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A comparison of the taxonomic and trait structure of macroinvertebrate communities between the riffles and pools of montane headwater streams
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A comparison of the taxonomic and trait structure of macroinvertebrate communities between the riffles and pools of montane headwater streams
Hydrobiologica, Springer International Publishing | May 30, 2018...
Summary
Macroinvertebrate community taxonomic and trait structure showed consistent differences between riffles and pools across 12 headwater streams in the Sierra Nevada (California) even...

Macroinvertebrate community taxonomic and trait structure showed consistent differences between riffles and pools across 12 headwater streams in the Sierra Nevada (California) even as flows varied from wet to dry years and between seasons. Densities of Ephemeroptera, Plecoptera, Trichoptera, Elmidae, Orthocladiinae and Diamesinae midges, and mites were greater in riffles, whereas Tanypodinae, Chironominae, Sialis, and Pisidium were more abundant in pools. Pools had higher densities but estimated biomass was greater in riffles. Collector-gatherer and micropredator abundances were greater in pools whereas grazers, collector-filterers, and macropredators were more abundant in riffles. Stonefly shredders were most abundant in riffles but some caddis shredders were more abundant in pools. Trait state patterns were related to food resource and physical habitat differences between riffles and pools. Of the distinct pool–riffle differences we found among taxa, only about half conformed to expectations from the literature. Pool and riffle assemblages were most dissimilar at intermediate discharge and converged at low and high flows when one or the other habitat dominated. Bioassessment sampling will need to account for these flow-related differences. Benthic invertebrate communities in these mountain streams clearly differ between pools and riffles, but the relative extent of habitats and biological similarity shift with flow regime.

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Anthropogenic warming impacts on California snowpack during drought

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Anthropogenic warming impacts on California snowpack during drought
American Geophysical Union (AGU) | March 15, 2017...
Summary
Sierra Nevada climate and snowpack is simulated during the period of extreme drought from 2011 to 2015 and compared to an identical simulation...
Sierra Nevada climate and snowpack is simulated during the period of extreme drought from 2011 to 2015 and compared to an identical simulation except for the removal of the twentieth century anthropogenic warming. Anthropogenic warming reduced average snowpack levels by 25%, with middle‐to‐low elevations experiencing reductions between 26 and 43%. In terms of event frequency, return periods associated with anomalies in 4 year 1 April snow water equivalent are estimated to have doubled, and possibly quadrupled, due to past warming. We also estimate effects of future anthropogenic warmth on snowpack during a drought similar to that of 2011–2015. Further snowpack declines of 60–85% are expected, depending on emissions scenario. The return periods associated with future snowpack levels are estimated to range from millennia to much longer. Therefore, past human emissions of greenhouse gases are already negatively impacting statewide water resources during drought, and much more severe impacts are likely to be inevitable.

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Anthropogenic Warming Impacts on Today’s Sierra Nevada Snowpack and Flood Risk

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Anthropogenic Warming Impacts on Today’s Sierra Nevada Snowpack and Flood Risk
American Geophysical Union (AGU) | June 15, 2018...
Summary
This study investigates temperature impacts to snowpack and runoff‐driven flood risk over the Sierra Nevada during the extremely wet year of 2016–2017, which...
This study investigates temperature impacts to snowpack and runoff‐driven flood risk over the Sierra Nevada during the extremely wet year of 2016–2017, which followed the extraordinary California drought of 2011–2015. By perturbing near‐surface temperatures from a 9‐km dynamically downscaled simulation, a series of offline land surface model experiments explore how Sierra Nevada hydrology has already been impacted by historical anthropogenic warming and how these impacts evolve under future warming scenarios. Results show that historical warming reduced 2016–2017 Sierra Nevada snow water equivalent by 20% while increasing early‐season runoff by 30%. An additional one third to two thirds loss of snowpack is projected by the end of the century, depending on the emission scenario, with middle elevations experiencing the most significant declines. Notably, the number of days in the future with runoff exceeding 20 mm nearly doubles under a mitigation emission scenarios and triples under a business‐as‐usual scenario. A smaller snow‐to‐rain ratio, as opposed to increased snowmelt, is found to be the primary mechanism of temperature impacts to Sierra snowpack and runoff. These findings are consequential to the prevalence of early‐season floods in the Sierra Nevada. In the Feather River Watershed, historical warming increased runoff by over one third during the period of heaviest precipitation in February 2017. This suggests that historical anthropogenic warming may have exacerbated runoff conditions underlying the Oroville Dam spillway overflow that occurred in this month. As warming continues in the future, the potential for runoff‐based flood risk may rise even higher.

