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At least 217 records · Page 12Linked to original sources
USGS1995

Evidence of impaired reproduction by Western mosquitofish inhabiting seleniferous agricultural drainwater

Western mosquitofish Gambusia affinis from the San Luis Drain (SLD), a major conveyance system for seleniferous agricultural subsurface (tile) drainage water in the San Joaquin Valley, California, experienced lower reproductive success than did mosquitofish from a nearby reference area (Pond 26 at the Volta Wildlife Area, VOLTA) that had no history of receiving tile drainage. At birth, mean survival of SLD fry was 70% in 1984 and 77% in 1985, whereas mean survival of VOLTA fry was greater than 99% in 1984 and 97% in 1985. Measurements of total length (TL) of offspring born to SLD females in 1985 showed that stillborn fry (mean TL, 7.5 mm) were significantly shorter than live fry (mean TL, 9.4 mm). In addition, most stillborn fry were at earlier stages of development (contained prominent yolk sacs or occasionally resembled eyed embryos) than most live fry (yolk sacs were fully resorbed). In comparison, stillborn and live fry born to VOLTA females did not differ significantly in TL (mean for stillborn fry, 7.1 mm; mean for live fry, 7.5 mm), and nearly all fry had resorbed their yolk sacs. Mosquitofish from the SLD contained over 100 μg/g (whole‐body concentration in dry weight) of selenium, whereas those from VOLTA averaged 1.5 μg/g. Although experiments are still needed to establish cause and effect, the high incidence of abnormal births of mosquitofish from the SLD is seemingly a response to selenium toxicity.

California↗
USGS1963

Geology, hydrology, and water supply of Edwards Air Force Base, Kern County, California

Edwards Air Force Base occupies the northern part of Antelope Valley, California. As a result of large-scale and increasing agricultural pumping in the valley, the net draft has exceeded the perennial supply since about 1930 and was about 170,000 acre-feet in 1951--at least three times the estimated yield. As a result, there has been a continuing depletion of ground water stored in all the unconsolidated deposits, including the principal aquifers contained in the younger and older alluvium.

Open-File Report↗
USGS2014

Land subsidence, groundwater levels, and geology in the Coachella Valley, California, 1993-2010

Land subsidence associated with groundwater-level declines has been investigated by the U.S. Geological Survey in the Coachella Valley, California, since 1996. Groundwater has been a major source of agricultural, municipal, and domestic supply in the valley since the early 1920s. Pumping of groundwater resulted in water-level declines as much as 15 meters (50 feet) through the late 1940s. In 1949, the importation of Colorado River water to the southern Coachella Valley began, resulting in a reduction in groundwater pumping and a recovery of water levels during the 1950s through the 1970s. Since the late 1970s, demand for water in the valley has exceeded deliveries of imported surface water, resulting in increased pumping and associated groundwater-level declines and, consequently, an increase in the potential for land subsidence caused by aquifer-system compaction. Global Positioning System (GPS) surveying and Interferometric Synthetic Aperture Radar (InSAR) methods were used to determine the location, extent, and magnitude of the vertical land-surface changes in the southern Coachella Valley during 1993–2010. The GPS measurements taken at 11 geodetic monuments in 1996 and in 2010 in the southern Coachella Valley indicated that the elevation of the land surface changed –136 to –23 millimeters (mm) ±54 mm (–0.45 to –0.08 feet (ft) ±0.18 ft) during the 14-year period. Changes at 6 of the 11 monuments exceeded the maximum expected uncertainty of ±54 mm (±0.18 ft) at the 95-percent confidence level, indicating that subsidence occurred at these monuments between June 1996 and August 2010. GPS measurements taken at 17 geodetic monuments in 2005 and 2010 indicated that the elevation of the land surface changed –256 to +16 mm ±28 mm (–0.84 to +0.05 ft ±0.09 ft) during the 5-year period. Changes at 5 of the 17 monuments exceeded the maximum expected uncertainty of ±28 mm (±0.09 ft) at the 95-percent confidence level, indicating that subsidence occurred at these monuments between August 2005 and August 2010. At each of these five monuments, subsidence rates were about the same between 2005 and 2010 as between 2000 and 2005. InSAR measurements taken between June 27, 1995, and September 19, 2010, indicated that the land surface subsided from about 220 to 600 mm (0.72 to 1.97 ft) in three areas of the Coachella Valley: near Palm Desert, Indian Wells, and La Quinta. In Palm Desert, the average subsidence rates increased from about 39 millimeters per year (mm/yr), or 0.13 foot per year (ft/yr), during 1995–2000 to about 45 mm/yr (0.15 ft/yr) during 2003–10. In Indian Wells, average subsidence rates for two subsidence maxima were fairly steady at about 34 and 26 mm/yr (0.11 and 0.09 ft/yr) during both periods; for the third maxima, average subsidence rates increased from about 14 to 19 mm/yr (0.05 to 0.06 ft/yr) from the first to the second period. In La Quinta, average subsidence rates for five selected locations ranged from about 17 to 37 mm/yr (0.06 to 0.12 ft/yr) during 1995–2000; three of the locations had similar rates during 2003–mid-2009, while the other two locations had increased subsidence rates. Decreased subsidence rates were calculated throughout the La Quinta subsidence area during mid-2009–10, however, and uplift was observed during 2010 near the southern extent of this area. Water-level measurements taken at wells near the subsiding monuments and in the three subsiding areas shown by InSAR generally indicated that the water levels fluctuated seasonally and declined annually from the early 1990s, or earlier, to 2010; some water levels in 2010 were at the lowest levels in their recorded histories. An exception to annually declining water levels in and near subsiding areas was observed beginning in mid-2009 in the La Quinta subsidence area, where recovering water levels coincided with increased recharge operations at the Thomas E. Levy Recharge Facility; decreased pumpage also could cause groundwater levels to recover. Subsidence concomitant with declining water levels and land-surface uplift concomitant with recovering water levels indicate that aquifer-system compaction could be causing subsidence. If the stresses imposed by the historically lowest water levels exceeded the preconsolidation stress, the aquifer-system compaction and associated land subsidence could be permanent.

