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USGS2015

Estimated annual agricultural pesticide use for counties of the conterminous United States, 2008-12

Annual county-level pesticide use was estimated for 423 herbicides, insecticides, and fungicides applied to agricultural crops grown in the conterminous United States during 2008–12. For all States except California, pesticide-use data were compiled from proprietary surveys of farm operations located within U.S. Department of Agriculture Crop Reporting Districts (CRDs). Surveyed pesticide-use data were used in conjunction with county annual harvested-crop acres reported by the U.S. Department of Agriculture 2007 and 2012 Censuses of Agriculture and the 2008–11 County Agricultural Production Survey to calculate use rates per harvested-crop acre, or an “estimated pesticide use” (EPest) rate, for each crop by year. County-use estimates were then calculated by multiplying EPest rates by harvested-crop acres for each pesticide crop combination. Use estimates for California were obtained from annual Department of Pesticide Regulation-Pesticide Use Reports. Proprietary surveyed pesticide-use data were not available for all CRDs and years. When pesticide-survey data were unavailable for a CRD in a particular year, EPest extrapolated rates were calculated from adjoining or nearby CRDs to ensure that pesticide use was estimated for all counties where harvested-crop acres were reported. Two estimation methods were used—EPest-low and EPest high—and differed in how they treated situations when a CRD was surveyed and pesticide use was not reported for a particular pesticide-by-crop combination. California pesticide-use estimates were not extrapolated; therefore, EPest-low and EPest-high are the same for counties in California. This data series is a continuation of the 1992–2009 pesticide-use estimates reported by Stone (2013). It is an update of estimates for 2008–9 (Stone, 2013), as well as an update of the 2010–11 preliminary estimates reported by Baker and Stone (2013). EPest values from these compilations (1992–2012) are suitable for making national, regional, and watershed assessments of annual pesticide use. County-level estimates are provided to make it easier to compile watershed assessments; however, users should be aware there is a greater degree of uncertainty in individual county-level estimates when compared to CRD or State-level estimates. This report provides EPest-low and EPest-high annual agricultural pesticide use for counties of the conterminous United States for 423 compounds during 2008–12 in tab-delimited files organized by compound, year, State Federal Information Processing Standard (FIPS) code, county FIPS code, and amount in kilograms (kg). EPest-high county pesticide-use estimates were divided into tables 1 through 7 by pesticide name: Table 1: 2, 4-D through Chlorantraniliprole Table 2: Chlorethoxyfos through Diflufenzopyr Table 3: Dimethenamid through Gibberellic acid Table 4: Glufosinate through Metiram Table 5: Metolachlor through Propazine Table 6: Propiconazole through Triasulfuron Table 7: Tribenuron methyl through Zoxamide EPest-low county pesticide-use estimates were divided into tables 8 through 14 by pesticide name: Table 8: 2, 4-D through Chlorantraniliprole Table 9: Chlorethoxyfos through Diflufenzopyr Table 10: Dimethenamid through Gibberellic acid Table 11: Glufosinate through Metiram Table 12: Metolachlor through Propazine Table 13: Propiconazole through Triasulfuron Table 14: Tribenuron methyl through Zoxamide

Data Series↗
USGS2010

Temporal and spatial distributions of sediment mercury at salt pond wetland restoration sites, San Francisco Bay, CA, USA

Decommissioned agricultural salt ponds within south San Francisco Bay, California, are in the process of being converted to habitat for the benefit of wildlife as well as water management needs and recreation. Little is known of baseline levels of contaminants in these ponds, particularly mercury (Hg), which has a well established legacy in the Bay. In this study we described spatial and short-term temporal variations in sediment Hg species concentrations within and among the Alviso and Eden Landing salt ponds in the southern region of San Francisco Bay. We determined total Hg (Hg t ) and methylmercury (MeHg) in the top 5 cm of sediment of most ponds in order to establish baseline conditions prior to restoration, sediment Hg t concentrations in a subset of these ponds after commencement of restoration, and variation in MeHg concentrations relative to sediment Hg t , pH, and total Fe concentrations and water depth and salinity in the subset of Alviso ponds. Inter-pond differences were greatest within the Alviso pond complex, where sediment Hg t concentrations averaged (arithmetic mean) 0.74 [mu]g/g pre and 1.03 [mu]g/g post-restoration activity compared to 0.11 [mu]g/g pre and post at Eden Landing ponds. Sediment Hg t levels at Alviso were fairly stable temporally and spatially, whereas MeHg levels were variable relative to restoration activities across time and space. Mean (arithmetic) sediment MeHg concentrations increased (2.58 to 3.03 ng/g) in Alviso and decreased (2.20 to 1.03 ng/g) in Eden Landing restoration ponds during the study. Differences in MeHg levels were related to water depth and pH, but these relationships were not consistent between years or among ponds and were viewed with caution. Factors affecting MeHg levels in these ponds (and in general) are highly complex and require in-depth study to understand.

