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At least 631 records · Page 35Linked to original sources

Potential effects of climate change on inland glacial lakes and implications for lake-dependent biota in Wisconsin: final report April 2013

The economic vitality and quality of life of many northern Wisconsin communities is closely associated with the ecological condition of the abundant water resources in the region. Climate change models predict warmer temperatures, changes to precipitation patterns, and increased evapotranspiration in the Great Lakes region. Recently (1950-2006), many regions of Wisconsin have experienced warming, and precipitation has generally increased except in far northern Wisconsin. Modeling conducted by the University of Wisconsin Nelson Environmental Institute Center for Climate Research predicts an increase in annual temperature by the middle of the 21st century of approximately 6° F statewide, and an increase in precipitation of 1”–2”. However, summer precipitation in the northern part of the state is expected to be less and winter precipitation will be greater. By the end of the 21st century, the magnitude of changes in temperature and precipitation are expected to intensify. Such climatic changes have altered, and would further alter hydrological, chemical, and physical properties of inland lakes. Lake-dependent wildlife sensitive to changes in water quality, are particularly susceptible to lake quality-associated habitat changes and are likely to suffer restrictions to current breeding distributions under some climate change scenarios. We have selected the common loon (Gavia immer) to serve as a sentinel lake-dependent piscivorous species to be used in the development of a template for linking primary lake-dependent biota endpoints (e.g., decline in productivity and/or breeding range contraction) to important lake quality indicators. In the current project, we evaluate how changes in freshwater habitat quality (specifically lake clarity) may impact common loon lake occupancy in Wisconsin under detailed climate-change scenarios. In addition, we employ simple land-use/land cover and habitat scenarios to illustrate the potential interaction of climate and land-use/land cover effects. The methods employed here provide a template for studies where integration of physical and biotic models is used to project future conditions under various climate and land use change scenarios. Findings presented here project the future conditions of lakes and loons within an important watershed in northern Wisconsin – of importance to water resource managers and state citizens alike.

Wisconsin↗

Reconnaissance survey for potential energy storage and carbon dioxide storage resources of petroleum reservoirs in western Europe

Energy producers and utilities use oil and gas reservoirs for gas storage to meet peak seasonal demand or to supplement intermittent energy production. These reservoirs are also suitable for the long-term storage of carbon dioxide (CO 2 ), a greenhouse gas. This study reports on a reconnaissance analysis of the potential magnitude of storage resources in 9424 known oil and gas reservoirs from 24 countries within highly industrialized western Europe. To standardize the storage resources of the oil and gas reservoirs, their volumetric capacity is expressed in terms of metric tons (mass) of CO 2 . Estimates of recoverable oil and gas at the surface are converted to subsurface volumes and then converted to the equivalent mass of CO 2 at reservoir conditions. The results indicate 36.7 gigatons of CO 2 could be stored, with oil reservoirs accounting for 32% of that total and natural gas reservoirs comprising the remaining 68%. About four-fifths of the reservoir storage resource is offshore, with about three-fourths of that offshore resource at water depths of 200 m or less. Most countries do not have the reservoir storage resources to store 15 years of CO 2 at 2017 emission levels. With few exceptions the bulk of the storage is offshore for countries that do have at least 15 years of storage. The expansion of natural gas storage for strategic purposes in abandoned onshore gas reservoirs is not expected to seriously impact CO 2 storage. The contribution of this analysis is the description of the spatial distribution of potential storage and physical accessibility.

Natural Resources Research↗

Lake Ontario: Food web dynamics in a changing ecosystem (1970-2000)

We examined stressors that have led to profound ecological changes in the Lake Ontario ecosystem and its fish community since 1970. The most notable changes have been reductions in phosphorus loading, invasion by Dreissena spp., fisheries management through stocking of exotic salmonids and control of sea lamprey ( Petromyzon marinus ), and fish harvest by anglers and double-crested cormorants ( Phalacrocorax auritus ). The response to these stressors has led to ( i ) declines in both algal photosynthesis and epilimnetic zooplankton production, ( ii ) decreases in alewife ( Alosa pseudoharengus ) abundance, ( iii ) declines in native Diporeia and lake whitefish ( Coregonus clupeaformis ), ( iv ) behavioral shifts in alewife spatial distribution benefitting native lake trout ( Salvelinus namaycush ), threespine stickleback ( Gasterosteus aculeatus ), and emerald shiner ( Notropis atherinoides ) populations, ( v ) dramatic increases in water clarity, ( vi ) predation impacts by cormorants on select fish species, and ( vii ) lake trout recruitment bottlenecks associated with alewife-induced thiamine deficiency. We expect stressor responses associated with anthropogenic forces like exotic species invasions and global climate warming to continue to impact the Lake Ontario ecosystem in the future and recommend continuous long-term ecological studies to enhance scientific understanding and management of this important resource.

