composition, PM samples were collected during two seasons and at two sites around the Salton Sea. To characterize source composition, soil samples were collected from local playa and desert surfaces. PM and soil samples were analyzed for 15 elements using mass spectrometry and X-ray diffraction. The contribution of sources to PM mass and composition was investigated using Al-referenced enrichment factors (EFs) and source factors resolved from positive matrix factorization (PMF). Playa soils were found to be significantly enriched in Ca, Na, and Se relative to desert soils. PMF analysis resolved the PM10 data with four source factors, identified as Playa-like, Desert-like, Ca-rich, and Se. Playa-like and desert-like sources were estimated to contribute to a daily average of 8.9% and 45% of PM10 mass, respectively. Additionally, playa sources were estimated to contribute to 38–68% of PM10 Na. PM10 Se concentrations showed strong seasonal variations, suggesting a seasonal cycle of Se volatilization and recondensation. These results support the importance of playas as a source of PM mass and a controlling factor of PM composition.

The Effect of Declining Groundwater Levels on Supply Well Operations

University of California, Davis (UC Davis) | August 15th, 2016

This report explores the impact of droughts on domestic and irrigation well operations. Well completion reports and groundwater depth data obtained from the Department of

This report explores the impact of droughts on domestic and irrigation well operations. Well completion reports and groundwater depth data obtained from the Department of Water Resources were used in the analysis. The percentages of wells in which the top, middle or bottom of the screened interval became exposed above the pumping water level were calculated and implied maintenance or replacement costs were estimated. Increases in pumping costs from greater depths to groundwater were estimated as well. For our case study, we selected a 27 square mile area in Tulare County, where the California Department of Water Resources has determined that groundwater is in a state of critical overdraft and designated the basin as High Priority under the Sustainable Groundwater Management Act. Results indicate that for the 2015 drought, there was significant potential for incurring well maintenance and replacement costs as a result of drought conditions and water levels approaching critical points in the screened intervals. While the assumptions associated with the current method appear to result in overestimation of impacts, the current drought may have resulted in several million dollars in well maintenance and replacement costs. For irrigation wells that remained in operation, increased depths to groundwater would increase overall pumping costs. About $5.31 per acre ($1.7 per acre-foot) were estimated as increased pumping costs in the recent 2012-2015 drought. While these costs are not large on a per acre basis, they may be significant when incurred across large agricultural areas. This proof of concept analysis highlights the value of information on groundwater levels and well constructions for estimating impacts of droughts on long term groundwater pumping capacity and operation. This analysis can be extended for the entire Central Valley in an effort to quantify the impacts of drought and the importance of groundwater management.

The effect of reducing per capita water and energy uses on renewable water resources in the water, food and energy nexus

Nature Portfolio (Springer Nature) | May 9th, 2022

This study assesses the feedbacks between water, food, and energy nexus at the national level with a dynamic-system model, taking into account the qualitative and quantit

This study assesses the feedbacks between water, food, and energy nexus at the national level with a dynamic-system model, taking into account the qualitative and quantitative environmental water needs. Surface and groundwater resources are considered jointly in the water resources subsystem of this dynamic system. The developed model considers the effects of reducing the per capita use water and energy on its system’s components. Results indicate that due to feedbacks the changes in per capita uses of water and energy have indirect and direct effects. About 40% of the total water savings achieved by the per capita change policy was related to energy savings, in other words, it is an indirect saving. Implementation of per capita use reductions compensates for 9% of the decline of Iran’s groundwater reservoirs (non-renewable resources in the short term) that occur during the five-year study period. The Manageable and Exploitable Renewable Water Stress Index (MRWI) corresponding to water and energy savings equals 214.5%, which is better than its value under the current situation (which is equal to 235.1%).

The effect of the El Niño-Southern Oscillation on U.S. regional and coastal sea level

American Geophysical Union (AGU) | June 3rd, 2015

Although much of the focus on future sea level rise concerns the long-term trend associated with anthropogenic warming, on shorter time scales, internal climate variabil

Although much of the focus on future sea level rise concerns the long-term trend associated with anthropogenic warming, on shorter time scales, internal climate variability can contribute significantly to regional sea level. Such sea level variability should be taken into consideration when planning efforts to mitigate the effects of future sea level change. In this study, we quantify the contribution to regional sealevel of the El Niño-Southern Oscillation (ENSO). Through cyclostationary empirical orthogonal function analysis (CSEOF) of the long reconstructed sea level data set and of a set of U.S. tide gauges, two global modes dominated by Pacific Ocean variability are identified and related to ENSO and, by extension, the Pacific Decadal Oscillation. By estimating the combined contribution of these two modes to regional sealevel, we find that ENSO can contribute significantly on short time scales, with contributions of up to 20 cm along the west coast of the U.S. The CSEOF decomposition of the long tide gauge records around the U.S. highlights the influence of ENSO on the U.S. east coast. Tandem analyses of both the reconstructed and tidegauge records also examine the utility of the sea level reconstructions for near-coast studies.

