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USGS2016

Modeled historical land use and land cover for the conterminous United States

The landscape of the conterminous United States has changed dramatically over the last 200 years, with agricultural land use, urban expansion, forestry, and other anthropogenic activities altering land cover across vast swaths of the country. While land use and land cover (LULC) models have been developed to model potential future LULC change, few efforts have focused on recreating historical landscapes. Researchers at the US Geological Survey have used a wide range of historical data sources and a spatially explicit modeling framework to model spatially explicit historical LULC change in the conterminous United States from 1992 back to 1938. Annual LULC maps were produced at 250-m resolution, with 14 LULC classes. Assessment of model results showed good agreement with trends and spatial patterns in historical data sources such as the Census of Agriculture and historical housing density data, although comparison with historical data is complicated by definitional and methodological differences. The completion of this dataset allows researchers to assess historical LULC impacts on a range of ecological processes.

Journal of Land Use Science↗

USGS2019

Managed aquifer recharge in snow-fed river basins: What, why and how?

What does climate change mean for snow-fed river basins? Climate change poses unique challenges in snow-fed river basins across the western United States because the majority of water supply originates as snow (Dettinger, Udall, & Georgakakos, 2015). In the Sierra Nevada, recent observations include changes in snow accumulation and snowmelt, and shifts in peak streamflow timing (Barnhart et al., 2016; Hatchett et al., 2017; Kim & Jain, 2010; McCabe, Wolock, & Valentin, 2018; Mote, Li, Lettenmaier, Xiao, & Engel, 2018). Such changes upstream alter surface water deliveries downstream, as well as groundwater recharge utilized as both primary and supplemental water supply (Godsey et al., 2014; Harpold, 2016; Jasechko et al., 2014). basin where snowmelt runoff produces substantial water supply to meet diverse agricultural, environmental and urban water demand (Figure 1). The East and West Forks join at the confluence of the Carson River near the north end of the Carson Valley, a rich agricultural region (40,000 acres) that grows primarily alfalfa hay. The majority of irrigators rely on surface water delivered through a network of earthen ditches constructed in the mid-19th and early 20th centuries. Flow through these earthen networks and the practice of flood irrigation contribute significantly to groundwater recharge. Because no upstream surface water reservoirs exist, snowpack that accumulates through winter and melts slowly through spring has acted as a “natural” reservoir, providing ample supply through the summer irrigati agricultural, environmental and urban water demand (Figure 1). The East and West Forks join at the confluence of the Carson River near the north end of the season. Some irrigators have permitted access to supplemental groundwater that is useful during periods of drought for augmenting shortfalls in surface water delivery. Groundwater is the primary source of municipal and industrial water supply for surrounding communities (e.g., Carson City, Minden, Gardnerville, Dayton). Across the basin, water use is highly regulated through federal, tribal, state and local water-sharing agreements based on prior appropriation doctrine (Wilds, 2014). Carson River surface water allocations follow the Alpine Decree, initiated by the United States Department of Interior in 1925 and signed into law in 1980, following 55 years of litigation, to adjudicate surface water rights to individual parties (NDWP, 1999). The Alpine Decree acknowledges return flows to lower river segments, and thus each river segment is distributed autonomously. This means that the most junior water right on an upper segment can be fulfilled before considering the most senior water right on a lower segment. Ultimately, the ruling is at the discretion of the Federal Water Master to satisfy the needs of each water right Downstream of Carson Valley, surface water flows are stored in Lahontan Reservoir, the nation’s first desert reclamation project (est. 1906), where releases are managed to meet the Newland’s Project irrigation water demand and for environmental use on the Stillwater National Wildlife Refuge. Flows from the Carson River are supplemented through diversions from the Truckee River via the Truckee Canal, resulting in a trans-basin water supply system. How is the Water for the Seasons research program informing snow-fed river basin communities? In the Truckee-Carson River System, researchers and local water managers are working together to assess climate change impacts to water supply and explore how model simulations can produce useful information to support local climate adaptation. Twelve key water managers represent agricultural, environmental, urban and regulatory water-use communities, and bring to the table diverse input and perspectives on how to adapt to climate change. Hydrologists use this input to craft scenarios and simulations that meet the information needs of local water managers. Biannual workshops provide an opportunity for information exchange, where researchers and key water managers generate new knowledge of river system function. That is, researchers share results of models that examine the physical potential, and managers validate the on-the-ground potential, further informing the research process. Coincident to this research program, the region faced a prolonged drought period (2012-2016) with historically low snowpack, followed by a historic wet year (2017) that brought winter and spring flooding as a result of atmospheric river storm events (Sterle et al., 2019). For the Carson River, an important observation made by managers was that peak streamflow that had traditionally coincided with peak irrigation demands, had shifted to earlier in the spring, with summer baseflow also decreasing (Sterle & Singletary, 2017). Managers shared with researchers concerns over potential future impacts that changing snowpack will have on surface water deliveries and reliance on groundwater, as the region’s population and economy continue to grow. During workshops that occurred over this period, local water managers and researchers discussed ways to evaluate water distribution and use that honors the existing legal framework and accounts for changing snowpack regimes (amount, rain versus snow, timing). In response to managers growing interest, researchers introduced the concept of managed aquifer recharge as one potential strategy to adapt and enhance regional water sustainability. What is managed aquifer recharge? Simply stated, managed aquifer recharge is the intentional recharge of structures to spread water over agricultural lands, allowing water to naturally infiltrate into the groundwater system (Bouwer, 1999; Niswonger et al., 2017). The latter may occur during the irrigation season by applying excess water, or during the nonirrigation season when evapotranspiration losses are low. Figure 2 illustrates managed aquifer recharge in a snow-fed river basin, where streamflow generated from snowmelt runoff is diverted to agricultural lands to recharge the aquifer. Such flood irrigation practices, including water delivery through earthen ditch networks, provide incidental but significant aquifer recharge through seepage and deep drainage beneath fields (Niswonger, Allander, & Jeton, 2014). The effects of managed aquifer recharge can vary depending on the location and intensity of practice. For example, implementing managed aquifer recharge water into the groundwater system (Dillon, 2009). This differs from the incidental recharge that may occur as part of normal irrigation practices. Managed recharge may occur by injection into the aquifer through existingwells, or by using existing conveyance adjacent to/along the river’s floodplain has the potential to enhance late-season instream flows due to increased return flows, resulting in greater downstream deliveries as well as improving ecological conditions (Niswonger et al., 2017). Implementing managed aquifer recharge away from the river’s floodplain has the potential to enhance groundwater supply which is increasingly relied upon during surface water shortage (Green et al., 2011), by storing water in available aquifer space in the deep aquifer. At the basin scale, managed aquifer recharge may lead to regional groundwater sustainability. Is the Carson River Basin a candidate for managed aquifer recharge? The physical limitations to implementing managed aquifer recharge in the Carson River Basin hinges on three key factors. The first factor relates to the physical connectivity between rivers and streams, and the irrigation delivery network of canals and ditches that divert water to agricultural lands (Niswonger et al., 2017). In the Carson River Basin the mechanisms for getting water to fields is already in place. Thus, intentionally routing high flows that occur in wet years through this system during the nonirrigation season would mimic what occurs naturally during the irrigation season. The second factor relates to the occurrence of atmospheric river storm events that deliver large amounts of precipitation to the region, much greater than average (Dettinger et al., 2015). With increased frequency and intensity projected under a warmer climate, such events have the potential to produce excess water over short periods of time that could be stored through mechanisms such as managed aquifer recharge (Niswonger et al., 2017). The third factor relates to the change in snowpack accumulation and shifts in snowmelt timing observed elsewhere in the Sierra Nevada (e.g., Godsey et al., 2014; Mote et al., 2018). Having a mechanism in place to maximize use of earlier snowmelt and shifts in streamflow timing could be advantageous and enhance regional groundwater sustainability. As part of the Water for the Seasons study, a hypothetical scenario was developed to determine the feasibility of managed aquifer recharge in the Carson River Basin, assuming no legal constraints. During “wet” or above-average water years, irrigators in the Upper Carson Valley would divert high flows and spread water over agricultural lands during the nonirrigation season. Assuming flows are abundant and “early,” diversions would begin prior to the growing season, when water would otherwise flow downstream to the Lahontan Reservoir. During “dry” years or drought periods, when surface water availability is less, irrigators in the Upper Carson Valley could augment surface water shortages with groundwater, allowing available surface water flows to flow downstream. Researchers hypothesize the amount of water has the potential to boost baseflow to support environmental instream flows, for example. What concerns have local water managers expressed? The hypothetical managed aquifer recharge scenario was presented to water managers in a workshop setting. Presentations included an overview of the hydrologic and operations modeling tools used to evaluate managed aquifer recharge by simulating the timing and distribution of water in the upper watershed. Specifically, in the Upper Carson Valley, a hydrologic model (GSFLOW) simulates streamflow driven by snowmelt, and surface and groundwater interactions, while a river basin operations model (MODSIM) allocates water according to the prior appropriation doctrine in the basin (see Figure 1) (Morway, Niswonger, & Triana, 2016; Niswonger et al., 2017). Integrating these two modeling tools advances the evaluation of climate impacts on water availability in agricultural communities and the resulting impacts of alternative management strategies (Morway et al., 2016). When asked about the viability of managed aquifer recharge, the perspectives of 11 managers varied (Figure 3). Regardless of rating, all managers questioned, “How would thisreally work?” Several managers questioned whether models could simulate the connectivity between surface and groundwater to accurately quantify changes to instream flow. Others raised concerns that managed aquifer recharge violates the Alpine Decree and Nevada Water Law. Still others requested researchers consider alternatives that could work within the confines of current (2019) water law. Managers posed specific questions that should be considered when evaluating the potential for managed aquifer recharge. For example: What triggers implementation of managed aquifer recharge?How “high” or “low” must annual flows be to initiate managed aquifer recharge? When in the water year is this determined? Where exactly in the Carson Valley is managed aquiferre charge possible? For example, what areas away from the floodplain could ensure long-term storage? Can model simulations quantify potential benefits and consequences system-wide?Would this information support decision-making, such as permitting of additional supplemental groundwater rights? How are researchers going to address managers’ research questions? Managers’ perspectives help to validate the on-the-ground potential of particular strategies and further refine alternative management scenarios. For example, understanding that managers are concerned with oversaturated fields helps researchers to define conditions in the model, such as what defines a wet versus “too” wet type of year and where to focus irrigation for managed aquifer recharge. Incorporating these nuances provides more accurate quantification of the potential benefits and consequences for users across the basin. Modeling is underway to simulate managed aquifer recharge scenarios and explore basin-wide implications. Researchers and local water managers will convene to collaboratively review results and further assess whether this or other strategies could work under the confines of existing water law. Subsequent fact sheets will present these findings.