Canadian Journal of Fisheries and Aquatic Sciences↗

Front Range Infrastructure Resources Project--Biological Resources

Riparian (streamside) vegetation communities are of interest in the context of the Front Range Infrastructure Resources Project (FRIRP) because they are often a focal point for conflicting societal demands. The cottonwoods and willows comprising these communities are structurally complex compared to the surrounding landscape and support diverse assemblages of mammals, birds, reptiles, and amphibians. However, riparian areas are also primary sites for water development, agriculture, grazing, sand and gravel mining, and recreation, each of which may limit other uses. Direct and indirect impacts of these activities have led to exploration of new opportunities and techniques for restoring disturbed riparian habitats and to greater concern for some of the scarce species that inhabit them.

Colorado, Wyoming↗

The importance of the Northeastern Gulf of Mexico to foraging loggerhead sea turtles

Identification of high-use foraging sites where imperiled sea turtles are resident remains a globally-recognized conservation priority. In the biodiverse Gulf of Mexico (GoM), recent telemetry studies highlighted post-nesting foraging sites for federally threatened loggerhead turtles (Caretta caretta). Our aim here was to discern loggerhead use of additional northern GoM regions that may serve as high-use foraging sites. Thus, we used satellite tracking and switching state-space modeling to show that the Big Bend region off the northwest Florida coast is a coastal foraging area that supports imperiled adult female loggerhead turtles tracked from different nesting subpopulations. From 2011 to 2016, we satellite-tagged 15 loggerheads that nested on four distinct beaches around the GoM: Dry Tortugas National Park, FL; Everglades National Park, FL; St. Joseph Peninsula, FL; and Gulf Shores, AL. Turtles arrived at their foraging ground in the Big Bend region between June and September and remained resident in their respective foraging sites for an average of 198 tracking days, where they established mean home ranges (95% kernel density estimate) 232.7 km2. Larger home ranges were in deeper water; 50% kernel density estimate centroid values were a mean 26.4 m deep and 52.7 km from shore. The Big Bend region provides a wide area of suitable year-round foraging habitat for loggerheads from at least 3 different nesting subpopulations. Understanding where and when threatened loggerheads forage and remain resident is key for designing both surveys of foraging resources and additional protection strategies that can impact population recovery trajectories for this imperiled species.

Florida↗

Quantification of aquifer properties with surface nuclear magnetic resonance in the Platte River valley, central Nebraska, using a novel inversion method

Surface nuclear magnetic resonance, a noninvasive geophysical method, measures a signal directly related to the amount of water in the subsurface. This allows for low-cost quantitative estimates of hydraulic parameters. In practice, however, additional factors influence the signal, complicating interpretation. The U.S. Geological Survey, in cooperation with the Central Platte Natural Resources District, evaluated whether hydraulic parameters derived from surface nuclear magnetic resonance data could provide valuable input into groundwater models used for evaluating water-management practices. Two calibration sites in Dawson County, Nebraska, were chosen based on previous detailed hydrogeologic and geophysical investigations. At both sites, surface nuclear magnetic resonance data were collected, and derived parameters were compared with results from four constant-discharge aquifer tests previously conducted at those same sites. Additionally, borehole electromagnetic-induction flowmeter data were analyzed as a less-expensive surrogate for traditional aquifer tests. Building on recent work, a novel surface nuclear magnetic resonance modeling and inversion method was developed that incorporates electrical conductivity and effects due to magnetic-field inhomogeneities, both of which can have a substantial impact on the data. After comparing surface nuclear magnetic resonance inversions at the two calibration sites, the nuclear magnetic-resonance-derived parameters were compared with previously performed aquifer tests in the Central Platte Natural Resources District. This comparison served as a blind test for the developed method. The nuclear magnetic-resonance-derived aquifer parameters were in agreement with results of aquifer tests where the environmental noise allowed data collection and the aquifer test zones overlapped with the surface nuclear magnetic resonance testing. In some cases, the previously performed aquifer tests were not designed fully to characterize the aquifer, and the surface nuclear magnetic resonance was able to provide missing data. In favorable locations, surface nuclear magnetic resonance is able to provide valuable noninvasive information about aquifer parameters and should be a useful tool for groundwater managers in Nebraska.