California↗
USGS2020

Pesticide concentrations associated with augmented flow pulses in the Yolo Bypass and Cache Slough Complex, California

Surface-water and suspended-sediment samples were collected and analyzed by the U.S. Geological Survey for multiple current-use pesticides and pesticide degradates approximately every 2 weeks at up to five sites in the Yolo Bypass and Cache Slough Complex before, during, and after augmented flow pulses in summer and fall 2016 and 2018 as well as during ambient flow conditions in summer and fall 2017 (no flow pulse). In 2016, augmented flows occurred during the summer (July) and required the pumping of Sacramento River water by local Reclamation Districts into the Colusa Basin Drain and Yolo Bypass Toe Drain. In contrast, augmented flows in 2018 occurred in the fall (August–September) and used agricultural tailwater (primarily rice field discharge water) to create the flow pulse. Water samples were analyzed by the U.S. Geological Survey for a suite of 175 current-use pesticides and pesticide degradates using gas chromatography with mass spectrometry and liquid chromatography with tandem mass spectrometry laboratory methods. Suspended sediments filtered from the water samples were analyzed for 143 pesticides and degradates by gas chromatography with mass spectrometry. During the study, 53 pesticides were detected, and all the samples contained mixtures of multiple pesticides at concentrations ranging from below method detection limits to 8,780 nanograms per liter. Pesticides used in growing rice were the dominant pesticides present at four of the five sites sampled and urban-use pesticides dominated at the remaining site. Overall, total pesticide concentrations tended to be higher at sites in the northern part of the Yolo Bypass and lower at southern sites, except for the farthest downstream site which received additional pesticide inputs from the Sacramento River. Flow-pulse water source influenced total pesticide concentrations in the Yolo Bypass and Cache Slough Complex, and the highest total pesticide concentrations at each site were detected either immediately before or during the flow pulse generated with agricultural tailwater in 2018. Data gathered during this study will aid the California Department of Water Resources and other agencies working in the region in adaptively managing pulse flows in the Yolo Bypass and Cache Slough Complex, as one of several California Natural Resources Agency’s Delta Smelt Resiliency strategies.

California↗
USGS2015

Assessment of interim flow water-quality data of the San Joaquin River restoration program and implications for fishes, California, 2009-11