Nevada↗

USGS1989

Agricultural chemicals and prairie pothole wetlands: Meeting the needs of the resource and the farmer -- U.S. perspective

Included are the reasons for concern over the effects of agrichemicals (pesticides and fertilizers) on prairie-pothole wetlands in the United States. Summarized are the results of studies conducted to date on this topic. Identified is additional research needed to assess the impacts of agrichemicals on these wetlands. Included is a discussion of management strategies and initiatives which we believe may minimize inputs of these chemicals and their impacts on wetlands and waterfowl within this portion of the prairie pothole region, while still meeting the needs of the agricultural community.

Transactions of the North American Wildlife and Na↗

USGS1993

Fish meal and alternate sources of protein in fish feeds: Update 1993

Close to 12% of the world's 6.5 million metric tons of fish meal is used for aquaculture feeds. If current trends continue, roughly 20% to 25% of total world fish meal production could be used for aquaculture by the year 2000. Fish stocks used in fish meal reduction, however, appear to be in worldwide decline. A growing fish farming industry and a stagnating, if not diminishing, supply of fish meal have sobering economic and technologic implications for fish culture. Unless suitable alternate protein sources are found or other animal feeds begin to rely less on fish meal, fish production costs can be expected to increase dramatically. A precedent was set by the poultry industry, the most economically successful and competitive of the animal agriculture industries. Twenty years ago, the poultry industry consumed up to 80% of fish meal supplies. Through deliberate and well-organized research into alternate protein sources, the industry now uses less than 40% of supplies, and the trend is toward complete independence from fish meal. A comparable research effort is needed for aquaculture. Considering the biotechnologies available, plant proteins, processed to remove enzyme inhibitors and other antinutritional factors and properly supplemented with essential amino acids and minerals where needed, could produce results at least equivalent to those obtained with fish meal.

Fisheries↗

USGS2013

Is exposure to cyanobacteria an environmental risk factor for amyotrophic lateral sclerosis and other neurodegenerative diseases?

There is a broad scientific consensus that amyotrophic lateral sclerosis (ALS) is caused by gene-environment interactions. Mutations in genes underlying familial ALS (fALS) have been discovered in only 5–10% of the total population of ALS patients. Relatively little attention has been paid to environmental and lifestyle factors that may trigger the cascade of motor neuron death leading to the syndrome of ALS, although exposure to chemicals including lead and pesticides, and to agricultural environments, smoking, certain sports, and trauma have all been identified with an increased risk of ALS. There is a need for research to quantify the relative roles of each of the identified risk factors for ALS. Recent evidence has strengthened the theory that chronic environmental exposure to the neurotoxic amino acid β-N-methylamino-L-alanine (BMAA) produced by cyanobacteria may be an environmental risk factor for ALS. Here we describe methods that may be used to assess exposure to cyanobacteria, and hence potentially to BMAA, namely an epidemiologic questionnaire and direct and indirect methods for estimating the cyanobacterial load in ecosystems. Rigorous epidemiologic studies could determine the risks associated with exposure to cyanobacteria, and if combined with genetic analysis of ALS cases and controls could reveal etiologically important gene-environment interactions in genetically vulnerable individuals.

Amyotrophic Lateral Sclerosis and Frontotemporal D↗

USGS1995

Chemical and isotopic evolution of a layered eastern U.S. snowpack and its relation to stream-water composition

The chemical, isotopic, and morphologic evolution of a layered snowpack was investigated during the winter of 1993-94 at Sleepers River Research Watershed in Danville, Vermont. The snowpack was monitored at two small basins: a forested basin at 525 m elevation, and an agricultural basin at 292 m elevation. At each site, the snowpack morphology was characterized and individual layers were sampled seven times during the season. Nitrate and 8d18O profiles in the snowpack remained relatively stable until peak accumulation in mid-March, except near the snow surface, where rain-on-snow events caused water and nitrate movement down to impeding ice layers. Subsequently, water and nitrate moved more readily through the ripening snowpack. As the snowpack evolved, combined processes of preferential ion elution, isotopic fractionation, and infiltration of isotopically heavy rainfall caused the pack to become depleted in solutes and isotopically enriched. The release of nitrate and isotopically depleted water was reflected in patterns of nitrate concentrations and ??18O of meltwater and stream water. Results supported data from the previous year which suggested that streamflow in the forested basin during snowmelt was dominated by groundwater discharge.