Nebraska↗

Consequences of declining snow accumulation for water balance of mid-latitude dry regions

Widespread documentation of positive winter temperature anomalies, declining snowpack and earlier snow melt in the Northern Hemisphere have raised concerns about the consequences for regional water resources as well as wildfire. A topic that has not been addressed with respect to declining snowpack is effects on ecosystem water balance. Changes in water balance dynamics will be particularly pronounced at low elevations of mid-latitude dry regions because these areas will be the first to be affected by declining snow as a result of rising temperatures. As a model system, we used simulation experiments to investigate big sagebrush ecosystems that dominate a large fraction of the semiarid western United States. Our results suggest that effects on future ecosystem water balance will increase along a climatic gradient from dry, warm and snow-poor to wet, cold and snow-rich. Beyond a threshold within this climatic gradient, predicted consequences for vegetation switched from no change to increasing transpiration. Responses were sensitive to uncertainties in climatic prediction; particularly, a shift of precipitation to the colder season could reduce impacts of a warmer and snow-poorer future, depending on the degree to which ecosystem phenology tracks precipitation changes. Our results suggest that big sagebrush and other similar semiarid ecosystems could decrease in viability or disappear in dry to medium areas and likely increase only in the snow-richest areas, i.e. higher elevations and higher latitudes. Unlike cold locations at high elevations or in the arctic, ecosystems at low elevations respond in a different and complex way to future conditions because of opposing effects of increasing water-limitation and a longer snow-free season. Outcomes of such nonlinear interactions for future ecosystems will likely include changes in plant composition and productivity, dynamics of water balance, and availability of water resources.

Global Change Biology↗

Divergent climate change effects on widespread dryland plant communities driven by climatic and ecohydrological gradients

Plant community response to climate change will be influenced by individual plant responses that emerge from competition for limiting resources that fluctuate through time and vary across space. Projecting these responses requires an approach that integrates environmental conditions and species interactions that result from future climatic variability. Dryland plant communities are being substantially affected by climate change because their structure and function are closely tied to precipitation and temperature, yet impacts vary substantially due to environmental heterogeneity, especially in topographically complex regions. Here, we quantified the effects of climate change on big sagebrush ( Artemisia tridentata Nutt.) plant communities that span 76 million ha in the western United States. We used an individual-based plant simulation model that represents intra- and inter-specific competition for water availability, which is represented by a process-based soil water balance model. For dominant plant functional types, we quantified changes in biomass and characterized agreement among 52 future climate scenarios. We then used a multivariate matching algorithm to generate fine-scale interpolated surfaces of functional type biomass for our study area. Results suggest geographically divergent responses of big sagebrush to climate change (changes in biomass of −20% to +27%), declines in perennial C 3 grass and perennial forb biomass in most sites, and widespread, consistent, and sometimes large increases in perennial C 4 grasses. The largest declines in big sagebrush, perennial C 3 grass and perennial forb biomass were simulated in warm, dry sites. In contrast, we simulated no change or increases in functional type biomass in cold, moist sites. There was high agreement among climate scenarios on climate change impacts to functional type biomass, except for big sagebrush. Collectively, these results suggest divergent responses to warming in moisture-limited versus temperature-limited sites and potential shifts in the relative importance of some of the dominant functional types that result from competition for limiting resources.

