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At least 271 records · Page 15Linked to original sources
USGS1983

Problems in estimating self-supplied industrial water use by indirect methods, the California example

Consumptive fresh-water use by industry in California is estimated at about 230 million gallons per day, or about one-half of one percent of agricultural withdrawals in the State , and only about 1 percent of agricultural consumptive use. Therefore, a significant State-wide realignment of the total water resources could not be made by industrial conservation measures. Nevertheless, considerable latitude for water conservation exists in industry -- fresh water consumed by self-supplied industry amounts to about 40 percent of its withdrawals in California, and only about 10 to 15 percent nationally (not including power-plant use). Furthermore, where firms withdraw and consume less water there is more for others nearby to use. The main question in attempting to estimate self-supplied industrial water use in California by indirect methods was whether accurate estimates of industrial water use could be made from data on surrogates such as production and employment. The answer is apparently not. A fundamental problem was that different data bases produced variable coefficients of water use for similar industries. Much of the potential for error appeared to lie in the water data bases rather than the production or employment data. The apparent reasons are that water-use data are based on responses to questionnaires, which are prone to errors in reporting, and because the data may be aggregated inappropriately for this kind of correlation. Industries within an apparently similar category commonly use different amounts of water, both because of differences in the product and because of differences in production processes even where the end-product is similar. (USGS)

Water-Resources Investigations Report↗
USGS1995

Inputs of the Dormant-Spray Pesticide, Diazinon, to the San Joaquin River, California, February 1993

INTRODUCTION The objective of the National Water Quality Assessment (NAWQA) Program of the U.S. Geological Survey is to describe the status and trends of the Nation's water quality with respect to natural features of the environment and human activities or land-use. Pesticides are a major water-quality issue in the San Joaquin Valley of California (fig. 1), and pesticide residues may be transported to rivers and streams in agricultural runoff following winter storms. Three sites in the western San Joaquin Valley were monitored during and after two February 1993 storms. The storms occurred after extensive spraying of organophosphate insecticides, mostly diazinon, on almond and other stone-fruit orchards.

Fact Sheet↗
USGS1977

Evaluation of ground-water quality in the Santa Maria Valley, California

The quality and quantity of recharge to the Santa Maria Valley groundwater basin from natural sources, point sources, and agriculture were evaluated. The results are expressed in terms of a hydrologic budget, a solute balance, and maps showing the distribution of selected chemical constituents in ground water. Point sources of waste discharge that could cause ground-water degradation were investigated including a sugar-beet refinery, oil refineries and oil-field wastewater, stockyards, golf courses, poultry farms, solid-waste landfills, and municipal and industrial wastewater-treatment facilities. Measurements of specific conductance of ground water and water levels in nearly 400 wells and the analyses of about 100 water samples for most major anions and cations plus detergents, dissolved organic carbon, and trace metals permitted preparation of maps showing the potentiometric surface and the distribution of dissolved solids, chloride, sulfate, calcium plus magnesium, and nitrogen in ground water. Pumpage of ground water for agricultural, municipal, and industrial uses has exceeded recharge by about 10,000 acre-feet per year (12.3 cubic hectometers per year). Most of the ground water pumped in the Santa Maria Valley is for agriculture. The result of pumping in excess of recharge is a declining potentiometric surface, an accumulation of solutes, and an increase in nitrogen in ground water. At present (1976), the area of confined water is most severely affected by this degradation. Nitrogen concentrations in ground water have reached as much as 50 milligrams per liter in isolated areas, with concentrations in excess of 10 milligrams per liter occurring through most of the area of confined water. Continued pumping in excess of recharge may also lower the potentiometric surface sufficiently to permit intrusion of seawater into the fresh-water zones. Discharge of wastewater from municipal and industrial wastewater-treatment facilities is also contributing solutes to the ground-water system. In comparison to the influences of irrigation return water on ground-water quality, the contribution from point sources is less than 10 percent of the total solutes. In some areas of the valley, the concentration of dissolved solids and some chemical constituents in water discharging from municipal and industrial wastewater-treatment facilities is lower than in the receiving ground water.