Biogeochemistry of seasonally snow-covered catchme↗

USGS2008

Environmental presence and persistence of pharmaceuticals: An overview

Emerging contaminants (ECs) in the environment – that is, chemicals with domestic, municipal, industrial, or agricultural sources that are not commonly monitored but may have the potential for adverse environmental effects – is a rapidly growing field of research. The use of “emerging” is not intended to infer that the presence of these compounds in the environment is new. These chemicals have been released into the environment as long as they have been in production or, in the case of hormones and other endogenous compounds, since the rise of animal life. What is emerging is the interest by the scientific and lay communities in the presence of these chemicals in the environment, the analytical capabilities required for detection, and the subtle effects that very small concentrations of these chemicals appear to have on aquatic biota. In December 2006, Environmental Science & Technology devoted an entire special issue (volume 40, number 23) to the topic of ECs, illustrating the increased interest in the subject. Within the EGs, one particular class that has seen a substantial increase in research over the past 10 years is pharmaceuticals and personal-care products (PPCPs). This increased research interest can be demonstrated by several means, including requests for proposals from funding agencies, but the clearest indication of a focused effort to understand the introduction, transformation, and potential health and environmental effects of PPCPs and ECs, in general, is the number of published reports. This increase can be shown by examining six environmental journals that regularly publish PPCP-related papers – Chemosphere , Environmental Science & Technology , Environmental Toxicology and Chemistry , Science of the Total Environment , Water Research , and Water Science and Technology . In 1998 there were 22 papers published on pharmaceuticals, antibiotics, or drugs in these 6 journals; by 2006, this number increased sixfold to 132 papers (Figure 1.1). This growth can be attributed to a number of factors. The presence of pharmaceuticals in surface-water samples from Europe and the United States was documented in several sentinel papers. These ground-breaking works encouraged other scientists to examine the rivers, streams, lakes, and reservoirs in their regions for such chemicals. In addition, the intense public attention paid to news reports on the environmental detections of these chemicals and possible effects of aquatic life has made this issue visible to the wastewater-treatment, drinking-water treatment, and regulatory communities. This has driven the funding bodies associated with these communities to fund studies or request proposals that address the presence, fate, and effects of PPCPs in aquatic systems. The release of the first comprehensive reconnaissance of pharmaceuticals and other wastewater contaminants in the United States provides an example of the intense media interest in this topic. Within 6 days on online publication of this study, 72 newspapers across the United States had published articles describing the results, either locally written or based on international media syndicate reports. There also was substantial concurrent coverage by local and national radio and television outlets, including the Cable News Network, ABC World News Tonight , and National Public Radio. A substantial fraction of these news stories may be attributable to press releases and media briefings prior to publication. However, the interest by television and print journalists in reporting the results of a peer-reviewed journal article to the general public was motivated by the recognition that describing the presence of PPCPs in water supplies would be of interest to the public. To better convey the results of the study published by Koplin et al. to the public, a separate general-interest fact sheet was published to summarize the important points of the study. Because PPCPs are commonly and widely used by individuals, there is likely a preexisting, personal identification with these compounds that does not occur for the wide range of other organic and inorganic contaminants whose presence in the environment has previously been described. This greater public “name recognition” makes itself known through the media to the regulatory and technical community and has prompted interest in sponsoring research that defines the composition and concentrations of PPCPs in potential sources and their fate and effects following relase into the environment. Independent of the drivers that potentially fuel the interest in studies of PPCPs, it is clear that PPCP research has grown beyond surface-water studies to examine issues such as: • Presence in other matrices, such as groundwater, landfill leachates, sediments, and biosolids. • Environmental transport and fate in surface water, groundwater, and soils amended with reclaimed water or biosolids. • PPCP source elucidation, such as wastewater treatment plant (WWTP) effluents, confined animal feeding operations (CAFOs), and aquaculture. • Removal during wastewater and drinking-water treatment. • Effects on aquatic ecosystems, terrestrial ecosystems, and human health. The chapters in this book provide an extensive examination of current environmental pharmaceutical research and are divided into three sections: “Occurrence and Analysis of Pharmaceuticals in the Environment,” “Environment Fate and Transformations of Veterinary Pharmaceuticals,” and “treatment of Pharmaceuticals in Drinking Water and Wastewater.” The purpose of this introductory overview chapter is to outline current (2004-2006) knowledge about the presence and concentration of PPCPs as described in the published literature. Previous reviews should be consulted for discussions on pre-2004 publications. Those reviews will provide the reader with a comprehensive introduction to the topic of PPCPs in the environment. This chapter describes the sources of PPCPs and other organic contaminants often associated with human wastewater into the environment, the range of concentrations present in various environmental compartments, and the potential routes of removal/sequestration. An overview of the sources and fate of veterinary pharmaceuticals will be discussed in Chapter 5, “Fate and Transport of Veterinary Medicines in the Soil Environment.”