Science of the Total Environment↗
USGS2009

The legacy of wetland drainage on the remaining peat in the Sacramento-San Joaquin Delta, California, USA

Throughout the world, many extensive wetlands, such as the Sacramento-San Joaquin Delta of California (hereafter, the Delta), have been drained for agriculture, resulting in land-surface subsidence of peat soils. The purpose of this project was to study the in situ effects of wetland drainage on the remaining peat in the Delta. Peat cores were retrieved from four drained, farmed islands and four relatively undisturbed, marsh islands. Core samples were analyzed for bulk density and percent organic carbon. Macrofossils in the peat were dated using radiocarbon age determination. The peat from the farmed islands is highly distinct from marsh island peat. Bulk density of peat from the farmed islands is generally greater than that of the marsh islands at a given organic carbon content. On the farmed islands, increased bulk density, which is an indication of compaction, decreases with depth within the unoxidized peat zone, whereas, on the marsh islands, bulk density is generally constant with depth except near the surface. Approximately 55–80% of the original peat layer on the farmed islands has been lost due to landsurface subsidence. For the center regions of the farmed islands, this translates into an estimated loss of between 2900-5700 metric tons of organic carbon/hectare. Most of the intact peat just below the currently farmed soil layer is over 4000 years old. Peat loss will continue as long as the artificial water table on the farmed islands is held below the land surface.

California↗
USGS2013

Selenium in irrigated agricultural areas of the western United States

Selenium was recognized as an important aquatic contaminant following the identification of widespread deformities in waterfowl at the agricultural drainage evaporation ponds of the Kesterson Reservoir (California) in 1983. Since then, California has been the focal point for global research and management of Se contamination. We analyzed the history and current developments in science, policy, and management of irrigation-induced Se contamination in California. In terms of management, we evaluated the effects of improvements in the design of local attenuation methods (drainage reuse and evaporation ponds) in conjunction with the development of programs for Se load reductions at the regional scale (namely the Grassland Bypass Project). In terms of policy, the USEPA is currently working on site-specific water quality criteria for the San Francisco Bay Delta that may be a landmark for future legislation on Se in natural water bodies. We provide a critical analysis of this approach and discuss challenges and opportunities in expanding it to other locations such as the Salton Sea. Management lessons learned in California and the novel policy approach may help prevent future events of Se contamination.

Journal of Environmental Quality↗
USGS1996

Well-construction, water-quality, and water-level data, and pond-infiltration estimates, for three ground-water subbasins, Riverside County, California

Reclaimed water in the Eastern Municipal Water District of Riverside County,California, is used within the service area for agricultural irrigation.Owing to the seasonal demand for reclaimed water, storage/infiltration ponds were constructed in the Winchester, Menifee, and south Perris subbasins.Reclaimed water infiltrates from these ponds and enters the groundwater system. Little is known of the effects of the reclaimed water on groundwater quality. In cooperation with the Eastern MunicipalWater District, the U.S. Geological Survey began a study in 1995 to determine the quantity and fate of reclaimed water percolating from these storage ponds. Data compiled during the first phase of this study are presented in this report. Field reconnaissance of the Winchester, Menifee, and south Perris subbasins indicated the existence of many wells. Wellconstruction data for 115 of these wells were tabulated. Available historical waterquality and waterlevel data for 178 wells in the subbasins also were tabulated. In addition, water levels in 86 wells were measured during the spring and autumn of 1995. On the basis of these data, waterlevel contour lines were drawn and the direction of groundwater flow was determined.Three lithologic sections through the subbasins were constructed from drillers' logs of 26 wells.

Water-Resources Investigations Report↗
USGS2015

Mercury, monomethyl mercury, and dissolved organic carbon concentrations in surface water entering and exiting constructed wetlands treated with metal-based coagulants, Twitchell Island, California

