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At least 937 records · Page 52Linked to original sources

USGS2014

Estuarine monitoring programs in the Albemarle Sound study area, North Carolina

Albemarle Sound was selected in 2012 as one of the two demonstration sites in the Nation to test and improve the design of the National Water Quality Monitoring Council’s National Monitoring Network (NMN) for U.S. Coastal Waters and their tributaries. The goal of the NMN for U.S. coastal waters and tributaries is to provide information about the health of our oceans and coastal ecosystems and inland influences on coastal waters for improved resource management. The NMN is an integrated, multidisciplinary, and multiorganizational program using multiple sources of data and information to augment current monitoring programs. The purpose of this report is to identify major natural resource management issues for the region, provide information on current monitoring activities occurring within the Albemarle Sound study area, determine how the current monitoring network fits into the design of the NMN, and determine what additional monitoring data are needed to address these issues. In order to address these questions, a shapefile and data table were created to document monitoring and research programs in the Albemarle Sound study area with an emphasis on current monitoring programs within the region. This database was queried to determine monitoring gaps that existed in the Albemarle Sound by comparing current monitoring programs with the design indicated by the NMN. The report uses this information to provide recommendations on how monitoring could be improved in the Albemarle Sound study area.

North Carolina↗

USGS1998

Geology, geochemistry, geophysics, mineral occurrences, and mineral resource assessment for the Commonwealth of Puerto Rico

The Commonwealth of Puerto Rico has been investigated over a very long period of time by earth scientists from many disciplines and with diverse objectives in the studies. This publication attempts to apply much of the geologic, geochemical, geophysical, and mineral occurrence information to a single objective focused on producing a mineral resource assessment for the Commonwealth of Puerto Rico. However, the value of this publication lies not within the results of the mineral resource assessment nor within the interactive PDF files which can be viewed on the screen, but within the geologic, geochemical, geophysical, and mineral occurrence digital map coverages and databases which can be used for their own unique applications. The mineral resource assessment of Puerto Rico represents compilation of several decades of mineral investigations and studies. These investigations have been the joint efforts of the U.S. Geological Survey, the Puerto Rico Department of Natural Resources, and the University of Puerto Rico. This report contains not only the mineral-resource assessment, but also much of the scientific evidence upon which the assessment was based.

Puerto Rico↗

USGS2013

The 3D Elevation Program: summary for Alabama

Elevation data are essential to a broad range of applications, including forest resources management, wildlife and habitat management, national security, recreation, and many others. For the State of Alabama, elevation data are critical for flood risk management; infrastructure and construction management; wildfire management, planning, and response; natural resources conservation; geologic resource assessment and hazards mitigation; and other business uses. Today, high-density light detection and ranging (lidar) data are the primary sources for deriving elevation models and other datasets. Federal, State, and local agencies work in partnership to (1) replace data that are older and of lower quality and (2) provide coverage where publicly accessible data do not exist. A joint goal of State and Federal partners is to acquire consistent, statewide coverage to support existing and emerging applications enabled by lidar data. The National Enhanced Elevation Assessment evaluated multiple elevation data acquisition options to determine the optimal data quality and data replacement cycle relative to cost to meet the identified requirements of the user community. The evaluation demonstrated that lidar acquisition at quality level 2 for the conterminous United States and quality level 5 ifsar data for Alaska with a 6- to 10-year acquisition cycle provided the highest benefit/cost ratios. The new 3D Elevation Program (3DEP) initiative selected an 8-year acquisition cycle for the respective quality levels. 3DEP, managed by the U.S. Geological Survey (USGS), the Office of Management and Budget Circular A-16 lead agency for terrestrial elevation data, responds to the growing need for high-quality topographic data and a wide range of other 3D representations of the Nation’s natural and constructed features.

Alabama↗

USGS2020

Themes of contemporary inland fisheries goals

Goals are important for the effective execution of public trust responsibilities by state inland fisheries bureaus, but formulating meaningful goals is not simple. Often bureaus look to their past and to their sister bureaus in neighboring states when crafting goals for their own freshwater resources. Herein, we review the goal themes of fisheries bureaus using publicly available documents and guided by previous literature. We test whether goals exhibit geographic patterns presuming that differences and similarities in climate, natural resources, and people determine, to various degrees, the goal themes across the U.S. We identified nine distinct goal themes but found that they do not form clear geographic patterns, which contrasts with a similar analysis conducted in the 1970s. Since the 1970s, fisheries bureau goals have expanded and regionalism in goals has vanished. We suggest that changes in perspectives and communication technology, as well as provisions within nationwide funding mechanisms have led to goals becoming more homogenous across the U.S. and more diverse within each bureau.