Book chapter↗

USGS2015

Can orchards help connect Mediterranean ecosystems? Animal movement data alter conservation priorities

As natural habitats become fragmented by human activities, animals must increasingly move through human-dominated systems, particularly agricultural landscapes. Mapping areas important for animal movement has therefore become a key part of conservation planning. Models of landscape connectivity are often parameterized using expert opinion and seldom distinguish between the risks and barriers presented by different crop types. Recent research, however, suggests different crop types, such as row crops and orchards, differ in the degree to which they facilitate or impede species movements. Like many mammalian carnivores, bobcats ( Lynx rufus ) are sensitive to fragmentation and loss of connectivity between habitat patches. We investigated how distinguishing between different agricultural land covers might change conclusions about the relative conservation importance of different land uses in a Mediterranean ecosystem. Bobcats moved relatively quickly in row crops but relatively slowly in orchards, at rates similar to those in natural habitats of woodlands and scrub. We found that parameterizing a connectivity model using empirical data on bobcat movements in agricultural lands and other land covers, instead of parameterizing the model using habitat suitability indices based on expert opinion, altered locations of predicted animal movement routes. These results emphasize that differentiating between types of agriculture can alter conservation planning outcomes.

California↗

USGS2007

Evaluating estimators for numbers of females with cubs-of-the-year in the Yellowstone grizzly bear population

Current management of the grizzly bear ( Ursus arctos ) population in Yellowstone National Park and surrounding areas requires annual estimation of the number of adult female bears with cubs-of-the-year. We examined the performance of nine estimators of population size via simulation. Data were simulated using two methods for different combinations of population size, sample size, and coefficient of variation of individual sighting probabilities. We show that the coefficient of variation does not, by itself, adequately describe the effects of capture heterogeneity, because two different distributions of capture probabilities can have the same coefficient of variation. All estimators produced biased estimates of population size with bias decreasing as effort increased. Based on the simulation results we recommend the Chao estimator for model M h be used to estimate the number of female bears with cubs of the year; however, the estimator of Chao and Shen may also be useful depending on the goals of the research.

Wyoming↗

USGS2014

Mycotoxins: diffuse and point source contributions of natural contaminants of emerging concern to streams

To determine the prevalence of mycotoxins in streams, 116 water samples from 32 streams and three wastewater treatment plant effluents were collected in 2010 providing the broadest investigation on the spatial and temporal occurrence of mycotoxins in streams conducted in the United States to date. Out of the 33 target mycotoxins measured, nine were detected at least once during this study. The detections of mycotoxins were nearly ubiquitous during this study even though the basin size spanned four orders of magnitude. At least one mycotoxin was detected in 94% of the 116 samples collected. Deoxynivalenol was the most frequently detected mycotoxin (77%), followed by nivalenol (59%), beauvericin (43%), zearalenone (26%), β-zearalenol (20%), 3-acetyl-deoxynivalenol (16%), α-zearalenol (10%), diacetoxyscirpenol (5%), and verrucarin A (1%). In addition, one or more of the three known estrogenic compounds (i.e. zearalenone, α-zearalenol, and β-zearalenol) were detected in 43% of the samples, with maximum concentrations substantially higher than observed in previous research. While concentrations were generally low (i.e. < 50 ng/L) during this study, concentrations exceeding 1000 ng/L were measured during spring snowmelt conditions in agricultural settings and in wastewater treatment plant effluent. Results of this study suggest that both diffuse (e.g. release from infected plants and manure applications from exposed livestock) and point (e.g. wastewater treatment plants and food processing plants) sources are important environmental pathways for mycotoxin transport to streams. The ecotoxicological impacts from the long-term, low-level exposures to mycotoxins alone or in combination with complex chemical mixtures are unknown

Science of the Total Environment↗

USGS2011

Water-quality requirements, tolerances, and preferences of pallid sturgeon Scaphirhynchus albus in the lower Missouri River

Although numerous studies have been completed on pallid sturgeon populations and behavior, few have addressed the potential for water-quality characteristics to limit recruitment and population success of pallid sturgeon. Literature on sturgeon and water-quality data indicates recruitment of pallid sturgeon may be limited by several water-quality characteristics of the lower Missouri River including: High summer water temperatures in excess of 30 degrees Celsius, which likely are stressful to pallid sturgeon, Turbidities that are more than an order of magnitude less than the unaltered Missouri River and may no longer provide adequate cover for egg, larval, and young pallid sturgeon or for older pallid sturgeon attempting to capture prey, Dissolved oxygen that decreases to concentrations less than 2 milligrams per liter during some river rises in the late spring and summer, Food webs altered by increased light availability and hypereutrophic conditions caused by or enhanced by impoundment, bank stabilization, nonnative species, and decreased allocthanous material from the basin, Bioaccumulative contaminants, including polychlorinated biphenyls, chlordane, dichlorodiphenyltrichloroethane (DDT) and its metabolites, mercury, and synergistic contaminant cocktails that are particularly damaging to long-lived fish, and Other contaminants such as agricultural chemicals (particularly atrazine) and organic wastewater compounds that can disrupt endocrine systems of fish and limit reproduction at extremely low concentrations. Additional research could be used to characterize and quantify the requirements, tolerance, and preferences of pallid sturgeon to these water-quality characteristics, especially during the egg and larval life stages. Enhancements to existing water-sampling programs are needed to quantify the exposure of pallid sturgeon to many of these water-quality stressors.