Coagulation with metal-based salts is a practice commonly employed by drinking-water utilities to decrease particle and dissolved organic carbon concentrations in water. In addition to decreasing dissolved organic carbon concentrations, the effectiveness of iron- and aluminum-based coagulants for decreasing dissolved concentrations both of inorganic and monomethyl mercury in water was demonstrated in laboratory studies that used agricultural drainage water from the Sacramento–San Joaquin Delta of California. To test the effectiveness of this approach at the field scale, nine 15-by-40 ‑ meter wetland cells were constructed on Twitchell Island that received untreated water from island drainage canals (control) or drainage water treated with polyaluminum chloride or ferric sulfate coagulants. Surface-water samples were collected approximately monthly during November 2012–September 2013 from the inlets and outlets of the wetland cells and then analyzed by the U.S. Geological Survey for total concentrations of mercury and monomethyl mercury in filtered (less than 0.3 micrometers) and suspended-particulate fractions and for concentrations of dissolved organic carbon. In the control wetland cells, total mercury concentrations in filtered water samples ranged from 0.94 to 2.47 nanograms per liter (ng/L) at the control inlets and from 0.84 to 2.63 ng/L at the control outlets, and particulate total mercury concentrations in water ranged from 0.27 to 1.49 ng/L at the control inlets and from 0.17 to 1.11 ng/L at the control outlets. Monomethyl mercury concentrations in filtered water ranged from 0.16 to 0.88 ng/L at the control inlets and from 0.13 to 1.30 ng/L at the control outlets; particulate monomethyl mercury concentrations in water ranged from 0.03 to 0.24 ng/L at the control inlets and from 0.03 to 0.23 ng/L at the control outlets. Dissolved organic carbon concentrations in water ranged from 7.9 to 26.7 milligrams per liter at the control inlets and from 8.5 to 28.0 milligrams per liter at the control outlets. Following coagulation, but prior to passage through the wetland cells, coagulation treatments transferred dissolved mercury and carbon to the particulate fraction relative to untreated source water: at the wetland cell inlets, the coagulation treatments decreased concentrations of filtered total mercury by 59–76 percent, filtered monomethyl mercury by 40–70 percent, and dissolved organic carbon by 65–86 percent. Passage through the wetland cells decreased the particulate fraction of mercury in wetland cells that received coagulant-treated water. Changes in total mercury, monomethyl mercury, and dissolved organic carbon concentrations resulting from wetland passage varied both by treatment and season. Despite increased monomethyl mercury in the filtered fraction during wetland passage between March and August, the coagulation-wetland systems generally decreased total mercury (filtered plus particulate) and monomethyl mercury (filtered plus particulate) concentrations relative to source water. Coagulation—either alone or in association with constructed wetlands—could be an effective way to decrease concentrations of mercury and dissolved organic carbon in surface water as well as the bioavailability of mercury in the Sacramento–San Joaquin Delta.

California↗
USGS2010

Using Landsat satellite data to support pesticide exposure assessment in California

Background The recent U.S. Geological Survey policy offering Landsat satellite data at no cost provides researchers new opportunities to explore relationships between environment and health. The purpose of this study was to examine the potential for using Landsat satellite data to support pesticide exposure assessment in California. Methods and Results We collected a dense time series of 24 Landsat 5 and 7 images spanning the year 2000 for an agricultural region in Fresno County. We intersected the Landsat time series with the California Department of Water Resources (CDWR) land use map and selected field samples to define the phenological characteristics of 17 major crop types or crop groups. We found the frequent overpass of Landsat enabled detection of crop field conditions (e.g., bare soil, vegetated) over most of the year. However, images were limited during the winter months due to cloud cover. Many samples designated as single-cropped in the CDWR map had phenological patterns that represented multi-cropped or non-cropped fields, indicating they may have been misclassified. Conclusions We found the combination of Landsat 5 and 7 image data would clearly benefit pesticide exposure assessment in this region by 1) providing information on crop field conditions at or near the time when pesticides are applied, and 2) providing information for validating the CDWR map. The Landsat image time-series was useful for identifying idle, single-, and multi-cropped fields. Landsat data will be limited during the winter months due to cloud cover, and for years prior to the Landsat 7 launch (1999) when only one satellite was operational at any given time. We suggest additional research to determine the feasibility of integrating CDWR land use maps and Landsat data to derive crop maps in locations and time periods where maps are not available, which will allow for substantial improvements to chemical exposure estimation.

California↗
USGS1980

Irrigation water supply for the Yurok Indians, Resighini Rancheria, Klamath, California

A required 1,100 gallons of water per minute for irrigating agricultural lands used by the Coast Indian Community on the Resighini Rancheria near Klamath, Califomia, cannot be developed from wells. However, the required quantity of water might be developed from a trench installed in sand and gravel deposits that are hydraulically connected with the Klamath River.

California↗
USGS2013

Changes in types and area of postharvest flooded fields available to waterbirds in Tulare Basin, California

Conservation efforts to restore historic waterbird distribution and abundance in the Central Valley of California require information on current and historic areas of waterbird habitat. To provide this information, we mapped the area of agricultural fields in the vicinity of the historic Tulare Lake Bed in the Tulare Basin, California, that were treated postharvest with two different flooding regimes that varied in depth and duration of water applied (, 1 cm to 1.5 m water for longer than 1 wk [FLD]; , 1 to 15 cm water for 1 wk or less [IRG]) during August–March 1991–1994 and 2005–2006. We compared our results with published estimates for 1976–1980 and 1981–1987. Area and crops treated postharvest with FLD or IRG flooding differed among years and months. Overall for August through March, weekly area of FLD fields averaged 1,671 ha in 1976–1980 but declined to about half that in later years; the decline was most severe during January–March. Cotton was primarily treated with IRG flooding and comprised 47–95% of the total IRG field area. Other crops were primarily treated with FLD flooding; tomato replaced safflower in 2005–2006. These documented declines since the 1970s in area of FLD fields and changes in crops being flooded postharvest reduce the carrying capacity of the Tulare Basin for waterbirds, a situation that will need to be reversed for restoration of historic waterbird distribution in the Central Valley to be viable. If maintaining agricultural production is a priority and agricultural drainage waters can be disposed of safely, then increasing the extent of FLD grain fields would provide the most benefit for wintering waterbirds; otherwise, restoring and providing adequate water supplies to managed wetlands would most benefit waterbirds