California↗
USGS1983

Evaluation of the San Dieguito, San Elijo, and San Pasqual hydrologic subareas for reclaimed water use, San Diego County, California

A study was made to determine the suitability of three small hydrologic subareas in San Diego County, California, for reuse of municipal wastewater. Ground-water quality has been impacted by agricultural water use, imported water use, changes in natural recharge patterns, seawater intrusion, and intrusion of ground water from surrounding marine sediments; therefore, ground water is of limited value as a water-supply source. Reclaimed water use is feasible and expected to improve ground-water quality, creating a new source of water for agricultural use.

Calilfornia↗
USGS2005

Evaluating water management strategies with the Systems Impact Assessment Model: SIAM version 4

Water from many of California's coastal rivers has been used for a wide variety of development ventures, including major agricultural diversions, hydropower generation, and contaminant assimilation from industry, agriculture and logging. Anthropogenic impacts often degrade water quality and decrease the quantity and quality of aquatic habitat. Reallocating streamflow away from uses that degrade water quality to uses that foster higher water quality is a critical step in restoring riverine habitat and the anadromous fish that rely on that habitat for a portion of their life cycle. Reallocation always brings with it the need to examine the economic efficiency of the proposed changes. If the dollar benefits of improving water quality are greater than the costs, the criterion of improving economic efficiency is satisfied, a fact that can be highly persuasive to decision makers contemplating reallocation. Previous related studies have examined nonmarket benefits of the Trinity River in northern California (Douglas and Taylor, 1998; Douglas and Taylor, 1999abc) but nothing of this kind had been done on the Klamath River, another system with numerous uses for and competition over water in times of drought. An economic survey is nearing completion for the mid- to lower Klamath River, including the Scott, Shasta, and Salmon Rivers, but excluding the Trinity River. This survey provides valuable insights about the magnitude of the benefits and nature of the costs of reallocating water from market uses to instream flows that improve water quality and assist in the recovery of Klamath River fish stocks. Preliminary survey results (Douglas and Johnson, 2002; Douglas and Sleeper, In Prep.) indicate that about 234,000 California, Oregon, and Nevada households made recreation trips to the Klamath River Basin 1997-1998 and that these users spent about $372 million on trip related expenditures. Clearly the prosperity of the region is closely linked to the demand for mid- and lower Klamath River Basin recreation trips. Further, respondents indicated that they would make roughly 36% more recreational trips per annum to the Klamath if the water quality and the fishery were restored to an unspoiled condition. Using two distinct types of survey data, these additional trips would yield benefits with a present value of approximately $9.6 billion (at a discount rate of 7.5%). Calculating costs to restore the fishery and raise water quality involved five major hypothetical restoration activities: (1) purchasing Klamath project farmland and environmentally sensitive forest lands, (2) allocating more water down the Trinity River to enhance the quantity and quality of Klamath flows below the confluence, (3) removing four mainstem dams along the Klamath River and losing their associated hydropower production, (4) eliminating all harvest of Klamath-Trinity fish stocks for a 12-year period including the acquisition of fishing rights from both tribal and commercial marine fishermen, and (5) operating all Klamath-Trinity fish hatcheries to restore self-reproducing stocks. In total, restoration costs were estimated to be about $1.7 to $2.3 billion. If the assumptions used in this study are valid, it is clear that the benefits ($9.6B) outweigh the costs of restoring water quality and the fishery. The apparent disparity between restoration benefits and costs for the Klamath River may suggest to some that water resources on the Klamath be reallocated to environmentally friendly nonmarket uses. The economic analysis rests in part on the information made available to the survey designers by the biological, hydrologic, and water quality data incorporated in The System Impact Assessment Model (SIAM). It is our hope that SIAM can be used to improve the river's water quality and fishery, and strengthen the important regional economy.