Global Change Biology↗

Salinity yield modeling of the Upper Colorado River Basin using 30-meter resolution soil maps and random forests

Salinity loading in the Upper Colorado River Basin (UCRB) costs local economies upwards of $300 million US dollars annually. Salinity source models have generally included coarse spatial data to represent non‐agriculture sources. We developed new predictive soil property and cover maps at 30 m resolution to improve source representation in salinity modeling. Salinity loading erosion risk indices were also created based on soil properties, remotely sensed bare ground exposure, and topographic factors to examine potential surface soil erosion drivers. These new maps and data from previous SPARROW models were related to recently updated records of salinity at 309 stream gauges in the UCRB using random forest regressions. Resulting salinity yield predictions indicate more diffuse salinity sources, with slightly higher yields in more arid portions of the UCRB, and less overall load coming from irrigated agricultural sources. Model simulations still indicate irrigation to be the major human source of salinity (661,000 Mg, or 12%), but also suggest that 75,000 Mg (1.4%) of annual salinity in the UCRB is coming from areas with excessive exposed bare ground in high elevation mountain areas. Model inputs allow for field scale screening of locations that could be targeted for salinity control projects. Results confirm recent studies indicating limited surface erosional influence on salinity loading in UCRB surface waters, but impacts of monsoonal runoff events are still not fully understood, particularly in drylands. The study highlights the utility of new predictive soil maps and machine learning for environmental modeling.

Arizona, Colorado, New Mexico, Utah, Wyoming↗

Characterizing physical properties of streambed interface sediments using in situ complex electrical conductivity measurements

Streambed sediment physical properties such as surface area, are difficult to quantify in situ but exert a high‐level control on a wide range of biogeochemical processes and sorption of contaminants. We introduce the use of complex electrical conductivity (CC) methods (also known as spectral induced polarization (SIP)) that measure both real and imaginary conductivity to non‐invasively and efficiently characterize shallow streambed sediments. We explore the method through synthetic modeling, laboratory, and field measurements to demonstrate the sensitivity of imaginary conductivity to sediment surface area, controlled in part by fine‐grained iron oxides produced by anoxic groundwater discharge. Laboratory measurements verify expected relationships between CC parameters and sediment properties. Synthetic modeling using a 1D analytical model illustrates the influence of water layer depth and conductivity on the field CC measurements made at the streambed‐stream water interface. Specifically, the inverted sediment imaginary conductivity is less impacted by uncertainty in the water layer depth and conductivity relative to the real conductivity and phase shift. Field CC measurements along a landfill‐impacted river reveal discrete streambed zones with enhanced bulk surface area generally corresponding to anoxic groundwater discharges zones with high concentrations of fine‐grained iron oxide precipitates.

Water Resources Research↗

Effects of off-road vehicle use on the hydrology and landscape of arid environments in central and southern California

Two widely separated sites in California used for motorcycle hill-climbing were studied to evaluate the impact on the landscape and hydrology. At Panoche Hills in central California, an area formerly used by motorcycles together with an adjacent unused area were monitored from 1971 to 1975. Observations in both areas included measurements of precipitation, runoff, soil moisture, soil bulk density, plant cover, and erosion surveys. At Dove Spring Canyon in southern California erosion was measured on a site that is currently being used for motorcycle hill-climbing. At the Panoche Hills site, the area used by motorcycles produced about eight times as much runoff as the unused area. Similarly, sediment yield from the used areas was 857 cubic meters/sq km, while the quantity of sediment from the unused area was not measurable by standard methods. At the Dove Spring Canyon site, which is still being used for hill-climbing, erosion surveys show that degradation in trails has been as much as 0.3 m in the period 1973-75. Compaction of soils and reduction of permeability appears to be the most serious hydrologic impact of motorcycle use at Panoche Hills. Increased bulk density of soils reduces depth of moisture penetration which deprives plants of moisture needed for growth. (Woodard-USGS)

California↗

South Atlantic summary report 2: A revision of Outer Continental Shelf oil and gas activities in the South Atlantic (U.S.) and their onshore impacts, a summary report, July 1980