After more than 50 years of extensive water diversion for urban and agriculture use, a major settlement was reached among the U.S. Departments of the Interior and Commerce, the Natural Resources Defense Council, and the Friant Water Users Authority in an effort to restore the San Joaquin River. The settlement received Federal court approval in October 2006 and established the San Joaquin River Restoration Program, a multi-agency collaboration between State and Federal agencies to restore and maintain fish populations, including Chinook salmon, in the main stem of the river between Friant Dam and the confluence with the Merced River. This is to be done while avoiding or minimizing adverse water supply effects to all of the Friant Division contractors that could result from restoration flows required by the settlement. The settlement stipulates that water- and sediment-quality data be collected to help assess the restoration goals. This report summarizes and evaluates water-quality data collected in the main stem of the San Joaquin River between Friant Dam and the Merced River by the U.S. Bureau of Reclamation for the San Joaquin River Restoration Program during 2009-11. This summary and assessment consider sampling frequency for adequate characterization of variability, sampling locations for sufficient characterization of the San Joaquin River Restoration Program restoration reach, sampling methods for appropriate media (water and sediment), and constituent reporting limits. After reviewing the water- and sediment-quality results for the San Joaquin River Restoration Program, several suggestions were made to the Fisheries Management Work Group, a division of the San Joaquin River Restoration Program that focuses solely on the reintroduction strategies and health of salmon and other native fishes in the river. Water-quality results for lead and total organic carbon exceeded the Surface Water Ambient Monitoring Program Basin Plan Objectives for the San Joaquin Basin, and results for copper exceeded the U.S. Environmental Protection Agency Office of Pesticide Programs' aquatic-life chronic and acute benchmarks for invertebrates. One sediment sample contained detections of pyrethroid pesticides bifenthrin, lambda-cyhalothrin, and total permethrin at concentrations above published chronic toxicity thresholds.

California↗
USGS2016

Bathymetric survey and digital elevation model of Little Holland Tract, Sacramento-San Joaquin Delta, California

The U.S. Geological Survey conducted a bathymetric survey in Little Holland Tract, a flooded agricultural tract, in the northern Sacramento-San Joaquin Delta (the “Delta”) during the summer of 2015. The new bathymetric data were combined with existing data to generate a digital elevation model (DEM) at 1-meter resolution. Little Holland Tract (LHT) was historically diked off for agricultural uses and has been tidally inundated since an accidental levee breach in 1983. Shallow tidal regions such as LHT have the potential to improve habitat quality in the Delta. The DEM of LHT was developed to support ongoing studies of habitat quality in the area and to provide a baseline for evaluating future geomorphic change. The new data comprise 138,407 linear meters of real-time-kinematic (RTK) Global Positioning System (GPS) elevation data, including both bathymetric data collected from personal watercraft and topographic elevations collected on foot at low tide. A benchmark (LHT15_b1) was established for geodetic control of the survey. Data quality was evaluated both by comparing results among surveying platforms, which showed systematic offsets of 1.6 centimeters (cm) or less, and by error propagation, which yielded a mean vertical uncertainty of 6.7 cm. Based on the DEM and time-series measurements of water depth, the mean tidal prism of LHT was determined to be 2,826,000 cubic meters. The bathymetric data and DEM are available at http://dx.doi.org/10.5066/F7RX9954 .

California↗
USGS2011

From deposition to erosion: Spatial and temporal variability of sediment sources, storage, and transport in a small agricultural watershed

The spatial and temporal variability of sediment sources, storage, and transport were investigated in a small agricultural watershed draining the Coast Ranges and Sacramento Valley in central California. Results of field, laboratory, and historical data analysis in the Willow Slough fluvial system document changes that transformed a transport-limited depositional system to an effective erosion and transport system, despite a large sediment supply. These changes were caused by a combination of factors: (i) an increase in transport capacity, and (ii) hydrologic alteration. Alteration of the riparian zone and drainage network pattern during the past ~ 150 years included a twofold increase in straightened channel segments along with a baselevel change from excavation that increased slope, and increased sediment transport capacity by ~ 7%. Hydrologic alteration from irrigation water contributions also increased transport capacity, by extending the period with potential for sediment transport and erosion by ~ 6 months/year. Field measurements document Quaternary Alluvium as a modern source of fine sediment with grain size distributions characterized by 5 to 40% fine material. About 60% of an upland and 30% of a lowland study reach incised into this deposit exhibit bank erosion. During this study, the wet 2006 and relatively dry 2007 water years exhibited a range of total annual suspended sediment load spanning two orders of magnitude: ~ 108,500 kg/km 2 /year during 2006 and 5,950 kg/km 2 /year during 2007, only 5% of that during the previous year. Regional implications of this work are illustrated by the potential for a small tributary such as Willow Slough to contribute sediment – whereas large dams limit sediment supply from larger tributaries – to the Sacramento River and San Francisco Bay Delta and Estuary. This work is relevant to lowland agricultural river–floodplain systems globally in efforts to restore aquatic and riparian functions and where water quality management includes reducing fine sediment contributions that can couple with other pollutants.