Missouri River↗

USGS2026

Stream health shows indirect and threshold responses to implementation of agricultural conservation practices

Many agricultural conservation practices (hereafter conservation practices) are intended to protect streams from the deleterious effects of agriculture, but desired effects of their implementation are not always realized. Understanding the pathways through which conservation practices influence stream health can guide future implementation. Our goal was to quantify how conservation practices influence stream health in pastureland watersheds. We asked 4 research questions: R1) What are the effects of land use and conservation practices on instream conditions? R2) What are the effects of instream conditions on biota? R3) What are the relative effects of land use, conservation practices, and instream conditions on biota? R4) How do conservation practice density (no./ha) and agricultural land use interact to influence stream health? We collected data on water quality (total suspended solids, total N, total P, and Escherichia coli bacteria), instream habitat (substrate embeddedness and bank stability), and macroinvertebrate communities from 31 sites in the upper Tennessee River basin of southwest Virginia, USA. The sites collectively represented spatial analytical gradients of agricultural land use and density of conservation practices, with the dominant practices including prescribed grazing, brush management, and fencing. We found that conservation practice implementation was indirectly related to biotic assemblages through changes in water quality and habitat, but practice density in the study area was not associated with instream conditions that supported biotic communities representative of reference conditions. Further improving instream habitat conditions may require innovative conservation practices, targeted placement of practices in critical source areas of pollutants, or higher densities of practices.

Virginia↗

USGS2011

Carbon gas fluxes in re-established wetlands on organic soils differ relative to plant community and hydrology

We measured CO 2 and CH 4 fluxes for 6 years following permanent flooding of an agriculturally managed organic soil at two water depths (~25 and ~55 cm standing water) in the Sacramento–San Joaquin Delta, California, as part of research studying C dynamics in re-established wetlands. Flooding rapidly reduced gaseous C losses, and radiocarbon data showed that this, in part, was due to reduced oxidation of "old" C preserved in the organic soils. Both CO 2 and CH 4 emissions from the water surface increased during the first few growing seasons, concomitant with emergent marsh establishment, and thereafter appeared to stabilize according to plant communities. Areas of emergent marsh vegetation in the shallower wetland had greater net CO 2 influx (-485 mg Cm -1 h -1 ), and lower CH 4 emissions (11.5 mg Cm -2 h -1 ), than in the deeper wetland (-381 and 14.1 mg Cm -2 h -1 , respectively). Areas with submerged and floating vegetation in the deeper wetland had CH 4 emissions similar to emergent vegetation (11.9 and 12.6 mg Cm -2 h -1 , respectively), despite lower net CO 2 influx (-102 gC m -2 h -1 ). Measurements of plant moderated net CO 2 influx and CH 4 efflux indicated greatest potential reduction of greenhouse gases in the more shallowly flooded wetland.

California↗

USGS2020

Aeolian remobilisation of volcanic ash: Outcomes of a workshop in the Argentinian Patagonia

During explosive volcanic eruptions, large quantities of tephra can be dispersed and deposited over wide areas. Following deposition, subsequent aeolian remobilisation of ash can potentially exacerbate primary impacts on timescales of months to millennia. Recent ash remobilisation events (e.g., following eruptions of Cordón Caulle 2011; Chile, and Eyjafjallajökull 2010, Iceland) have highlighted this to be a recurring phenomenon with consequences for human health, economic sectors, and critical infrastructure. Consequently, scientists from observatories and Volcanic Ash Advisory Centers (VAACs), as well as researchers from fields including volcanology, aeolian processes and soil sciences, convened at the San Carlos de Bariloche headquarters of the Argentinian National Institute of Agricultural Technology to discuss the “state of the art” for field studies of remobilised deposits as well as monitoring, modeling and understanding ash remobilisation. In this article, we identify practices for field characterisation of deposits and active processes, including mapping, particle characterisation and sediment traps. Furthermore, since forecast models currently rely on poorly-constrained dust emission schemes, we call for laboratory and field measurements to better parameterise the flux of volcanic ash as a function of friction velocity. While source area location and extent are currently the primary inputs for dispersion models, once emission schemes become more sophisticated and better constrained, other parameters will also become important (e.g., source material volume and properties, effective precipitation, type and distribution of vegetation cover, friction velocity). Thus, aeolian ash remobilisation hazard and associated impact assessment require systematic monitoring, including the development of a regularly-updated spatial database of resuspension source areas.