California↗
USGS2013

Economic impacts of the SAFRR tsunami scenario in California: Chapter H in The SAFRR (Science Application for Risk Reduction) Tsunami Scenario

This study evaluates the hypothetical economic impacts of the SAFRR (Science Application for Risk Reduction) tsunami scenario to the California economy. The SAFRR scenario simulates a tsunami generated by a hypothetical magnitude 9.1 earthquake that occurs offshore of the Alaska Peninsula (Kirby and others, 2013). Economic impacts are measured by the estimated reduction in California’s gross domestic product (GDP), the standard economic measure of the total value of goods and services produced. Economic impacts are derived from the physical damages from the tsunami as described by Porter and others (2013). The principal physical damages that result in disruption of the California economy are (1) about $100 million in damages to the twin Ports of Los Angeles (POLA) and Long Beach (POLB), (2) about $700 million in damages to marinas, and (3) about $2.5 billion in damages to buildings and contents (properties) in the tsunami inundation zone on the California coast. The study of economic impacts does not include the impacts from damages to roads, bridges, railroads, and agricultural production or fires in fuel storage facilities because these damages will be minimal with respect to the California economy. The economic impacts of damage to other California ports are not included in this study because detailed evaluation of the physical damage to these ports was not available in time for this report. The analysis of economic impacts is accomplished in several steps. First, estimates are made for the direct economic impacts that result in immediate business interruption losses in individual sectors of the economy due to physical damage to facilities or to disruption of the flow of production units (commodities necessary for production). Second, the total economic impacts (consisting of both direct and indirect effects) are measured by including the general equilibrium (essentially quantity and price multiplier effects) of lost production in other sectors by ripple effects upstream and downstream along the supply chain. An appropriate measure of the economic impacts on the California economy for the SAFRR tsunami scenario is the reduction in GDP. The economic impacts are first calculated without resilience, the ability of the economy to adjust to disruptions in ways that mute potential negative impacts. There are many types of resilience, including using existing inventories of materials, using unused capacity, conserving inputs, substituting for disrupted supplies, recapturing production after the disruption is restored, and many others. A method for estimating resilience, identified in the port system and sectors affected by property damages, is applied to indicate potential reductions of direct and total economic impacts. In this SAFRR tsunami scenario analysis of economic impacts to California, we implement established techniques used to model the economic impacts for two previous U.S. Geological Survey (USGS) scenarios: the southern California Shakeout earthquake (Rose and others, 2011) and the California ARkStorm severe winter storm (Sue Wing and others, written commun., 2013). For the SAFRR tsunami scenario, we reviewed the relevant studies that assess economic impacts from previous tsunami events affecting California and elsewhere and estimate the economic impacts of potential tsunami and other threats to POLA and POLB. To our knowledge, assessment of impacts to the California economy from distant source tsunamis does not exist. Previous tsunamis, including those from the 1960 Chile earthquake, the 1964 Alaska earthquake, the 2008 Chile earthquake and the 2011 Japan earthquake, had only relatively minor or very localized severe damage (such as that in Crescent City in 1964), and no studies of the economic impacts were completed. A rare study of the economic impacts of a tsunami event has recently been produced for the Tohoku earthquake and tsunami (Kajitani and others, 2013). Quarterly declines in Japan’s GDP are observed to peak at ‒1.63 percent in the second quarter after the event and stagnate for the rest of the year. The majority of the economic impacts are attributed to the tsunami rather than the earthquake. The hardest hit sectors are identified as agriculture, fisheries, manufacturing, retail, and tourism. Other relevant studies have focused on the economic impacts of threats that close POLA and POLB. We find one analysis of a potential tsunami scenario affecting the California economy through disruption of port operations. Borrero and others (2005) estimated economic impacts to the southern California economy of $7 to $40 billion from a locally generated tsunami that closes POLA and POLB for as much as 1 year. There have also been several studies of the economic impacts of non-tsunami events affecting POLA and POLB. Analyses of an 11-day labor lockout produced a range of estimated national impacts of as much as $1.94 billion/day (Park and others 2008, Martin Associates 2001). Examination of a potential terrorist attack that closes the San Pedro port for 1 month yielded a $29 billion impact to the California economy (Park, 2008). These studies have reinforced the importance of recognizing economic resilience in economic impact analyses. Hall (2004) criticized the upper-end estimate of national economic impacts from the labor lockout based on model shortcomings that neglected short-run substitution behavior and fixed the long-run economic behaviors. Following the 2011 Japanese tsunami, resilience was observed in the forms of rapid recovery of manufacturing sectors, energy conservation, and insurance (Kajitani and others, 2013).