California↗
USGS2010

A summary of information on the rust Puccinia psidii Winter (guava rust) with emphasis on means to prevent introduction of additional strains to Hawaii

The neotropical rust fungus Puccinia psidii ( P. psidii ) was originally described from the host common guava in its native Brazil but has been found since on hosts throughout the myrtle family (Myrtaceae), including a dramatic host jump to nonnative Eucalyptus plantations. Most rust fungi are able to live only on a very narrow range of host species. P. psidii is unusual both for having a broad host range and for the intensity of its damage to susceptible young growth. This rust first got a foothold in the United States in Florida more than three decades ago. The U.S. Department of Agriculture (USDA) has since considered it a nonactionable, nonreportable pest. Hawaii and Florida are the only two states with native species in the myrtle family. Over a period of 30 years, this rust has done little damage to any of the scattered native Myrtaceae in Florida, although the host range of the rust has gradually grown to about 30 mostly nonnative species in the family, apparently because of increasing genetic variety of the rust by repeated introductions. However, Florida’s native Myrtaceae are among the roughly 1,100 neotropical species that are largely resistant to P. psidii . The 3,000 species of non-neotropical Myrtaceae of the Pacific, Australia, Asia, and Africa are expected to prove much more vulnerable to P. psidii . Little is known about the genetics or genetic strains of P. psidii , although existing literature shows that there are numerous strains that have differential ability to infect suites of host plants. The rust was first recorded in the state of Hawaii on Oahu in April 2005 and quickly spread throughout the Hawaiian Islands. The main concern in Hawaii became the potential threat to ohia, Metrosideros polymorpha (Myrtaceae), the endemic forest tree species overwhelmingly important in Hawaii’s nature and culture. The potential ecological consequences of a virulent strain of rust on ohia forests are immense, due to its role as a foundation tree species and the diversity of niches it fills in Hawaii. A single genetic strain of the rust is established in Hawaii, apparently composed of a single genotype lacking sexual reproduction. P. psidii has been found statewide in Hawaii attacking Myrtaceae from near sea level to about 1,200 m elevation in areas with rainfall ranging from 750–5,000 mm. Five of eight native Myrtaceae and at least 15 nonnative species have been observed as hosts of P. psidii in Hawaii. The federally endangered Eugenia koolauensis (nioi) and the nonendangered indigenous species Eugenia reinwardtiana are severely damaged. The introduced (an Asian species) and invasive rose apple, Syzygium jambos , is severely affected at a landscape scale, with widespread crown dieback and many instances of complete tree death. In spite of billions of wind-dispersed rust spores produced from rose apple infestations during 2006 to 2008, adjacent ohia have been little affected to date by the rust strain in Hawaii. Within the elevation range of the rust, P. psidii is found on less than 5 percent of the ohia trees in the wild; on those ohia trees on which the rust is found, it is normally found on less than 5 percent of the leaves. The strain in Hawaii has not attacked many of the species known to be infected by the rust elsewhere, including common guava. On the basis of the very substantial genetic diversity of the much-studied, crop-damaging species of the genus Puccinia , there is good reason to believe that there are at minimum dozens and likely hundreds or thousands of genotypes of P. psidii , likely concentrated in the core range in Brazil but with potential for dispersal by globalization. Multiple genotypes are believed already present in the United States and certain to spread freely in the absence of restrictions. The U.S. Forest Service has initiated a major collaborative project in Brazil to investigate the genetics of susceptibility of Hawaii’s ohia to P. psidii , but initial results will likely not be available for several years. If just one more strain reaches Hawaii, the consequences could be dire for ohia, with each new genotype arriving having an unknown likelihood of increasing damage to ohia; possibilities for mutation and (or) genetic mixing, even with asexual strains, are apparently substantial, based on what is known about other Puccinia species. Investigations are needed to clarify rust-nioi relationships. However, it is likely that keeping out new strains of P. psidii may be important for long-term survival of nioi as well as for the health of ohia forest. The source of Hawaii’s initial invasion by P. psidii is uncertain but is strongly suspected to have been decorative foliage of species in the myrtle family from the mainland United States, most likely California, where there had been outbreaks of this rust on cultivated myrtle in 2005. In 2006–7, Maui’s Hawaii Department of Agriculture (HDOA) inspectors intercepted several P. psidii infected shipments of foliage myrtle, shipped from several California counties. Recognizing the huge threat of the rust to Hawaii’s one million acres of ohia forests, and consequently to Hawaii’s watersheds and biodiversity, Hawaii’s Board of Agriculture unanimously approved an interim rule in August 2007 banning importation of plants in the myrtle family from “infested areas,” specified as South America, Florida, and California. However, the interim rule has not been made permanent by HDOA, and the department has stated that it needs further information to formulate a long-term rule that imposes appropriate measures. Rust spores can survive for 2 to 3 months, and the pathogen can be transported to Hawaii on Myrtaceae from anywhere in the world through the United States mainland. There is much geographic reshuffling of flowers and foliage among the far-flung firms in the trade, especially for bouquet making. Because P. psidii is a nonactionable and nonreportable pest in the United States, foliage and flowers of the myrtle family can move freely into the country (usually but not necessarily always through the ports of Miami or Los Angeles), and from state to state. Currently, the State of Hawaii regulates incoming plant material in the family Myrtaceae by visual inspection. Inspection capacity and latent (asymptomatic) infections limit the ability to detect the rust. New molecular tests could improve detection efficiency, but the cost and the time required to process samples currently precludes their routine use in ports of entry. Interdiction, which has effectively kept coffee rust ( Hemileia vastatrix ) out of Hawaii for 120 years, offers the strongest protection for Hawaii’s native ecosystems from P. psidii . Interdiction of Myrtaceae from the continental United States could have the important supplementary benefit of preventing establishment in Hawaii of other very significant pests of multiple species of Myrtaceae that are already in the country, including: the Eugenia psyllid Trioza eugeniae (Hemiptera: Psyllidae); Chrysophtharta m-fuscum , the Eucalyptus tortoise beetle (Coleoptera: Chrysomelidae); Leptocybe invasa , the blue gum chalcid wasp (Hymenoptera: Chalcidae); and the fungal pathogens Mycosphaerella molleriana (Ascomycota: Mycosphaerelliaceae, crinkle leaf disease of Eucalyptus spp.) and Neofusicoccum parvum (Ascomycota: Botryosphaeriaceae), currently causing serious damage to Syzygium paniculatum in south Florida nurseries. Each of these pests would be likely to cause very significant damage to native and (or) cultivated Myrtaceae in Hawaii. Each of these pests is a prime candidate for transport by the foliage and (or) nursery stock pathways from Florida and California into Hawaii. Hawaii Department of Agriculture has a clear mandate to protect Hawaii’s natural environment, forestry and cultivated Myrtaceae. Principles of the World Trade Organization’s Treaty on Sanitary and Phytosanitary Measures and the International Plant Protection Convention are consistent with the right of Hawaii to take action. The current threat of P. psidii and the other five serious threats to Myrtaceae are primarily posed by the importation of infected plants from the continental United States; however, that may change in the future. If Hawaii were to decide to take a stand (through State regulation) to protect its native and introduced Myrtaceae, there is a possibility that USDA would consider Federal regulation of Myrtaceae from foreign countries.