Frontiers in Earth Science↗

USGS1963

Publications on fish parasites and diseases, 330 B.C.-A.D

These references were collected in 1924, but until now this collection has been available only in manuscript form. Because of the current increased interest in this field, this bibliography is being issued to make it more generally accessible. They include the earliest known references to fish parasites (330 B.C.) as well as a nearly complete collection up to 1924. In some instances only one or two works of a more prolific researcher are cited, therefore it is recommended that the student use the Index-Catalogue of Medical and Veterinary Zoology (U. S. Department of Agriculture) freely. For more current work consult the following, of which Dogiel et al.(1958), Hoffman and Sindermann (1962), Schaperclaus (1954), and Snieszko et aL(in press) have extensive bibliographies:

Special Scientific Report - Fisheries↗

USGS2024

The LTAR cropland Common Experiment at Lower Chesapeake Bay

The Lower Chesapeake Bay (LCB) Long-Term Agroecosystem Research (LTAR) Common Experiment (CE) located in Beltsville, MD, focuses on research of concern to producers of the major regional crops, which are corn ( Zea mays L.), soybean [ Glycine max (L.) Merr.], wheat ( Triticum aestivum L.), and various forage species. Livestock production in the region includes broiler and laying chickens ( Gallus gallus domesticus L.) and dairy and beef cattle ( Bos taurus L.). The LCB region is among the most heavily populated in the United States. Urban development pressure is high for both farms and natural areas. The need to restore Chesapeake Bay water quality is a major influence on regional agricultural practices. Conservation practices such as cover cropping, no-till agriculture, and nutrient management planning are more common in the region compared to nationally. However, farmers still face management challenges implementing practices that address water quality and the rise of herbicide-resistant weeds. Researchers at the LCB site recognize the need to protect the Chesapeake and Delaware Bays and maintain farmer profitability. The LCB CE compares a 3-year crop rotation system featuring alternative crop management (cover crop intensification, crop rotation diversification, and integrated weed management [IWM]) with a prevailing 2-year system (no cover crops and no IWM), both under continuous no-tillage, to identify the optimal balance to promote the sustainability of regional cropping systems. The LTAR LCB site provides data-driven tools and solutions to support farmers in the mid-Atlantic region.

Delaware, Maryland, New Jersey, Pennsylvania, Virg↗

USGS2017

Enhancing wind erosion monitoring and assessment for U.S. rangelands

On the Ground Wind erosion is a major resource concern for rangeland managers because it can impact soil health, ecosystem structure and function, hydrologic processes, agricultural production, and air quality. Despite its significance, little is known about which landscapes are eroding, by how much, and when. The National Wind Erosion Research Network was established in 2014 to develop tools for monitoring and assessing wind erosion and dust emissions across the United States. The Network, currently consisting of 13 sites, creates opportunities to enhance existing rangeland soil, vegetation, and air quality monitoring programs. Decision-support tools developed by the Network will improve the prediction and management of wind erosion across rangeland ecosystems.