The search for oil and gas on the Outer Continental Shelf (OCS) in the South Atlantic Region began in 1960, when geophysical surveys of the area were initiated. In 1977, a Continental Offshore Stratigraphic Test (COST) well was drilled in the Southeast Georgia Embayment. In March 1978, the first lease sale, Sale 43, was held, resulting in the leasing of 43 tracts. Approximately a year later, in May 1979, the first exploratory drilling began, and by February 1980, six exploratory wells had been drilled by four companies. Hydrocarbons were not found in any of these wells. Lease Sale 56, the second lease sale in the South Atlantic Region, was held in August 1981. The sale resulted in the leasing of 47 tracts. Most of the leased tracts are in deep water along the Continental Slope off North Carolina. To date, no drilling has occurred on these tracts, but it is likely that two wells will be drilled or will be in the process of being drilled by the end of 1982. Reoffering Sale RS-2 is scheduled for July 1982, and it will include tracts offered in Lease Sale 56 that were not awarded leases. Lease Sale 78 is scheduled to be held in July 1983. The most recent (March 1982) estimates of risked resources for leased lands in the South Atlantic OCS are 27 million barrels of oil and 120 billion cubic feet of gas. To date, onshore impacts resulting from OCS exploration have been minimal, and they were associated with Lease Sale 43 exploratory activities. Tenneco, using existing facilities, established a support base in Savannah, Georgia; Getty, Transco, and Exxon used a support base established for them by the city of Brunswick, Georgia. The port at Morehead City, North Carolina, is expected to provide the onshore facilities for exploration in the near future on Lease Sale 56 tracts. Arrangements for the use of these facilities are currently being negotiated. In June 1981, the South Atlantic Regional Technical Working Group prepared a Regional Transportation Management Plan for the South Atlantic OCS. The plan is principally an integration of regulatory frameworks, policies, and plans that are applicable to pipeline siting from each of the South Atlantic coastal States and Federal agencies with jurisdiction in the area.

Outer Continental Shelf, South Atlantic↗

Migration efficiency sustains connectivity across agroecological networks supporting sandhill crane migration

Preserving avian flyway connectivity has long been challenged by our capacity to meaningfully quantify continental habitat dynamics and bird movements at temporal and spatial scales underlying long-distance migrations. Waterbirds migrating hundreds or thousands of kilometers depend on networks of wetland stopover sites to rest and refuel. Entire populations may rely on discrete wetland habitats, particularly in arid landscapes where the loss of limited stopover options can have disproportionately high impacts on migratory cost. Here, we examine flyway connectivity in water-limited ecosystems of western North America using 108 GPS tagged greater sandhill cranes. Bird movements were used to reconstruct wetland stopover networks across three geographically unique sub-populations spanning 12 US-Mexican states and Canadian provinces. Networks were monitored with remote sensing to identify long-term (1988-2019) trends in wetland and agricultural resources supporting migration and evaluated using network theory and centrality metrics as a measure of stopover site importance to flyway connectivity. Sandhill crane space-use was analyzed in stopover locations to identify important ownership and landscape factors structuring bird distributions. Migratory efficiency was the primary mechanism underpinning network function. A small number of key stopover sites important to minimizing movement cost between summering and wintering locations were essential to preserving flyway connectivity. Localized efficiencies were apparent in stopover landscapes given prioritization of space-use by birds where the proximity of agricultural food resources and flooded wetlands minimized daily movements. Model depictions showing wetland declines from 16-18% likely reflect a new normal in landscape drying that could decouple agriculture-waterbird relationships as water scarcity intensifies. Sustaining network resilience will require conservation strategies to balance water allocations preserving agricultural and wetlands on private lands that accounted for 67-96% of habitat use. Study outcomes provide new perspectives of agroecological relationships supporting continental waterbird migration needed to prioritize conservation of landscapes vital to maintaining flyway connectivity.

western North America↗

Simulated impacts of artificial groundwater recharge and discharge of the source area and source volume of an Atlantic Coastal Plain Stream, Delaware, USA

A numerical groundwater-flow model was used to characterize the source area and volume of Phillips Branch, a baseflow-dominated stream incising a highly permeable unconfined aquifer on the low relief Delmarva Peninsula, USA. Particle-tracking analyses indicate that the source area (5.51 km 2 ) is ~20% smaller than the topographically defined watershed (6.85 km 2 ), and recharge entering ~37% of the surface watershed does not discharge to Phillips Branch. Groundwater residence time within the source volume ranges from a few days to almost 100 years, with 95% of the volume "flushing" within 50 years. Artificial discharge from groundwater pumping alters the shape of the source area and reduces baseflow due to the interception of stream flow paths, but has limited impacts on the residence time of groundwater discharged as baseflow. In contrast, artificial recharge from land-based wastewater disposal substantially reduces the source area, lowers the range in residence time due to the elimination of older flow paths to the stream, and leads to increased discharge to adjacent surface-water bodies. This research suggests that, in this and similar hydrogeologic settings, the "watershed" approach to water-resource management may be limited, particularly where anthropogenic stresses alter the transport of soluble contaminants through highly permeable unconfined aquifers.