Open-File Report↗
USGS2014

Mercury cycling in agricultural and managed wetlands: a synthesis of methylmercury production, hydrologic export, and bioaccumulation from an integrated field study

With seasonal wetting and drying, and high biological productivity, agricultural wetlands (rice paddies) may enhance the conversion of inorganic mercury (Hg(II)) to methylmercury (MeHg), the more toxic, organic form that biomagnifies through food webs. Yet, the net balance of MeHg sources and sinks in seasonal wetland environments is poorly understood because it requires an annual, integrated assessment across biota, sediment, and water components. We examined a suite of wetlands managed for rice crops or wildlife during 2007–2008 in California's Central Valley, in an area affected by Hg contamination from historic mining practices. Hydrologic management of agricultural wetlands for rice, wild rice, or fallowed — drying for field preparation and harvest, and flooding for crop growth and post-harvest rice straw decay — led to pronounced seasonality in sediment and aqueous MeHg concentrations that were up to 95-fold higher than those measured concurrently in adjacent, non-agricultural permanently-flooded and seasonally-flooded wetlands. Flooding promoted microbial MeHg production in surface sediment of all wetlands, but extended water residence time appeared to preferentially enhance MeHg degradation and storage. When incoming MeHg loads were elevated, individual fields often served as a MeHg sink, rather than a source. Slow, horizontal flow of shallow water in the agricultural wetlands led to increased importance of vertical hydrologic fluxes, including evapoconcentration of surface water MeHg and transpiration-driven advection into the root zone, promoting temporary soil storage of MeHg. Although this hydrology limited MeHg export from wetlands, it also increased MeHg exposure to resident fish via greater in situ aqueous MeHg concentrations. Our results suggest that the combined traits of agricultural wetlands — slow-moving shallow water, manipulated flooding and drying, abundant labile plant matter, and management for wildlife — may enhance microbial methylation of Hg(II) and MeHg exposure to local biota, as well as export to downstream habitats during uncontrolled winter-flow events.

California↗
USGS2018

Ground-nesting great horned owl in Suisun Marsh, California

Great horned owls (Bubo virginianus) are widespread throughout North, Central, and parts of South America (Artuso et al. 2013). Across this range, great horned owls are generalists, occupying a diverse range of habitats including deciduous and coniferous forests, wetlands, and agricultural landscapes. Within these habitats, great horned owls are generally found near upland or short-vegetation habitat suitable for locating prey (Artuso et al. 2013). In Suisun Marsh, California, great horned owls primarily occupy stands of non-native eucalyptus (Eucalyptus spp.), as well as man-made structures like waterfowl-nesting platforms (Figure 1) and on dock pilings over water (Figure 2), and they forage in nearby upland fields and seasonally flooded, diked wetlands managed primarily for waterfowl (USGS unpublished data).

California↗
USGS2012

Climate change and climate systems influence and control the atmospheric dispersion of desert dust: implications for human health

The global dispersion of desert dust through Earth’s atmosphere is greatly influenced by temperature. Temporal analyses of ice core data have demonstrated that enhanced dust dispersion occurs during glacial events. This is due to an increase in ice cover, which results in an increase in drier terrestrial cover. A shorter temporal analysis of dust dispersion data over the last 40 years has demonstrated an increase in dust transport. Climate systems or events such as the North Atlantic Oscillation, the Indian Ocean subtropical High, Pacific Decadal Oscillation, and El Nino-Sothern Oscillation are known to influence global short-term dust dispersion occurrence and transport routes. Anthropogenic influences on dust transport include deforestation, harmful use of topsoil for agriculture as observed during the American Dust Bowl period, and the creation of dry seas (Aral Sea) and lakes (Lake Owens in California and Lake Chad in North Africa) through the diversion of source waters (for irrigation and drinking water supplies). Constituents of desert dust both from source regions (pathogenic microorganisms, organic and inorganic toxins) and those scavenged through atmospheric transport (i.e., industrial and agricultural emissions) are known to directly impact human and ecosystem health. This presentation will present a review of global scale dust storms and how these events can be both a detriment and benefit to various organisms in downwind environments.