Hawaii↗
USGS2003

Geohydrologic Framework of Recharge and Seawater Intrusion in the Pajaro Valley, Santa Cruz and Monterey Counties, California

Pajaro Valley is a coastal watershed of 160 square miles located along Monterey Bay north of Elkhorn Slough and south of the city of Santa Cruz. The valley has been predominantly developed for agriculture since the late 1800s. In 1984 the Pajaro Valley Water Management Agency (PVWMA) was formed and was delegated with the responsibility of the management of the water resources within the Pajaro Valley by the State of California. About 84 percent of the water is used for agriculture and 16 percent is used for industrial and municipal water supply; almost all of the demand is supplied by ground water. Ground-water pumpage varies with seasonal and climatic periods. The alluvial aquifers are composed of Quaternary- and Tertiary-aged sediments that are layered marine and terrestrial coarse-grained deposits separated by extensive fine-grained deposits that potentially restrict vertical movement of ground water and seawater intrusion in the coastal subareas. The coarse-grained deposits, which persist over large areas, control pumpage and related seawater intrusion. The Aromas Sand crops out throughout the north and central parts of the PVWMA area and offshore on the continental shelf and in Monterey submarine canyon. Because many of the wells in the coastal and inland subregions are screened at depths of 200 to 400 feet below land surface, a direct avenue is provided for seawater intrusion through the coarse-grained deposits of the shallower alluvium and Aromas Sand. Geophysical logs from monitoring wells indicate discrete zones of saline water that are related to pumpage and seawater intrusion in the aquifers of the shallower alluvium and upper Aromas Sand in the upper-aquifer system and to deeper saline waters in the lower Aromas Sand within the lower-aquifer system. The precipitation data indicate that there were at least nine dry and nine wet periods that range from 2 to 19 years during the period of record, 1880?1997. The ground-water pumpage, runoff, streamflow and related water quality of streamflow also vary with seasonal and climatic periods. Recharge occurs from deep percolation of precipitation and from infiltration of streamflow. Streamflow originates from local runoff and from outside the valley as inflow from the Pajaro River. Although partly regulated, streamflow in the Pajaro River at Chittenden is less than 200 cubic feet per second 88 percent of the time and is less than 12 cubic feet per second 50 percent of the time. Streamflow water-quality data suggest that there may be several sources of poor-quality water that contribute to elevated chloride, sulfate, and nitrate concentrations in streamflow. The poor water quality occurring during lower streamflows indicates that low flows may be an additional source of salinity for ground-water recharge as streamflow infiltration along the Pajaro River. The geochemical data from this study indicate that the two main sources of recharge are deep percolation of local runoff and streamflow infiltration of Pajaro River water. The geophysical and geochemical data suggest that only the shallow alluvial aquifer and parts of the upper Aromas Sand that constitute the upper-aquifer system are being replenished by recent recharge in the coastal areas of Pajaro Valley and represent the renewable ground-water resources. These data also suggest that there is very little vertical flow through the layered aquifer systems in the coastal regions. The confining aquitards are laterally extensive but may be missing in places owing to fluvial erosion or offsetting by fault movement. Geochemical and geophysical data indicate that the ground water from some parts of the upper and lower Aromas Sand in the coastal regions was recharged thousands of years ago and may, in part, represent nonrenewable ground-water resources. The analysis of major-ion chemistry, in combination with isotope and trace-element/chloride ratios, indicates that the coastal ground-water and surface-water samples