Fisheries Magazine↗

USGS2004

Contribution of natural history collection data to biodiversity assessment in national parks

There has been mounting interest in the use of museum and herbaria collections to assess biodiversity; information is often difficult to locate and access, however, and few recommendations are available for effectively using natural history collections. As part of an effort to inventory vertebrates and vascular plants in U.S. national parks, we searched manually and by computer for specimens originating within or adjacent to 14 parks throughout the northeastern United States. We compared the number of specimens located to collection size to determine whether there was any effect on detection rate of specimens. We evaluated the importance of park characteristics (e.g., age since establishment, size, theme [natural vs. cultural]) for influencing the number of specimens found in a collection. We located >31,000 specimens and compiled associated records (hereafter referred to as specimens) from 78 collections; >9000 specimens were park-significant, originating either within park boundaries or in the local township where the park was located. We found >2000 specimens by means of manual searches, which cost $0.001–0.15 per specimen searched and $0.81–151.95 per specimen found. Collection effort appeared relatively uniform between 1890 and 1980, with low periods corresponding to significant sociopolitical events. Detection rates for specimens were inversely related to collection size. Although specimens were most often located in collections within the region of interest, specimens can be found anywhere, particularly in large collections international in scope, suggesting that global searches will be necessary to evaluate historical biodiversity. Park characteristics indicated that more collecting effort occurred within or adjacent to larger parks established for natural resources than in smaller historical sites. Because many institutions have not yet established electronic databases for collections, manual searches can be useful for retrieving specimens. Our results show that thorough, systematic searching of natural history collections for park-significant specimens can provide a historical perspective on biodiversity for park managers.

Conservation Biology↗

USGS2004

Fort Collins Science Center: Species and Habitats of Federal Interest

Ecosystem changes directly affect a wide variety of plant and animal species, floral and faunal communities, and groups of species such as amphibians and grassland birds. Appropriate management of public lands plays a crucial role in the conservation and recovery of endangered species and can be a key element in preventing a species from being listed under the Endangered Species Act. The Species and Habitats of Federal Interest Branch of the Fort Collins Science Center (FORT) conducts research on the ecology, habitat requirements, distribution and abundance, population dynamics, and genetics and systematics of many species facing threatened or endangered status or of special concern to resource management agencies. FORT scientists develop reintroduction and restoration techniques, technologies for monitoring populations, and novel methods to analyze data on population trends and habitat requirements. FORT expertise encompasses both traditional and specialized natural resource disciplines within wildlife biology, including population dynamics, animal behavior, plant and community ecology, inventory and monitoring, statistics and computer applications, conservation genetics, stable isotope analysis, and curatorial expertise.

Fact Sheet↗

USGS1993

U.S. Geological Survey; North Carolina's water resources; a partnership with State, Federal and local agencies

For more than 80 years, the Federal-State Cooperative Program in North Carolina has been an effective partnership that provides timely water information for all levels of government. The cooperative program has raised awareness of State and local water problems and issues and has enhanced transfer and exchange of scientific information. The U.S. Geological Survey (USGS) conducts statewide water-resources investigations in North Carolina that include hydrologic data collection, applied research studies, and other interpretive studies. These programs are funded through cooperative agreements with the North Carolina Departments of Environment, Health, and Natural Resources; Human Resources; and Transportation, as well as more than a dozen city and county governmental agencies. The USGS also conducts special studies and data-collection programs for Federal agencies, including the Department of Defense, the U.S. Soil Conservation Service, the Tennessee Valley Authority, and the U.S. Environmental Protection Agency that contribute to North Carolina's water information data base. Highlights of selected programs are presented to show the scope of USGS activities in North Carolina and their usefulness in addressing water-resource problems. The reviewed programs include the statewide data-collection program, estuarine studies, the National Water-Quality Assessment program, military installation restoration program, and groundwater flow model-development program in the Coastal Plain and Piedmont provinces.