Conference Paper↗
USGS2016

Increased body mass of ducks wintering in California's Central Valley

Waterfowl managers lack the information needed to fully evaluate the biological effects of their habitat conservation programs. We studied body condition of dabbling ducks shot by hunters at public hunting areas throughout the Central Valley of California during 2006–2008 compared with condition of ducks from 1979 to 1993. These time periods coincide with habitat increases due to Central Valley Joint Venture conservation programs and changing agricultural practices; we modeled to ascertain whether body condition differed among waterfowl during these periods. Three dataset comparisons indicate that dabbling duck body mass was greater in 2006–2008 than earlier years and the increase was greater in the Sacramento Valley and Suisun Marsh than in the San Joaquin Valley, differed among species (mallard [ Anas platyrhynchos ], northern pintail [ Anas acuta ], America wigeon [ Anas americana ], green-winged teal [ Anas crecca ], and northern shoveler [ Anas clypeata ]), and was greater in ducks harvested late in the season. Change in body mass also varied by age–sex cohort and month for all 5 species and by September–January rainfall for all except green-winged teal. The random effect of year nested in period, and sometimes interacting with other factors, improved models in many cases. Results indicate that improved habitat conditions in the Central Valley have resulted in increased winter body mass of dabbling ducks, especially those that feed primarily on seeds, and this increase was greater in regions where area of post-harvest flooding of rice and other crops, and wetland area, has increased. Conservation programs that continue to promote post-harvest flooding and other agricultural practices that benefit wintering waterfowl and continue to restore and conserve wetlands would likely help maintain body condition of wintering dabbling ducks in the Central Valley of California.

California↗
USGS2008

A mass balance mercury budget for a mine-dominated lake: Clear Lake, California

The Sulphur Bank Mercury Mine (SBMM), active intermittently from 1873–1957 and now a USEPA Superfund site, was previously estimated to have contributed at least 100 metric tons (10 5 kg) of mercury (Hg) into the Clear Lake aquatic ecosystem. We have confirmed this minimum estimate. To better quantify the contribution of the mine in relation to other sources of Hg loading into Clear Lake and provide data that might help reduce that loading, we analyzed Inputs and Outputs of Hg to Clear Lake and Storage of Hg in lakebed sediments using a mass balance approach. We evaluated Inputs from (1) wet and dry atmospheric deposition from both global/regional and local sources, (2) watershed tributaries, (3) groundwater inflows, (4) lakebed springs and (5) the mine. Outputs were quantified from (1) efflux (volatilization) of Hg from the lake surface to the atmosphere, (2) municipal and agricultural water diversions, (3) losses from out-flowing drainage of Cache Creek that feeds into the California Central Valley and (4) biotic Hg removal by humans and wildlife. Storage estimates include (1) sediment burial from historic and prehistoric periods (over the past 150–3,000 years) from sediment cores to ca. 2.5m depth dated using dichloro diphenyl dichloroethane (DDD), 210 Pb and 14 C and (2) recent Hg deposition in surficial sediments. Surficial sediments collected in October 2003 (11 years after mine site remediation) indicate no reduction (but a possible increase) in sediment Hg concentrations over that time and suggest that remediation has not significantly reduced overall Hg loading to the lake. Currently, the mine is believed to contribute ca. 322–331 kg of Hg annually to Clear Lake, which represents ca. 86–99% of the total Hg loading to the lake. We estimate that natural sedimentation would cover the existing contaminated sediments within ca. 150–300 years.

Water, Air, & Soil Pollution↗
USGS1980

Potential effects of increased ground-water pumpage on Barka Slough, San Antonio Creek Valley, Santa Barbara County, California

Ground-water use in San Antonio Creek valley is expected to increase significantly as a result of planned extensive agricultural development in the basin. The effects of this additional stress on the ground-water system, particularly on the environmentally sensitive Barka, Slough, are of concern in the basin. Expectations of the developer are that about 6,640 acre-feet per year of additional consumptive ground-water use will be required to irrigate an agricultural development of 2,500 acres of vineyards and 1,200 acres of truck-farmed vegetables. This represents an increase in net basin pumpage of about 60 percent. The developer plans to obtain this water from 12 large-diameter irrigation wells in the Harris Canyon area. Analysis of the potential drawdowns in the vicinity of Barka Slough, by using the Theis nonequilibrium formula, indicates that drawdowns would average 6 feet after 10 years of pumping and would eventually exceed 10 feet. Because the artesian head in the aquifer that supplies the slough is generally less than 3 feet above land surface, these declines would probably mean that the wetlands of Barka Slough would disappear. An empirical relation, based on historical records of base flow in San Antonio Creek and net pumpage in the basin, also indicates that the additional irrigation withdrawals would cause base flow in San Antonio Creek to cease. Both of these analyses consider the effects of only this particular agricultural development, which would be in addition to any decline caused by other increases in pumpage in the basin.