California↗
USGS2025

Pesticide contamination detected across five wildlife refuges in the Sacramento Valley of California

An important goal for the applied ecological sciences is to understand the extent to which the biodiversity on conserved or managed lands is exposed to anthropogenic stressors. Among the various categories of conserved lands in the United States, the National Wildlife Refuge System is focused on the protection and management of native wildlife and plant populations. Refuge lands can be associated with wetlands and, especially in California, tend to be near areas of intense human use, including agriculture. The proximity of refuges to cultivated lands results in potential exposure to pesticide drift, which increases the possibility of non-target effects on plants and wildlife. We used a passive sampler approach to quantify aerial pesticide deposition during 28 days in spring of 2023, across five refuges in the Sacramento Valley of California. Pesticides were detected across all refuges and plots within the study area, with 36 individual compounds identified, including insecticides, herbicides, and fungicides, from 176 silicone bands from 49 plots. Distance to agriculture was not an important predictor in our models for most indices of contamination. However, our models revealed that the nearest crop type was an important mediator of the importance of distance to agriculture, as fungicide contamination decreased with distance to agriculture only when orchards were the nearest crop type. The overall lack of distance effects suggests that the interior of refuges in the study area do not necessarily provide more protection from pesticides than refuge edges, although larger refuges could offer more protection. We currently lack information on how the level of contamination found herein is biologically relevant to wildlife, and ongoing monitoring efforts have found productive communities of insects in the study area. The results of this study provide a foundation for future investigations on refuges to analyze impacts of specific pesticide compounds on plants and wildlife.

California↗
USGS1990

National water summary 1987: Hydrologic events and water supply and use

Water use in the United States, as measured by freshwater withdrawals in 1985, averaged 338,000 Mgal/d (million gallons per day), which is enough water to cover the 48 conterminous States to a depth of about 2.4 inches. Only 92,300 Mgal/d, or 27.3 percent of the water withdrawn, was consumptive use and thus lost to immediate further use; the remainder of the withdrawals (72.7 percent) was return flow available for reuse a number of times as the water flowed to the sea. The 1985 freshwater withdrawals were much less than the average 30 inches of precipitation that falls on the conterminous States each year; consumptive use accounted for only 7 percent of the estimated annual runoff of 1,230,000 Mgal/d. Nonetheless, as the State summaries on water supply and use clearly show, water is not always available when and where it is needed. Balancing water demands with available water supplies constitutes one of the major resource allocation issues that will face the United States in the coming decade. Of the 1985 freshwater withdrawals, 78.3 percent (265,000 Mgal/d) came from surface-water sources (streams and lakes), and 21.7 percent (73,300 Mgal/d) came from ground water. Surface water provided drinking water for about 47 percent of the Nation's total population. It was the source of 59.9 percent of the Nation's public-supply systems. For self-supplied withdrawals, surface water accounted for 1.6 percent of the domestic and commercial uses; 64.0 percent of the industrial and mining use; 99.4 percent of the thermoelectric generation withdrawals, mainly for cooling water; and 65.6 percent of the agricultural withdrawals. Eight States accounted for 43 percent of the surface-water use; California, Colorado, and Idaho used surface water primarily for irrigation, and Dlinois, Michigan, Ohio, Pennsylvania, and Texas used surface-water primarily for cooling condensers or reactors in thermoelectric plants. Ground water provided drinking water for 53 percent of the Nation's total population and nearly all the rural population. It was the source of 40.1 percent of the public-supply systems withdrawals. For self-supplied withdrawals, ground water accounted for 11.3 percent of the domestic and commercial use, 17.3 percent of the industrial and mining withdrawals, less than 1 percent of the thermoelectric generation withdrawals, and 34.4 percent of the agricultural withdrawals (irrigation and livestock). Eight States Arizona, Arkansas, California, Florida, Idaho, Kansas, Nebraska, and Texas accounted for 66 percent of the ground water used. In each of those States, as in many other States, irrigation was the major use of ground water. Each offstream-use category described in the State summaries public supply, domestic and commercial, industrial and mining, thermoelectric power, and agriculture (irrigation and livestock) followed its own geographic pattern as described below. Consumptive use of water effectively removes the water from immediate further use downstream of the withdrawal point. Of the total amount of consumptive water use in 1985, agricultural use accounted for about 82.5 percent. More than one-half (53 percent) of irrigation water is consumptively used by evapotranspiration or is incorporated into the crop. This is a good indication of the effect that irrigated agriculture can have in a river basin where irrigation is a major activity. The availability of return flows for reuse depends largely on where the water reenters the system. If the return flows are discharged to a stream, they usually can be reused; if they are discharged to a saltwater estuary, they are effectively lost to further use because of water-quality degradation just as if the water had been consumptively used. Similarly, water that recharges a highly transmissive aquifer can be available for reuse either through pumpage from a well or as discharge to a local stream. Thus, much of the water withdrawn for different uses can and does become available for further use although the quality might degrade with each additional use. The allocation and the management of water resources are the responsibilities of the individual States and water institutions within the States. These institutions are evolving in response to the challenges of water management problems. As the individual State summaries indicate, recent State legislation deals with facilitating water transfers within the States as a means of reducing imbalances between water supplies and use, with emphasizing water conservation in times of drought and at places where groundwater depletion is a problem of long standing, and with reducing threats to public health and the environment from water pollution. Most of the State summaries indicate the expectation that water use will continue to increase in the future and that water contamination will continue to be a major water concern. Both issues will require increasingly intensive water management in the future. Whether the water resources under management are considered to be fully appropriated or over appropriated, as in some Western States, or whether the resource could support additional development, as is the situation in most States, improved water-use information will play a key role in future water management efforts.