Rangelands↗

USGS1976

Summary appraisals of the nation's ground-water resources – California region

Most people in the California Region live in a semiarid or arid climate, with precipitation less than the potential evapotranspiration- environments of perennial water deficiency. The deficiency becomes most onerous during the characteristically rainless summers and during recurrent droughts that may continue for 10--20 years. However, water from winter rain and snow can be stored for use during the dry summer months, and water stored during a wet climatic period can be used in a succeeding dry period; moreover, perennial deficiency can be overcome by bringing water from areas of perennial surplus. Ground-water reservoirs have especial significance in arid and semiarid regions as repositories where water is stored or can be stored with minimum loss by evaporation. Nearly all the ground-water reservoirs of the California Region are in alluvial sediments of valleys and plains that flank the mountain ranges. The largest, underlying the vast Central Valley, occupies 10 percent of the area of the region, has an estimated usable capacity exceeding 100 million acre-feet (125 cubic kilometres), and has an annual pumpage from wells of about 13 million acre-feet (16 cubic kilometres). Another 10 percent of the region is occupied by 55 developed ground-water reservoirs that are widely distributed; aggregate annual pumpage from them is about 3 1/2 million acre-feet (4 cubic kilometres). In the southeastern desert about 60 ground-water reservoirs occupy still another 10 percent of the region; these have been explored only enough to show that most have some usable water, but current use is negligible. In northeastern California and adjacent Oregon and Nevada, ground-water reservoirs are identified only in valleys and lowlands where wells are feasible, but basaltic rocks of the Cascade Range and Modoc Plateau are excellent aquifers distributed over an area constituting about 15 percent of the region. In sum, slightly less than half the California Region is underlain by ground-water reservoirs, either in valley fill or in volcanic rocks, which can yield significant quantities of water to wells. The rest of the California Region includes the mountains, canyons, slopes, and foothills of the Sierra Nevada, Coast Ranges, and Basin Ranges, whose consolidated rocks and products of their weathering may be permeable locally but are not generally so. Here, the prevailing method of ground-water development is still mostly trial and error, and while in many places a well can yield enough water for a family, some families might have to do without amenities such as flush toilets and automatic washers. For more than half a century the California Region has led all others in North America in pumping of ground water as well as in the area, variety, yield, and export of crops irrigated by water from wells. It has led in the development and use of deep-well turbine pumps for large yield and in the drilling of water wells to great depths. At the same time, such developments have resulted in the elimination of artesian pressures that produced thousands of flowing wells in the 19th century and led to the wide distribution of "falling water tables." Also, California was first to induce encroachment of seawater into wells (in 1906); first to recognize subsidence of land caused by pumping from wells (in 1933), generating news about land sinking in San Jose, Long Beach, and along the Delta-Mendota and Friant-Kern Canals; and first to experience pollution of ground-water reservoirs by brines, chemicals, industrial wastes, and petroleum byproducts including gasoline. The region has led in research in several fields leading to solution of many of these problems. Ground-water problems developed rapidly after World War II with booming population, agriculture, industry, and water demand during several years of regionwide drought. Water levels in wells trended downward almost everywhere as a natural effect of the drought and at accelerated rates in areas of pumping for new enterprises or to supplement subnormal surface-water supplies. The declines in many pumping areas exceeded 100 feet (30 metres), and in some confined aquifers the potentiometric surface was drawn down more than 330 feet (100 metres). The depletion of ground-water storage has had "permanent" side effects, including subsidence of the land exceeding 10 feet (3 metres) in extensive areas, and seawater intrusion that ended the useful lives of many wells along the coast and as much as 6 miles (10 kilometres) inland. Some problems have been solved, but these solutions have at times created other problems. Many ground-water reservoirs have gone through one or more stages - exploration for productive aquifers, exploitation and development for use of the water, restriction to the perennial supply or "safe" yield, importation of surface water, artificial recharge of ground water, conjunctive use of surface and ground water, protection of water quality, and integrated management of use and disposal of water. This evolutionary sequence is unique for each reservoir, and so generalizations become difficult in a regional appraisal; also, the changes with time are significant and varied, and knowledge of prior events is a prerequisite in an appraisal of the resource in a specific year. As of 1970, water levels in many wells had risen significantly from the minimum levels of record reached during the 1960's or earlier; only in areas of new development and in desert areas of long-continued "mining" of nonreplenished water was ground-water storage still being depleted. Land subsidence has continued at diminishing rates and practically has come to a halt in some areas; invading seawater has been stopped or nudged back in most places where problems were significant. The current, favorable situation has been helped by climatic variations, from drought in 1945-52 and exceedingly dry years in 1959 and 1961 to above-normal precipitation in 1969 and 1970; but most of the serious problems have been solved by human efforts, including especially the implementation of the California Water Plan, transporting water from areas of perennial surplus to areas where it is used in lieu of ground water or for ground-water replenishment. All major urban areas now import water to supplement or replace the water pumped from wells. Extensive agricultural areas that formerly were irrigated solely by ground water now obtain some of their water from surface reservoirs and canals, especially in the Central Valley. With surface water available as an alternative supply, well owners can view their ground water with complacency. But complacency can lead to neglect and carelessness and consequent deterioration of the ground-water resource by pollution. Claiming heritage from the English Common Law, the existing California law grants to the landowner (riparian) and private enterprise (appropriator) rights to the water stored in ground-water reservoirs or discharged from them, including the base flow of streams. Ground-water development has been by private and local enterprise, and the California legislature has protected and encouraged local responsibility, control, and management of ground water. As to surface water, a constitutional amendment in 1928 limited riparian rights to the quantities of water that were "reasonably required for the beneficial use to be served." The surpluses have become public waters which are collected, stored, transported, and delivered under various contracts by Federal, State, and other agencies. The agencies have not stored water underground because of uncertainty as to their rights, but some local agencies have been encouraged with favorable pricing schedules to undertake the artificial recharge and management of ground-water reservoirs. Thus, conjunctive use of surface and ground water has become a matter of interagency negotiation. Of all the constraints on effective use of ground-water reservoirs, the most formidable may be the attitudes of people. Assurance of water supply is vital in areas of water deficiency, and Government has assumed increasing responsibility for the welfare of people in these areas. Unfortunately, when Government provides this assurance, most beneficiaries demand continued subsidy to the exclusion of perhaps cheaper private development. Indeed, as the water resources are presently segregated-with private rights predominant in ground water and public interest dominant in surface water-ground-water development has suffered for lack of public concern. The region has the scientific and technologic capability for effective use of groundwater reservoirs, as shown by the achievements and programs of several districts, but many districts are not organized or staffed for such comprehensive management and will need assistance and scientific expertise available from State and Federal agencies. Those agencies, in turn, may not have the scientific data that are essential to prevent haphazard activities and to enable programs to be organized for the most effective and attractive utilization of the water resources. In these days of increasing concern over pollution, existing data are generally inadequate to assess the natural deterioration of ground waters as a basis for defining pollution.

California↗