California↗
USGS2026

Satellite embeddings for crop type classification: A comparative examination

Embedding datasets encode complex relationships among multiple sources of Earth observation data into a compact format. Here, we evaluated the utility of a 10-m global Satellite Embedding product (SE) for classifying crop types in central California for the year 2020. We compared the classification accuracy of a random forest model based exclusively on the SE layer to an existing random forest model with multiple imagery inputs. Our results showed the SE-based classification had higher agreement with the reference dataset (California Department of Water Resources crop map) than the classification based on Landsat and National Agricultural Imagery Program inputs (94.7% versus. 91.9% overall accuracy, respectively). The performance of individual crop types was consistent across models, ranging from high agreement for rice (98.4% versus 98% accuracy) to lower agreement for pasture, grain, and fallow/young perennial classes (< 65% accuracy in both models). The SE-based workflow used three times less cloud-based computational resources and represented substantial savings of predictor development time. Geospatial embedding products can aid classification efforts by reducing predictor development time and processing demands while maintaining classification accuracy.

California↗
USGS1985

Evaluation of the Mission, Santee, and Tijuana hydrologic subareas for reclaimed-water use, San Diego County, California

A study was made to determine the suitability of three small hydrologic subareas in San Diego County, California, for reuse of treated municipal wastewater (reclaimed water). Groundwater quality has been impacted by agricultural water use, changes in natural recharge patterns, seawater intrusion, and groundwater movement from surrounding marine sediments. Groundwater levels near land surface may limit artificial recharge of reclaimed water or may require pumping of groundwater from the aquifer prior to recharge with reclaimed water. Reclaimed water may be used for irrigated water in upland areas. (USGS)

Water-Resources Investigations Report↗
USGS2018

Construction and analysis of a giant gartersnake (Thamnophis gigas) population projection model

The giant gartersnake ( Thamnophis gigas ) is a state and federally threatened species precinctive to California. The range of the giant gartersnake has contracted in the last century because its wetland habitat has been drained for agriculture and development. As a result of this habitat alteration, giant gartersnakes now largely persist in and near rice agriculture in the Sacramento Valley, because the system of canals that conveys water for rice growing approximates historical wetland habitat. Many aspects of the demography of giant gartersnakes are unknown, including how individuals grow throughout their life, how size influences reproduction, and how survival varies over time and among populations. We studied giant gartersnakes throughout the Sacramento Valley of California from 1995 to 2016 using capture-mark-recapture to study the growth, reproduction, and survival of this threatened species. We then use these data to construct an Integral Projection Model, and analyze this demographic model to understand which vital rates contribute most to the growth rate of giant gartersnake populations. We find that giant gartersnakes exhibit indeterminate growth; growth slows as individuals’ age. Fecundity, probability of reproduction, and survival all increase with size, although survival may decline for the largest female giant gartersnakes. The population growth rate of giant gartersnakes is most influenced by the survival and growth of large adult females, and the size at which 1 year old recruits enter the population. Our results indicate that management actions benefitting these influential demographic parameters will have the greatest positive effect on giant gartersnake population growth rates, and therefore population persistence. This study informs the conservation and management of giant gartersnakes and their habitat, and illustrates the effectiveness of hierarchical Bayesian models for the study of rare and elusive species.