Water Supply Paper↗
USGS2021

Implementation plan for the southern Pacific Border and Sierra-Cascade Mountains provinces

Introduction The National Cooperative Geologic Mapping Program (NCGMP) is publishing a strategic plan titled Renewing the National Cooperative Geologic Mapping Program as the Nation’s Authoritative Source for Modern Geologic Knowledge (Brock and others, in press). The plan provides a vision, mission, and goals for the program during the years 2020–2030, which are: Vision .—Create an integrated, three-dimensional, digital geologic map of the United States. Mission .—Characterize, interpret, and disseminate a national geologic framework model of the Earth through geologic mapping. Goal .—Focus on geologic mapping as a core function of the U.S. Geological Survey (USGS) within the long-term vision of adequately mapping the Nation’s geologic framework in three dimensions. In order to achieve the goals outlined in the strategic plan, the NCGMP has developed an implementation plan. This plan will guide the annual review of projects carried out by USGS staff (FEDMAP) described in the plan and the development of the annual FEDMAP prospectus that will ensure the effective application of the NCGMP strategy. This publication describes the implementation plan of the NCGMP strategy for the southern Pacific Border and Sierra-Cascade Mountains provinces, as defined by Fenneman (1917, 1928, and 1946). This implementation plan focuses on the geology of California and a sliver of Nevada surrounding Lake Tahoe. The southern Pacific Border and Sierra-Cascade Mountains provinces encompass the varied landscapes of the high Sierra Nevada, the Central Valley, and Coast Ranges in northern and central California and the Peninsular Ranges, Continental Borderland, Los Angeles Basin-San Gabriel-San Bernardino valleys, western and central Transverse Ranges, and northernmost Salton Trough in southern California. Societal demands create a need for earth-science data in each of these landscapes. The broader San Francisco Bay area, Central Valley, Los Angeles-San Gabriel-San Bernardino lowlands, and the coastal lowlands that border the Peninsular Ranges are densely populated (about 30 million people) areas at high risk of natural hazards. The mountains of the Sierra Nevada, Peninsular Ranges, and Transverse Ranges, and the coast all provide numerous recreational opportunities that attract visitors from around the world, whereas previously these ranges attracted people to mine their resources. The agricultural capacity of the Central Valley is a critical resource for the Nation that is increasingly water limited. The southern. Pacific Border and Sierra-Cascade Mountains provinces, at the edge of the North American continent, were profoundly influenced by subduction zone tectonics during the Mesozoic and early Cenozoic (ongoing in northernmost California) and subsequently by the inception, development, and present activity of the San Andreas transform margin system. Although the geology of this region is the poster child of fundamental conceptual models of subduction zone complexes, forearc basins, ophiolite obductions, magmatic arcs, and suspect terranes, as well as hosting one of Earth’s most notorious continental transform faults—the San Andreas Fault—important questions that have important societal consequences remain to be answered. Most of California’s population reside in these provinces and live within 30 miles of an active fault (according to www.earthquakeauthority.com ) yet new faults continue to be discovered, highlighting the importance of deformation off the main San Andreas Fault. Bedrock, surficial, and three-dimensional (3D) geologic maps depicting stratigraphic structure and depth to crystalline basement rocks provide critical context and information for understanding fault rupture, distributed deformation, fault connectivity, and history in addition to providing crucial data that enable forecasting of shaking amplitude and length from hypothetical earthquake scenarios. The tectonic evolution of California produced not only stunning mountains, with associated hazards from landslides and active volcanoes, but also fertile valleys that make California the top agricultural producer in the country in terms of cash receipts (according to www.ers.usda.gov/faqs ). These valleys lie atop large basins that not only store groundwater but, in many cases, host oil and gas fields, contributing to the fourth highest hydrocarbon production by State in the country in 2016 (according to https://www.aei.org/carpe-diem/animated-chart-of-us-oil-production-by-state-1981-2017 ). Water is a key resource increasingly stressed by growing agricultural, industrial, and residential needs. Warmer and drier conditions have led to an increased reliance on extracting groundwater resources, whose availability and quality are dictated at the first order by the 3D spatial distribution of bedrock and Quaternary surficial deposits. Thus, assessment of this critical resource is inextricably tied to knowledge of the surficial and subsurface geologic structure and material types.