Water-Resources Investigations Report↗
USGS2007

Temporal trends in concentrations of DBCP and nitrate in groundwater in the eastern San Joaquin Valley, California, USA

Temporal monitoring of the pesticide 1,2-dibromo-3-chloropropane (DBCP) and nitrate and indicators of mean groundwater age were used to evaluate the transport and fate of agricultural chemicals in groundwater and to predict the long-term effects in the regional aquifer system in the eastern San Joaquin Valley, California. Twenty monitoring wells were installed on a transect along an approximate groundwater flow path. Concentrations of DBCP and nitrate in the wells were compared to concentrations in regional areal monitoring networks. DBCP persists at concentrations above the US Environmental Protection Agency's maximum contaminant level (MCL) at depths of nearly 40 m below the water table, more than 25 years after it was banned. Nitrate concentrations above the MCL reached depths of more than 20 m below the water table. Because of the intensive pumping and irrigation recharge, vertical flow paths are dominant. High concentrations (above MCLs) in the shallow part of the regional aquifer system will likely move deeper in the system, affecting both domestic and public-supply wells. The large fraction of old water (unaffected by agricultural chemicals) in deep monitoring wells suggests that it could take decades for concentrations to reach MCLs in deep, long-screened public-supply wells, however. ?? Springer-Verlag 2007.

Hydrogeology Journal↗
USGS2022

New generation hyperspectral sensors DESIS and PRISMA provide improved agricultural crop classifications

Using new remote sensing technology to study agricultural crops will support advances in food and water security. The recently launched, new generation spaceborne hyperspectral sensors, German DLR Earth Sensing Imaging Spectrometer (DESIS) and Italian PRecursore IperSpettrale della Missione Applicativa (PRISMA), provide unprecedented data in hundreds of narrow spectral bands for the study of the Earth. Therefore, our overarching goal in this study was to use these data to explore advances that can be made in agricultural research. We selected PRISMA and DESIS images during the 2020 growing season in California's Central Valley to study seven major crops. PRISMA and DESIS images were highly correlated (R 2of 0.9–0.95). Out of the 235 DESIS bands (400–1000 nm) and 238 PRISMA bands (400–2500 nm), 26 (11%) and 45 (19%) bands, respectively, were optimal to study agricultural crops. These optimal bands provided crop type classification accuracies of 83–90%. Hyperspectral vegetation indices to estimate plant pigment content, stress, biomass, moisture, and cellulose/lignin content were also identified.