Delaware↗

Deep-sea coral research and technology program: Alaska deep-sea coral and sponge initiative final report

Deep-sea coral and sponge ecosystems are widespread throughout most of Alaska’s marine waters. In some places, such as the central and western Aleutian Islands, deep-sea coral and sponge resources can be extremely diverse and may rank among the most abundant deep-sea coral and sponge communities in the world. Many different species of fishes and invertebrates are associated with deep-sea coral and sponge communities in Alaska. Because of their biology, these benthic invertebrates are potentially impacted by climate change and ocean acidification. Deepsea coral and sponge ecosystems are also vulnerable to the effects of commercial fishing activities. Because of the size and scope of Alaska’s continental shelf and slope, the vast majority of the area has not been visually surveyed for deep-sea corals and sponges. NOAA’s Deep Sea Coral Research and Technology Program (DSCRTP) sponsored a field research program in the Alaska region between 2012–2015, referred to hereafter as the Alaska Initiative. The priorities for Alaska were derived from ongoing data needs and objectives identified by the DSCRTP, the North Pacific Fishery Management Council (NPFMC), and Essential Fish Habitat-Environmental Impact Statement (EFH-EIS) process. This report presents the results of 15 projects conducted using DSCRTP funds from 2012-2015. Three of the projects conducted as part of the Alaska deep-sea coral and sponge initiative included dedicated at-sea cruises and fieldwork spread across multiple years. These projects were the eastern Gulf of Alaska Primnoa pacifica study, the Aleutian Islands mapping study, and the Gulf of Alaska fish productivity study. In all, there were nine separate research cruises carried out with a total of 109 at-sea days conducting research. The remaining projects either used data and samples collected by the three major fieldwork projects or were piggy-backed onto existing research programs at the Alaska Fisheries Science Center (AFSC).

NOAA Technical Memorandum↗

Hydrologic analyses in support of the Navajo Generating Station–Kayenta Mine Complex environmental impact statement

Introduction The U.S. Department of Interior’s Bureau of Reclamation, Lower Colorado Region (Reclamation) is preparing an environmental impact statement (EIS) for the Navajo Generating Station-Kayenta Mine Complex Project (NGS-KMC Project). The proposed project involves various Federal approvals that would facilitate continued operation of the Navajo Generating Station (NGS) from December 23, 2019 through 2044, and continued operation of the Kayenta Mine and support facilities (collectively called the Kayenta Mine Complex, or KMC) to supply coal to the NGS for this operational period. The EIS will consider several project alternatives that are likely to produce different effects on the Navajo (N) aquifer; the N aquifer is the principal water resource in the Black Mesa area used by the Navajo Nation, Hopi Tribe, and Peabody Western Coal Company (PWCC). The N aquifer is composed of three hydraulically connected formations—the Navajo Sandstone, the Kayenta Formation, and the Lukachukai Member of the Wingate Sandstone—that function as a single aquifer. The N aquifer is confined under most of Black Mesa, and the overlying stratigraphy limits recharge to this part of the aquifer. The N aquifer is unconfined in areas surrounding Black Mesa, and most recharge occurs where the Navajo Sandstone is exposed in the area near Shonto, Arizona. Overlying the N aquifer is the D aquifer, which includes the Dakota Sandstone, Morrison Formation, Entrada Sandstone, and Carmel Formation. The aquifer is named for the Dakota Sandstone, which is the primary water-bearing unit. The NGS is located near Page, Arizona on the Navajo Nation. The KMC, which delivers coal to NGS by way of a dedicated electric railroad, is located approximately 83 miles southeast of NGS (about 125 miles northeast of Flagstaff, Arizona). The Kayenta Mine permit area is located on about 44,073 acres of land leased within the boundaries of the Hopi and Navajo Indian Reservations. KMC has been conducting mining and reclamation operations within the Kayenta Mine permit boundary since 1973. The KMC part of the proposed project requires approval by the Office of Surface Mining (OSM) of a significant revision of the mine’s permit to operate in accordance with the Surface Mine Control and Reclamation Act (Public Law 95-87, 91 Stat. 445 [30 U.S.C. 1201 et seq. ]) . The revision will identify coal resource areas that may be used to continue extracting coal at the present rate of approximately 8.2 million tons per year. The Kayenta Mine Complex uses water pumped from the D and N aquifers beneath PWCC’s leasehold to support mining and reclamation activities. Prior to 2006, water from the PWCC well field also was used to transport coal by way of a coal-slurry pipeline to the now-closed Mohave Generating Station. Water usage at the leasehold was approximately 4,100 acre-feet per year (acre-ft/yr) during the period the pipeline was in use, and declined to an average 1,255 acre-ft/yr from 2006 to 2011. The Probable Hydrologic Consequences (PHC) section of the mining and reclamation permit must be modified to project the consequences of extended water use by the mine for the duration of the KMC part of the project, including a post-mining reclamation period. Since 1971, the U.S. Geological Survey (USGS) has conducted the Black Mesa Monitoring Program, which consists of monitoring water levels and water quality in the N aquifer, compiling information on water use by PWCC and tribal communities, maintaining several stream-gaging stations, measuring discharge at selected springs, conducting special studies, and reporting findings. These data are useful in evaluating the effects on the N aquifer from PWCC and community pumping, and the effects of variable precipitation. The EIS will assess the impacts of continued pumping on the N aquifer, including changes in storage, water quality, and effects on spring and baseflow discharge, by proposed mining through 2044, and during the reclamation process to 2057. Several groundwater models exist for the area and Reclamation concluded it would conduct a peer review of the groundwater flow model that will be used to assess the direct, reasonably foreseeable indirect, and cumulative effects of future groundwater withdrawals on the D and N aquifers in the Black Mesa area. Reclamation made this determination because of the level of controversy around the effects of continued water use and the comments received from the 2014 draft EIS scoping meetings. Reclamation requested assistance from the USGS in evaluating existing groundwater flow models of the Black Mesa Basin that can be used to predict the effects of different project alternatives on the D and N aquifers.