Open-File Report↗
USGS2018

Occurrence of Batrachochytrium dendrobatidis in anurans of the Mediterranean region of Baja California, México

Chytridiomycosis is caused by the fungal pathogen Batrachochytrium dendrobatidis ( Bd ) and is regarded as one of the most significant threats to global amphibian populations. In México, Bd was first reported in 2003 and has now been documented in 13 states. We visited 33 localities and swabbed 199 wild-caught anurans from 7 species (5 native, 2 exotic) across the Mediterranean region of the state of Baja California. Using quantitative PCR, Bd was detected in 94 individuals (47.2% of samples) at 25 of the 33 survey localities for 5 native and 1 exotic frog species. The exotic Xenopus laevis was the only species that tested completely negative for Bd . We found that remoteness, distance to agricultural land, and elevation were the best predictors of Bd presence. These are the first Bd -positive results for the state of Baja California and its presence should be regarded as an additional conservation threat to the region’s native frog species.

Baja California↗
USGS2018

Quantifying anthropogenic contributions to century-scale groundwater salinity changes, San Joaquin Valley, California, USA

Total dissolved solids (TDS) concentrations in groundwater tapped for beneficial uses (drinking water, irrigation, freshwater industrial) have increased on average by about 100 mg/L over the last 100 years in the San Joaquin Valley, California (SJV). During this period land use in the SJV changed from natural vegetation and dryland agriculture to dominantly irrigated agriculture with growing urban areas. Century-scale salinity trends were evaluated by comparing TDS concentrations and major ion compositions of groundwater from wells sampled in 1910 (Historic) to data from wells sampled in 1993-2015 (Modern). TDS concentrations in subregions of the SJV, the southern (SSJV), western (WSJV), northeastern (NESJV), and southeastern (SESJV) were calculated using a cell-declustering method. TDS concentrations increased in all regions, with the greatest increases found in the SSJV and SESJV. Evaluation of the Modern data from the NESJV and SESJV found higher TDS concentrations in recently recharged (post-1950) groundwater from shallow (< 50 m) wells surrounded predominantly by agricultural land uses, while premodern (pre-1950) groundwater from deeper wells, and recently recharged groundwater from wells surrounded by mainly urban, natural, and mixed land uses had lower TDS concentrations, approaching the TDS concentrations in the Historic groundwater. For the NESJV and SESJV, inverse geochemical modeling with PHREEQC indicated that weathering of primary silicate minerals accounted for the majority of the increase in TDS concentrations, contributing more than nitrate from fertilizers and sulfate from soil amendments combined. Bicarbonate showed the greatest increase among major ions, resulting from enhanced silicate weathering due to recharge of irrigation water enriched in CO2 during the growing season. The results of this study demonstrate that large anthropogenic changes to the hydrologic regime, like massive development of irrigated agriculture in semi-arid areas like the SJV, can cause large changes in groundwater quality on a regional scale.

California↗
USGS2015

Experimental dosing of wetlands with coagulants removes mercury from surface water and decreases mercury bioaccumulation in fish

Mercury pollution is widespread globally, and strategies for managing mercury contamination in aquatic environments are necessary. We tested whether coagulation with metal-based salts could remove mercury from wetland surface waters and decrease mercury bioaccumulation in fish. In a complete randomized block design, we constructed nine experimental wetlands in California’s Sacramento–San Joaquin Delta, stocked them with mosquitofish ( Gambusia affinis ), and then continuously applied agricultural drainage water that was either untreated (control), or treated with polyaluminum chloride or ferric sulfate coagulants. Total mercury and methylmercury concentrations in surface waters were decreased by 62% and 63% in polyaluminum chloride treated wetlands and 50% and 76% in ferric sulfate treated wetlands compared to control wetlands. Specifically, following coagulation, mercury was transferred from the filtered fraction of water into the particulate fraction of water which then settled within the wetland. Mosquitofish mercury concentrations were decreased by 35% in ferric sulfate treated wetlands compared to control wetlands. There was no reduction in mosquitofish mercury concentrations within the polyaluminum chloride treated wetlands, which may have been caused by production of bioavailable methylmercury within those wetlands. Coagulation may be an effective management strategy for reducing mercury contamination within wetlands, but further studies should explore potential effects on wetland ecosystems.

California↗