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California Water Plan 2013: North Lahontan Hydrologic Region
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California Water Plan 2013: North Lahontan Hydrologic Region
California Department of Water Resources (DWR) | October 30, 2016...
Summary
The North Lahontan Hydrologic Region (North Lahontan region) includes part of the western edge of the Great Basin, a large landlocked area that...
The North Lahontan Hydrologic Region (North Lahontan region) includes part of the western edge of the Great Basin, a large landlocked area that covers most of Nevada and northern Utah. The eastern drainages of the Cascade Range and the eastern Sierra Nevada, north of the Mono Lake drainage, make up the region. All surface water drains eastward toward Nevada. This hydrologic region extends about 270 miles from the Oregon border to the southern boundary of the Walker River drainage in Mono County (Figure NL-1). The region covers 6,122 square miles, about 4 percent of California’s total area, but is inhabited by only about 0.3 percent of the state’s population.

The region includes portions of Modoc, Lassen, Sierra, Nevada, Placer, El Dorado, Alpine, and Mono counties.

The region abounds with large, natural landscapes. The northern part is primarily arid high desert with relatively flat valleys at elevations of 4,000 to 5,000 feet. The eastern slopes of the Sierra Nevada comprise the central and southern portions of this region, which includes the California portion of the Lake Tahoe Basin and the western Great Basin. The major rivers of the region —Truckee, Carson, and Walker — carry the mountain snowmelt through California into Nevada. Mountain peaks up to 12,279 feet from the western boundary of the region.

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California’s Fourth Climate Change Assessment Statewide Summary Report

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California’s Fourth Climate Change Assessment Statewide Summary Report
Governor's Office of Planning and Research, California Energy Commission (CEC), California Natural Resources Agency | August 27, 2018...
Summary
California’s Fourth Climate Change Assessment (Fourth Assessment) advances actionable science that serves the growing needs of state and local-level decision-makers from a variety...

California’s Fourth Climate Change Assessment (Fourth Assessment) advances actionable science that serves the growing needs of state and local-level decision-makers from a variety of sectors. This cutting-edge research initiative is comprised of a wide-ranging body of technical reports, including rigorous, comprehensive climate change scenarios at a scale suitable for illuminating regional vulnerabilities and localized adaptation strategies in California; datasets and tools that improve integration of observed and projected knowledge about climate change into decision- making; and recommendations and information to directly inform vulnerability assessments and adaptation strategies for California’s energy sector, water resources and management, oceans and coasts, forests, wildfires, agriculture, biodiversity and habitat, and public health. In addition, these technical reports have been distilled into summary reports and a brochure, allowing the public and decision-makers to easily access relevant findings from the Fourth Assessment.

Click here for key findings brochure

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Causes of the Extreme Dry Conditions over California During Early 2013

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Causes of the Extreme Dry Conditions over California During Early 2013
American Meteorological Society (AMS) | September 30, 2014...
Summary
The state of California experienced extreme dry conditions during early 2013. In particular, January and February received 28% and 15%, respectively, of their...

The state of California experienced extreme dry conditions during early 2013. In particular, January and February received 28% and 15%, respectively, of their normal monthly rainfall. When January and February are combined, January/ February 2013 is ranked as the driest of the period 1895–2014. Such large precipitation deficits exerted enormous stress on water resources in an already high water-demand region. Thus, it is of practical importance to investigate the causes of this extreme climate event so as to assess its predictability.

*Chapter 3, Explaining Extreme Events of 2013 from a Climate Perspective, Bull. Amer. Meteor. Soc., 95 (9)

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Climate and landscape drive the pace and pattern of conifer encroachment into subalpine meadows

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Climate and landscape drive the pace and pattern of conifer encroachment into subalpine meadows
Ecological Applications, Ecological Society of America | May 8, 2018...
Summary
Mountain meadows have high biodiversity and help regulate stream water release following the snowmelt pulse. However, many meadows are experiencing woody plant encroachment,...

Mountain meadows have high biodiversity and help regulate stream water release following the snowmelt pulse. However, many meadows are experiencing woody plant encroachment, threatening these ecosystem services. While there have been field surveys of individual meadows and remote sensing‐based landscape‐scale studies of encroachment, what is missing is a broad‐scale, ground‐based study to understand common regional drivers, especially at high elevations, where land management has often played a less direct role. With this study, we ask: What are the climate and landscape conditions conducive to woody plant encroachment at the landscape scale, and how has historical climate variation affected tree recruitment in subalpine meadows over time? We measured density of encroaching trees across 340 subalpine meadows in the central Sierra Nevada, California, USA, and used generalized additive models (GAMs) to determine the relationship between landscape‐scale patterns of encroachment and meadow environmental properties. We determined ages of trees in 30 survey meadows, used observed climate and GAMs to model the relationship between timing of recruitment and climate since the early 1900s, and extrapolated recruitment patterns into the future using downscaled climate scenarios. Encroachment was high among meadows with lodgepole pine (Pinus contorta Douglas ex Loudon var. murrayana (Balf.) Engelm.) in the immediate vicinity, at lower elevations, with physical conditions favoring strong soil drying, and with maximum temperatures above or below average. Climatic conditions during the year of germination were unimportant, with tree recruitment instead depending on a 3‐yr seed production period prior to germination and a 6‐yr seedling establishment period following germination. Recruitment was high when the seed production period had high snowpack, and when the seedling establishment period had warm summer maximum temperatures, high summer precipitation, and high snowpack. Applying our temporal model to downscaled output from four global climate models indicated that the average meadow will shift to forest by the end of the 21st century. Sierra Nevada meadow encroachment by conifers is ubiquitous and associated with climate conditions increasingly favorable for tree recruitment, which will lead to substantial changes in subalpine meadows and the ecosystem services they provide.