Arizona↗

Hydrologic analysis of the proposed Badger-Beaver Creeks artificial-recharge project: Morgan County, Colorado

A hydrologic analysis of the proposed Badger-Beaver Creeks artificial-recharge project in Morgan County, Colo., was made with the aid of three digital computer models: A canal-distribution model, a ground-water flow model, and a stream-aquifer model. Statistical summaries of probable diversions from the South Platte River based on a 27-year period of historical flows indicate that an average-annual diversion of 96,000 acre-feet and a median-annual diversion of 43,000 acre-feet would be available. Diversions would sustain water in ponds for waterfowl habitat for an average of about five months per year, with a miximum pond surface area of about 300 acres with the median diversions and a maximum pond surface area of about 1,250 acres at least one-half of the years with the historic diversions. If the annual diversion were 43,000 acre-feet, recharge to the two alluvial aquifers would raise water levels sufficiently to create flowing streams in the channels of Beaver and Badger Creeks while allowing an increase in current ground-water pumping. The only area of significant waterlogging would be along the proposed delivery canal on the west edge of Badger Creek valley. If the total water available were diverted, the aquifer system could not transmit the water fast enough to the irrigation areas to avoid considerable waterlogging in the recharge areas. The impact of the proposed project on the South Platte River basin would be minimal once the ground-water system attained steady-state conditions, but that may take decades with a uniform diversion of the 43,000 acre-feet annually.

Colorado↗

Ecohydrology and Its Relation to Integrated Groundwater Management

In the twentieth century, groundwater characterization focused primarily on easily measured hydraulic metrics of water storage and flows. Twenty-first century concepts of groundwater availability, however, encompass other factors having societal value, such as ecological well-being. Effective ecohydrological science is a nexus of fundamental understanding derived from two scientific disciplines: (1) ecology, where scale, thresholds, feedbacks and tipping points for societal questions form the basis for the ecologic characterization, and (2) hydrology, where the characteristics, magnitude, and timing of water flows are characterized for a defined system of interest. In addition to ecohydrology itself, integrated groundwater management requires input from resource managers to understand which areas of the vast world of ecohydrology are important for decision making. Expectations of acceptable uncertainty, or even what ecohydrological outputs have utility, are often not well articulated within societal decision making frameworks, or within the science community itself. Similarly, “acceptable levels of impact” are difficult to define. Three examples are given to demonstrate the use of ecohydrological considerations for long-term sustainability of groundwater resources and their related ecosystem function. Such examples illustrate the importance of accommodating ecohydrogeological aspects into integrated groundwater management of the twenty-first century, regardless of society, climate, or setting.

Book chapter↗