California↗
USGS2021

Integrated hydrology and operations modeling to evaluate climate change impacts in an agricultural valley irrigated with snowmelt runoff

Applying models to developed agricultural regions remains a difficult problem because there are no existing modeling codes that represent both the complex physics of the hydrology and anthropogenic manipulations to water distribution and consumption. We apply an integrated groundwater – surface water and hydrologic river operations model to an irrigated river valley in northwestern Nevada/northern California, United States to evaluate the impacts of climate change on snow-fed agricultural systems that use surface water and groundwater conjunctively. We explicitly represent individual surface water rights within the hydrologic model and allow the integrated code to change river diversions in response to earlier snowmelt runoff and water availability. Historically under-used supplemental groundwater rights are dynamically activated within the model to offset diminished surface water deliveries. The model accounts for feedbacks between the natural hydrology and anthropogenic stresses, which is a first-of-its-kind assessment of the impacts of climate change on individual water rights, and more broadly on river basin operations. Earlier snowmelt decreases annual surface water deliveries to all water rights, not just the junior water rights, owing to a lack of surface water storage in the upper river basin capable of capturing earlier runoff. Conversely, downstream irrigators with access to reservoir storage benefit from earlier runoff flowing past upstream points of diversion prior to the start of the irrigation season. Despite regional shifts toward greater reliance on groundwater for irrigation, crop consumption (a common surrogate for crop yield) decreases due to spatiotemporal changes in water supply that preferentially impact a subset of growers in the region.

California↗
USGS2013

Recent land-use/land-cover change in the Central California Valley

Open access to Landsat satellite data has enabled annual analyses of modern land-use and land-cover change (LULCC) for the Central California Valley ecoregion between 2005 and 2010. Our annual LULCC estimates capture landscape-level responses to water policy changes, climate, and economic instability. From 2005 to 2010, agriculture in the region fluctuated along with regulatory-driven changes in water allocation as well as persistent drought conditions. Grasslands and shrublands declined, while developed lands increased in former agricultural and grassland/shrublands. Development rates stagnated in 2007, coinciding with the onset of the historic foreclosure crisis in California and the global economic downturn. We utilized annual LULCC estimates to generate interval-based LULCC estimates (2000–2005 and 2005–2010) and extend existing 27 year interval-based land change monitoring through 2010. Resulting change data provides insights into the drivers of landscape change in the Central California Valley ecoregion and represents the first, continuous, 37 year mapping effort of its kind.

California↗
USGS2024

Per- and polyfluoroalkyl substances (PFAS) in drinking water in Southeast Los Angeles: Industrial legacy and environmental justice

Per - and polyfluoroalkyl substances (PFAS) are persistent chemicals of increasing concern to human health. PFAS contamination in water systems has been linked to a variety of sources including hydrocarbon fire suppression activities, industrial and military land uses, agricultural applications of biosolids, and consumer products. To assess PFAS in California tap water, we collected 60 water samples from inside homes in four different geographic regions, both urban and rural. We selected mostly small water systems with known history of industrial chemical or pesticide contamination and that served socioeconomically disadvantaged communities. Thirty percent of the tap water samples (18) had a detection of at least one of the 32 targeted PFAS and most detections (89 %) occurred in heavily industrialized Southeast Los Angeles (SELA). The residents of SELA are predominately Latino and low-income. Concentrations of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) ranged from 6.8 to 13.6 ng/L and 9.4–17.8 ng/L, respectively in SELA and were higher than State (PFOA: 0.007 ng/L; PFOS: 1.0 ng/L) and national health-based goals (zero). To look for geographic patterns, we mapped potential sources of PFAS contamination, such as chrome plating facilities, airports, landfills, and refineries, located near the SELA water systems; consistent with the multiple potential sources in the area, no clear spatial associations were observed. The results indicate the importance of systematic testing of PFAS in tap water, continued development of PFAS regulatory standards and advisories for a greater number of compounds, improved drinking-water treatments to mitigate potential health threats to communities, especially in socioeconomically disadvantaged and industrialized areas.

California↗
USGS2012

Planned updates and refinements to the Central Valley hydrologic model with an emphasis on improving the simulation of land subsidence in the San Joaquin Valley

California's Central Valley has been one of the most productive agricultural regions in the world for more than 50 years. To better understand the groundwater availability in the valley, the U.S. Geological Survey (USGS) developed the Central Valley hydrologic model (CVHM). Because of recent water-level declines and renewed subsidence, the CVHM is being updated to better simulate the geohydrologic system. The CVHM updates and refinements can be grouped into two general categories: (1) model code changes and (2) data updates. The CVHM updates and refinements will require that the model be recalibrated. The updated CVHM will provide a detailed transient analysis of changes in groundwater availability and flow paths in relation to climatic variability, urbanization, stream flow, and changes in irrigated agricultural practices and crops. The updated CVHM is particularly focused on more accurately simulating the locations and magnitudes of land subsidence. The intent of the updated CVHM is to help scientists better understand the availability and sustainability of water resources and the interaction of groundwater levels with land subsidence.