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Effective Implementation of the Public Trust Doctrine in California Water Resources Decision-Making: A View From the Bench

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Effective Implementation of the Public Trust Doctrine in California Water Resources Decision-Making: A View From the Bench
University of California at Berkeley, School of Law | April 12, 2012...
Summary
Forty years ago, in his seminal law review article on the public trust doctrine, Professor Joseph L. Sax suggested that “citizens seeking to...

Forty years ago, in his seminal law review article on the public trust doctrine, Professor Joseph L. Sax suggested that “citizens seeking to develop a comprehensive legal approach to resource management problems” could use the public trust doctrine to obtain “effective judicial intervention” where “legislative response and administrative action” had been inconsistent.

Of course, water is one of the natural resources to which the public trust doctrine is, and always has been, particularly applicable. And yet, it was not until ten years after Professor Sax published his article that Professor Ralph W. Johnson first predicted an impending “collision” between “[t]he public trust doctrine and the appropriative water rights system . . . in the West.” The imminence of that collision — in California at least — was due in no small part to the National Audubon Society’s then-pending suit against the Department of Water and Power of the City of Los Angeles (“L.A. Water and Power”) to limit diversions from the streams feeding Mono Lake. That suit, which was a prime example of the sort of public interest litigation Professor Sax had advocated in his article, led to the California Supreme Court’s seminal decision in National Audubon, in which the court announced that “[t]he state has an affirmative duty to take the public trust into account in the planning and allocation of water resources, and to protect the public trust uses whenever feasible.”

Today, twenty-eight years after the decision in National Audubon and more than forty years after Professor Sax’s article, what have we learned about the use of the public trust doctrine in water resources decision-making in California? Has it been an effective tool for obtaining judicial intervention in the decision-making process, as Professor Sax suggested it could be? And, more importantly, is judicial intervention the best way to effectuate and protect public trust values in the state’s water resources?

Those are some of the questions I seek to answer in this Article.

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Environmental Justice Program Implementation for Lahontan Region
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Environmental Justice Program Implementation for Lahontan Region
Lahontan Regional Water Quality Control Board | January 30, 2015...
Summary
The Lahontan Regional Water Quality Control Board (Lahontan Water Board) reviewed how environmental justice (EJ) is conducted in the region and examined new...
The Lahontan Regional Water Quality Control Board (Lahontan Water Board) reviewed how environmental justice (EJ) is conducted in the region and examined new ways to improve our efforts to benefit the disadvantaged communities in our region. The challenges faced by disadvantaged communities (DACs) in the Lahontan region are unique and often different than other DACs in more urban regions. This report provides an assessment of existing efforts to help DACs and catalogs EJ concerns. In addition, the report includes recommendations to enhance DACs participation in the regulatory process, expand access to funding and technical assistance, and improve water quality and drinking water.

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Examining the Contribution of the Observed Global Warming Trend to the California Droughts of 2012/13 and 2013/14

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Examining the Contribution of the Observed Global Warming Trend to the California Droughts of 2012/13 and 2013/14
American Meteorological Society (AMS) | September 30, 2014...
Summary
In this study, we examine the November–February California droughts of 2012/13 and 2013/14. During 2013/14, California had its warmest and third driest rainy...

In this study, we examine the November–February California droughts of 2012/13 and 2013/14. During 2013/14, California had its warmest and third driest rainy season on record (1895–2014), while the 2012/13 season registered as the 45th warmest and 38th driest (Vose et al. 2014). The 2013 January–December calendar year was the driest on record (Water CA 2014). These consecutive below-normal seasons conspired with warm temperatures to reduce California’s snowpack to the second lowest level since 1960, when recording began, with snowpack at 24% of normal (Water CA 2014). Between January 2013 and January 2014, satellite observations documented dramatic snowpack-related land cover change (NASA Earth Observatory 2014): in 2014, the Cascade, Sierra Nevada, and Coastal ranges were almost completely devoid of snow. In February and March of 2014, air temperatures were extremely warm (NOAA NCDC 2014; HPRC 2014), and U.S. Geological Survey (USGS) observations indicated extreme or moderate hydrologic drought (USGS 2014) and high levels of vegetation stress (VegDRI 2014). The state declared a drought emergency (NIDIS 2014). While it is too soon to assess the full impact of the 2012/13 and 2013/14 California droughts, they seem likely to substantially impact the state’s ability to generate hydrologic power, support agriculture, reduce the risk of forest and bush fires, and protect fragile ecosystems (Huffington Post 2014).

*Chapter 4, Explaining Extreme Events of 2013 from a Climate Perspective, Bull. Amer. Meteor. Soc., 95 (9)

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