The effect of urbanization on floods of different recurrence interval

American Geophysical Union (AGU) | June 3rd, 1975

Studies have shown that the urbanization of a catchment can drastically change the flood characteristics of a river. Published results are synthesized to show the g

Studies have shown that the urbanization of a catchment can drastically change the flood characteristics of a river. Published results are synthesized to show the general relationship between the increase in flood flows following urbanization and both the percentage of the basin paved and the flood recurrence interval. In general, (1) floods with a return period of a year or longer are not affected by a 5% paving of their catchment, (2) small floods may be increased by 10 times by urbanization, (3) floods with a return period of 100 yr may be doubled in size by a 30% paving of the basin, and (4) the effect of urbanization declines, in relative terms, as flood recurrence intervals increase.

The effects of aquatic area abundance, buffer, and hydrology on depressional wetland condition based on CRAM

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

The effects of artificial recharge on groundwater levels and water quality in the west hydrogeologic unit of the Warren Subbasin, San Bernardino County, California

U.S. Geological Survey (USGS) | November 4th, 2013

The effects of kaolin clay on the amphipod Eohaustorius estuarius: Part Two

San Francisco Estuary Institute (SFEI) | April 3rd, 2017

A number of lines-of-evidence suggest that the amphipod Eohaustorius estuarius has variable tolerance to clay in sediments. In Phase 1 of the current RMP special study, l

A number of lines-of-evidence suggest that the amphipod Eohaustorius estuarius has variable tolerance to clay in sediments. In Phase 1 of the current RMP special study, laboratory dose-response experiments were conducted in 2014 with kaolin clay to evaluate whether clay effects varied with amphipod size. The results indicated that smaller amphipods were more tolerant of clay than larger individuals. Average survival was 81%, 79%, and 65% for small, medium and large amphipods, respectively, in concentrations > 50% clay. As part of Phase 2 confirmation studies conducted in 2015-2016, the original kaolin dose-response experiments were repeated. Results of this experiment showed that average amphipod survival was 88%, 63%, and 41% for small, medium and large amphipods, respectively, in concentrations > 50% clay. Standard 96-hour reference toxicant tests with cadmium chloride (CdCl2) were conducted to determine whether there were size-specific differences in response to this metal reference toxicant. The CdCl2 median lethal concentrations (LC50s) for small, medium and large amphipods were 6.78, 5.13, and 4.63 mg/L, respectively. Responses of all three size classes to cadmium were within historic confidence intervals for this reference metal, and were not significantly different from one another based on overlapping confidence intervals. Additional experiments with high clay reference site sediments from San Francisco Bay were conducted to confirm the size related response with field sediments. The results confirm that use of smaller amphipods in routine monitoring of high clay sediments will reduce the influence of this factor on test results. 

The Effects of Salmon Fisheries on Southern Resident Killer Whales

National Marine Fisheries Service (NMFS) | November 30th, 2012

The Endangered Species Act (ESA) and Claims of Property Rights “Takings”

Congressional Research Service (CRS) | January 7th, 2013

The federal Endangered Species Act (ESA) has long been one of the major flash points in debates over government interference with property rights. This report outlines th

The federal Endangered Species Act (ESA) has long been one of the major flash points in debates over government interference with property rights. This report outlines the ESA provisions most relevant to the act’s impacts on private property and surveys the major ESA-relevant principles of Fifth Amendment takings law. The Takings Clause of the Fifth Amendment promises “just compensation” when government actions “take” property. The report then summarizes the court decisions on whether particular government actions (or inaction) based on the ESA “take” private property under the Fifth Amendment. The cases to date address several kinds of ESA impacts on private property: (1) restrictions on land uses that might adversely affect species listed as endangered or threatened, and mitigation conditions to offset the impacts of development; (2) administrative delays; (3) reductions in water delivery or allowable water diversion to preserve lake levels or instream flows needed by listed fish (currently the most active area of ESA takings litigation); (4) restrictions on the defensive measures a property owner may take to protect his/her property from listed animals; and (5) restrictions on commercial dealings in listed species. To date, only one of the 18 ESA-based takings cases disclosed by research, Tulare Lake Basin Water Storage District v. United States, has found a taking. However, two cases, Casitas Municipal Water District v. United States and Klamath Irrigation District v. United States, have yet to be finally resolved and may or may not result in holdings that takings occurred.