California↗
USGS1990

Concentrations of boron, molybdenum, and selenium in chinook salmon

The concentrations of boron, molybdenum, and selenium in young chinook salmon Oncorhynchus tshawytscha were determined in three partial life cycle chronic toxicity studies. In each study, fish were exposed to a mixture of boron, molybdenum, selenate, and selenite in the proportions found in subsurface agricultural drainage water in the basin of the San Joaquin Valley, California. Tests were conducted in well water and in site-specific fresh and brackish waters. No boron or molybdenum was detected in fish exposed to concentrations as high as 6,046 μg boron/L and 193 μg molybdenum/L for 90 d in well water or fresh water; however, whole-body concentrations of selenium increased with increasing exposure concentrations in well water and fresh water, but not in brackish water. Concentrations of selenium in chinook salmon were strongly correlated with reduced survival and growth of fish in well water and with reduced survival in a 15-d seawater challenge test of fish from fresh water. Concentrations of selenium in fish seemed to reach a steady state after 60 d of exposure in well water or fresh water. Fish in brackish water had only background concentrations of selenium after 60 d of exposure, and no effects on survival and growth in brackish water or on survival in a 10-d seawater challenge test were exhibited. This lack of effect in brackish water was attributed to initiation of the study with advanced fry, which were apparently better able to metabolize the trace element mixture than were the younger fish used in studies with well water and fresh water. In all three experimental waters, concentration factors (whole-body concentration/waterborne concentration) for selenium decreased with increasing exposure concentrations, suggesting decreased uptake or increased excretion, or both, of selenium at the higher concentrations.

Transactions of the American Fisheries Society↗
USGS2009

The relative importance of disturbance and exotic-plant abundance in California coastal sage scrub

Many ecosystems of conservation concern require some level of disturbance to sustain their species composition and ecological function. However, inappropriate disturbance regimes could favor invasion or expansion of exotic species. In southern California coastal sage scrub (CSS) fire is a natural disturbance, but because of human influence, frequencies may now be unnaturally high. Other anthropogenic disturbances such as grazing also occur in reserve areas. Managers charged with imposing or tolerating fire or other disturbance within their reserves are concerned that habitat quality may be degraded by an increasing abundance of exotic plants. We used vegetation monitoring data from Camp Pendleton, California, USA, to assess the correlation between past disturbances (frequent fire, agriculture, or grazing and mechanical disturbances) and current exotic species abundance in CSS. We found that disturbance history was only modestly related to exotic abundance overall, but fire frequency showed the strongest association. We also examined whether cover and richness of various native plant life forms (woody species, perennial herbs, and annual herbs) were more strongly influenced by disturbance history or by exotic-plant abundance. Native plant responses varied among life forms, but woody species and annual herbs were generally more strongly and negatively associated with exotic abundance than with disturbance. Effective CSS conservation will require developing means to curb the negative impacts of exotic plants, which may abound with or without severe or recent disturbance. Additionally, more focus should be given to understory herbs showing sensitivity to invasion. Though understudied, native herbs comprise the greatest portion of plant diversity in CSS and are critical to preservation of the community as a whole. ?? 2009 by the Ecological Society of America.

Ecological Applications↗
USGS2008

Regional nitrate and pesticide trends in ground water in the eastern San Joaquin Valley, California

Protection of ground water for present and future use requires monitoring and understanding of the mechanisms controlling long-term quality of ground water. In this study, spatial and temporal trends in concentrations of nitrate and pesticides in ground water in the eastern San Joaquin Valley, California, were evaluated to determine the long-term effects of agricultural and urban development on regional ground-water quality. Trends in concentrations of nitrate, the nematocide 1,2-dibromo-3-chloropropane, and the herbicide simazine during the last two decades are generally consistent with known nitrogen fertilizer and pesticide use and with the position of the well networks in the regional ground-water flow system. Concentrations of nitrate and pesticides are higher in the shallow part of the aquifer system where domestic wells are typically screened, whereas concentrations are lower in the deep part of the aquifer system where public-supply wells are typically screened. Attenuation processes do not seem to significantly affect concentrations. Historical data indicate that concentrations of nitrate have increased since the 1950s in the shallow and deep parts of the aquifer system. Concentrations of nitrate and detection of pesticides in the deep part of the aquifer system will likely increase as the proportion of highly affected water contributed to these wells increases with time. Because of the time of travel between the water table and the deep part of the aquifer system, current concentrations in public-supply wells likely reflect the effects of 40- to 50-yr-old management practices. Copyright ?? 2008 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.

Conference Paper↗