California, Nevada↗
USGS2024

Machine learning and new-generation spaceborne hyperspectral data advance crop type mapping

Hyperspectral sensors provide near-continuous spectral data that can facilitate advancements in agricultural crop classification and characterization, which are important for addressing global food and water security issues. We investigated two new-generation hyperspectral sensors, Germany’s Deutsches Zentrum für Luft‐ und Raumfahrt Earth Sensing Imaging Spectrometer (DESIS) and Italy’s PRecursore IperSpettrale della Missione Applicativa (PRISMA), within California's Central Valley in August 2021 focusing on five irrigated agricultural crops (alfalfa, almonds, corn, grapes, and pistachios). With reference data from the U.S. Department of Agriculture Cropland Data Layer, we developed a spectral library of the crops and classified them using three machine learning algorithms (support vector machines [SVM], random forest [RF], and spectral angle mapper [SAM]) and two philosophies: 1. Full spectral analysis (FSA) and 2. Optimal hyperspectral narrowband (OHNB) analysis. For FSA, we used 59 DESIS four-bin product bands and 207 of 238 PRISMA bands. For OHNB analysis, 9 DESIS and 16 PRISMA nonredundant OHNBs for studying crops were selected. FSA achieved only 1% to 3% higher accuracies relative to OHNB analysis in most cases. SVM provided the best results, closely followed by RF. Using both DESIS and PRISMA image OHNBs in SVM for classification led to higher accuracy than using either image alone, with an overall accuracy of 99%, producer’s accuracies of 94% to 100%, and user's accuracies of 95% to 100%.

California↗
USGS1998

Hydrogeology, water quality, water budgets, and simulated responses to hydrologic changes in Santa Rosa and San Simeon Creek ground-water basins, San Luis Obispo County, California

Santa Rosa and San Simeon Creeks are underlain by thin, narrow ground-water basins that supply nearly all water used for local agricultural and municipal purposes. The creeks discharge to the Pacific Ocean near the northwestern corner of San Luis Obispo County, California. The basins contain heterogeneous, unconsolidated alluvial deposits and are underlain by relatively impermeable bedrock. Both creeks usually stop flowing during the summer dry season, and most of the pumpage during that time is derived from ground-water storage. Annual pumpage increased substantially during 1956?88 and is now a large fraction of basin storage capacity. Consequently, dry-season water levels are lower and the water supply is more vulnerable to drought. The creeks are the largest source of ground-water recharge, and complete basin recharge can occur within the first few weeks of winter streamflow. Agricultural and municipal pumpages are the largest outflows and cause dry-season water-level declines throughout the San Simeon Basin. Pumping effects are more localized in the Santa Rosa Basin because of subsurface flow obstructions. Even without pumpage, a large quantity of water naturally drains out of storage at the upper ends of the basins during the dry season. Ground water is more saline in areas close to the coast than in inland areas. Although seawater intrusion has occurred in the past, it probably was not the cause of high salinity in 1988?89. Ground water is very hard, and concentrations of dissolved solids, chloride, iron, and manganese exceed drinking-water standards in some locations. Probability distributions of streamflow were estimated indirectly from a 120-year rainfall record because the periods of record for local stream-gaging stations were wetter than average. Dry-season durations with recurrence intervals between 5 and 43 years are likely to dry up some wells but not cause seawater intrusion. A winter with no streamflow is likely to occur about every 32 years and to result in numerous dry wells, seawater intrusion, and subsidence. Digital ground-water-flow models were used to estimate several items in the ground-water budgets and to investigate the effects of pumpage and drought. The models also were used to investigate the hydrologic effects of selected water-resources management alternatives. Selection of alternatives was not constrained by issues related to water rights, which were under dispute during the study. Increases in the area and intensity of irrigation could increase agricultural water demand by 26 to 35 percent, an increase that would lower water levels by as much as 10 feet and possibly cause subsidence in the lower Santa Rosa Basin. An additional municipal well in the lower Santa Rosa Basin could withdraw 100 acre-feet per year without causing seawater intrusion, but subsidence might occur. Transferring 270 acre-feet per year of treated wastewater from a percolation area near the coast to an area about 0.5 mile upstream of the municipal well field in the San Simeon Basin could raise upstream water levels by as much as 12 feet without causing significant water-table mounding or seawater intrusion. Decreases in agricultural pumping after a winter without streamflow could prevent seawater intrusion while allowing municipal pumping to continue at normal rates.

