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.

The Enduring Role of Tribes in the Colorado River Basin

Water and Tribes Initiative | July 1st, 2019

The purpose of this policy brief is to explain the origin, rationale, and purpose of the Water & Tribes Initiative in the Colorado River Basin. As explained more fully be

The purpose of this policy brief is to explain the origin, rationale, and purpose of the Water & Tribes Initiative in the Colorado River Basin. As explained more fully below, the long-term objectives of this Initiative are to: • Enhance the capacity of tribes to advance their needs and interests with respect to water management in the basin; and • Advance sustainable water management through collaborative decision-making.

The Essential Role of Local Context in Shaping Risk and Risk Reduction Strategies for Snowmelt-Dependent Irrigated Agriculture

American Geophysical Union (AGU) | June 11th, 2024

The estimated impact of California’s urban water conservation mandate on electricity consumption and greenhouse gas emissions

Environmental Research Letters (IOP) | January 12th, 2018

In April 2015, the Governor of California mandated a 25% statewide reduction in water consumption (relative to 2013 levels) by urban water suppliers. The more tha

In April 2015, the Governor of California mandated a 25% statewide reduction in water consumption (relative to 2013 levels) by urban water suppliers. The more than 400 public water agencies affected by the regulation were also required to report monthly progress towards the conservation goal to the State Water Resources Control Board. This paper uses the reported data to assess how the water utilities have responded to this mandate and to estimate the electricity savings and greenhouse gas (GHG) emissions reductions associated with reduced operation of urban water infrastructure systems. The results show that California succeeded in saving 524,000 million gallons (MG) of water (a 24.5% decrease relative to the 2013 baseline) over the mandate period, which translates into 1830 GWh total electricity savings, and a GHG emissions reduction of 521,000 metric tonnes of carbon dioxide equivalents (MT CO2e). For comparison, the total electricity savings linked to water conservation are approximately 11% greater than the savings achieved by the investor-owned electricity utilities’ efficiency programs for roughly the same time period, and the GHG savings represent the equivalent of taking about 111 000 cars off the road for a year. These indirect, large-scale electricity and GHG savings were achieved at costs that were competitive with existing programs that target electricity and GHG savings directly and independently. Finally, given the breadth of the results produced, we built a companion website, called H2Open, to this research effort that allows users to view and explore the data and results across scales, from individual water utilities to the statewide summary.

The Evaporative Demand Drought Index. Part I: Linking Drought Evolution to Variations in Evaporative Demand

American Meteorological Society (AMS) | March 1st, 2016

Many operational drought indices focus primarily on precipitation and temperature when depicting hydroclimatic anomalies, and this perspective can be augmented by analys

Many operational drought indices focus primarily on precipitation and temperature when depicting hydroclimatic anomalies, and this perspective can be augmented by analyses and products that reflect the evaporative dynamics of drought. The linkage between atmospheric evaporative demand E0 and actual evapotranspiration (ET) is leveraged in a new drought index based solely on E0—the Evaporative Demand Drought Index (EDDI). EDDI measures the signal of drought through the response of E0 to surface drying anomalies that result from two distinct land surface–atmosphere interactions: 1) a complementary relationship between E0 and ET that develops under moisture limitations at the land surface, leading to ET declining and increasing E0, as in sustained droughts, and 2) parallel ET and E0 increases arising from increased energy availability that lead to surface moisture limitations, as in flash droughts. To calculate EDDI from E0, a longterm, daily reanalysis of reference ET estimated from the American Society of Civil Engineers (ASCE) standardized reference ET equation using radiation and meteorological variables from the North American Land Data Assimilation System phase 2 (NLDAS-2) is used. EDDI is obtained by deriving empirical probabilities of aggregated E0 depths relative to their climatologic means across a user-specific time period and normalizing these probabilities. Positive EDDI values then indicate drier-than-normal conditions and the potential for drought. EDDI is a physically based, multiscalar drought index that that can serve as an indicator of both flash and sustained droughts, in some hydroclimates offering early warning relative to current operational drought indices. The performance of EDDI is assessed against other commonly used drought metrics across CONUS in Part II.

The evolution of dam induced river fragmentation in the United States

Nature Portfolio (Springer Nature) | June 28th, 2023

The evolution of human population distance to water in the USA from 1790 to 2010

Nature Portfolio (Springer Nature) | January 25th, 2019

Human societies evolved alongside rivers, but how has the relationship between human settlement locations and water resources evolved over time? We conducted a dynamic 

Human societies evolved alongside rivers, but how has the relationship between human settlement locations and water resources evolved over time? We conducted a dynamic analysis in the conterminous US to assess the coevolution of humans and water resources from 1790 to 2010. Here we show that humans moved closer to major rivers in pre-industrial periods but have moved farther from major rivers after 1870, demonstrating the dynamics of human reliance on rivers for trade and transport. We show that humans were preferentially attracted to areas overlying major aquifers since industrialization due to the emergent accessibility of groundwater in the 20th century. Regional heterogeneity resulted in diverse trajectories of settlement proximity to major rivers, with the attractiveness of rivers increasing in arid regions and decreasing in humid areas. Our results reveal a historical coevolution of human-water systems, which could inform water management and contribute to societal adaptation to future climate change.

The Evolution of Metropolitan’s Agricultural Partnerships

Metropolitan Water District of Southern California (MWD) | August 5th, 2022