Water-Resources Investigations Report↗
USGS2020

Shaping land use change and ecosystem restoration in a water-stressed agricultural landscape to achieve multiple benefits

Irrigated agriculture has grown rapidly over the last 50 years, helping food production keep pace with population growth, but also leading to significant habitat and biodiversity loss globally. Now, in some regions, land degradation and overtaxed water resources mean historical production levels may need to be reduced. We demonstrate how analytically supported planning for habitat restoration in stressed agricultural landscapes can recover biodiversity and create co-benefits during transitions to sustainability. We apply our approach in California's San Joaquin Valley where groundwater regulations are driving significant land use change. We link agricultural-economic and land use change models to generate plausible landscapes with different cropping patterns, including temporary fallowing and permanent retirement. We find that a large fraction of the reduced cultivation is met through temporary fallowing, but still estimate over 86,000 hectares of permanent retirement. We then apply systematic conservation planning to identify optimized restoration solutions that secure at least 10,000 hectares of high quality habitat for each of five representative endangered species, accounting for spatially varying opportunity costs specific to each plausible future landscape. The analyses identified consolidated areas common to all land use scenarios where restoration could be targeted to enhance habitat by utilizing land likely to be retired anyway, and by shifting some retirement from regions with low habitat value to regions with high habitat value. We also show potential co-benefits of retirement (derived from avoided nitrogen loadings and soil carbon sequestration), though these require careful consideration of additionality. Our approach provides a generalizable means to inform multi-benefit adaptation planning in response to agricultural stressors.

California↗
USGS2013

The role of irrigation runoff and winter rainfall on dissolved organic carbon loads in an agricultural watershed

We investigated the role of land use/land cover and agriculture practices on stream dissolved organic carbon (DOC) dynamics in the Willow Slough watershed (WSW) from 2006 to 2008. The 415 km 2 watershed in the northern Central Valley, California is covered by 31% of native vegetation and the remaining 69% of agricultural fields (primarily alfalfa, tomatoes, and rice). Stream discharge and weekly DOC concentrations were measured at eight nested subwatersheds to estimate the DOC loads and yields (loads/area) using the USGS developed stream load estimation model, LOADEST. Stream DOC concentrations peaked at 18.9 mg L −1 during summer irrigation in the subwatershed with the highest percentage of agricultural land use, demonstrating the strong influence of agricultural activities on summer DOC dynamics. These high concentrations contributed to DOC yields increasing up to 1.29 g m −2 during the 6 month period of intensive agricultural activity. The high DOC yields from the most agricultural subwatershed during the summer irrigation period was similar throughout the study, suggesting that summer DOC loads from irrigation runoff would not change significantly in the absence of major changes in crops or irrigation practices. In contrast, annual DOC yields varied from 0.89 to 1.68 g m −2 yr −1 for the most agricultural watershed due to differences in winter precipitation. This suggests that variability in the annual DOC yields will be largely determined by the winter precipitation, which can vary significantly from year to year. Changes in precipitation patterns and intensities as well as agricultural practices have potential to considerably alter the DOC dynamics.

California↗
USGS2024

Land-use interactions, Oil-Field infrastructure, and natural processes control hydrocarbon and arsenic concentrations in groundwater, Poso Creek Oil Field, California, USA

Like many hydrocarbon production areas in the U.S., the Poso Creek Oil Field in California includes and is adjacent to other land uses (agricultural and other developed lands) that affect the hydrology and geochemistry of the aquifer overlying and adjacent to oil development. We hypothesize that the distributions of hydrocarbons and arsenic in groundwater in such areas will be controlled by complex interactions between mixed land uses, oil-field infrastructure, and natural processes. In 2020–2021, samples of groundwater and surface water were collected and analyzed for a large suite of inorganic and organic chemicals and isotope and gas tracers to test this hypothesis. Those data are supplemented with ancillary data on historical geochemistry, hydrology, geology, and oil-field infrastructure. Hydrocarbons in groundwater (e.g., methane through pentane gases and benzene) are associated with natural processes (e.g., fault offsets or transition in sediment depositional environment) and oil-field infrastructure (e.g., fluid-migration pathways associated with uncemented annulus in oil wells or unlined pits). Arsenic concentrations >10 μg per liter (μg/L; maximum concentration 12.9 μg/L) are associated with natural processes in old, high-pH groundwater, and more recent recharge of water from natural and/or engineered recharge processes. Along the southwest margin of the oil field, pumping for drinking-water and irrigation supplies in combination with engineered groundwater recharge produce a depression in groundwater elevations where groundwater with elevated sulfate concentrations from agricultural areas and groundwater with hydrocarbons from the oil field mix to produce a zone of sulfate reduction that removes hydrocarbons and arsenic from groundwater but produces elevated sulfide (S 2- ) concentrations (maximum concentration 29 mg per liter, mg/L). In this study, multiple approaches were required to resolve the overlapping effects of land uses, oil-field infrastructure, and natural processes on the distributions of hydrocarbons and arsenic in groundwater. The combined use of geographic, historical, physical, chemical, isotopic, and other information to constrain processes could be a useful approach for studies in other hydrocarbon-production areas. This is particularly important where land uses affect aquifer hydrology to an extent that causes mixing of groundwaters with different chemical compositions.

California↗