North Carolina↗

USGS1977

Coal: special report number 2

The Fish and Wildlife Service has extensive biological expertise within the Department of Interior and exerts national leadership in the management and protection of the nation's fish and wildlife resources, their habitat, and environment. Specifically, the Office of Biological Services obtains and assimilates biological and environmental data and identifies additional informational needs and means to provide environmental and biological input into major natural resource decisions. Coal Coordinators assist in carrying out Fish and Wildlife Service involvement in the Interior Department Coal Leasing Program through a multi-stage process designed to assemble existing fish and wildlife inventory data and to prioritize fish and wildlife values in areas subject to coal leasing and associated development. This report is designed to identify possible areas of concern for wildlife and its habitat in Wyoming in the development of coal and the associate implication of land use changes. This report summarizes past and present development of the coal resource in Wyoming in anticipation of future identification of data needs for making sound resource decisions in the development of coal.

FWS/OBS↗

USGS1997

The Areal Extent of Continuous Type Gas Accumulations in Lower Silurian Clinton Sands and Medina Group Sandstones of the Appalachian Basin and the Environments Affected by Their Development

In order to best preserve and manage our energy and natural resources we must understand the relationships between these resources and the impacts of their development. To further this understanding the U.S. Geological Survey is studying unconventional continuous-type and, to a lesser extent, conventional oil and gas accumulations and the environmental impacts associated with their development. Continuous-type gas accumulations are generally characterized by low matrix permeabilities, large areal extents, and no distinct water contacts. This basin scale map shows the overall extent of these accumulations and the general land use types that may be impacted by their development. The Appalachian Basin has the longest history of oil and gas exploration and production in the United States. Since Drake's Titusville discovery well was drilled in 1859, oil and gas has been continuously produced in the basin. While there is still a great deal of oil and gas production, new field discoveries are rare and relatively small. For most of the second half of the 20th century the Appalachian basin has been considered a mature petroleum province because most of the large plays have already been discovered and developed. One exception to this trend is the Lower Silurian Clinton Sands and Medina Group Gas play which is being developed in New York, Pennsylvania, and Ohio. This continuous-type gas play has been expanding since the early 1970's (see inset maps). In the 1980's economic incentives such as large increases in wellhead prices further stimulated continuous-type gas resource development. Continuous-type gas plays can be large in areal extent and in thickness. 'Sweetspots' (areas of greater prodcution) are hard to predict and generally associated with better than average permeabilities, and enhanced by natural fracture systems. With an overall success rate often approaching 90%, drilling most of the play with closely spaced wells is often the best way to maximize gas recovery. Some positive economic characteristics associated with the development of these continuous-type accumulations are high success rates, low drilling and development costs, and low water production, which results in low water disposal costs. Large areas within the Appalachian basin with good potential for this type of gas accumulation remain to be tested. Positive environmental characteristics include, a clean energy source, low water production, and relatively low surface impact. Some negative characteristics associated with these continuous -type accumulations are low individual well production rates and small well drainage area. Negative environmental characteristics are primarily related to the dense well spacing used to develop the resource to its full potential. Often negative environmental impacts such as surface disturbance can be greatly reduced. The number of well sites can be decreased by using a single centrally located surface location and associated facilities for several directionally or horizonatally drilled wells. This also minimizes the transportation infrastructure (access roads and pipelines) required to maintain the wells and deliver the gas. Visual impacts can be reduced by selecting well locations visible only over short distances. While the prospective area is large, potential decreases basin- ward and toward the northeast and southwest. These areas are represented by the lower potential plays 6727, 6730, and 6731. The U.S. Geological Survey landuse and landcover data was derived from USGS 1:250,000 and 1:100,000 scale maps. This information was collected between the mid 1970s to mid 1980s. The land use and land cover data was mapped and coded using the Anderson classification system (Anderson, 1975) which is a hierarchical system of general (level 1) to more specific (level 2) characterization. Level 1 characterization was used for this map; the land use and land cover designations are displayed below in the Explanation. T

Open-File Report↗

USGS2016

Migratory bird habitat in relation to tile drainage and poorly drained hydrologic soil groups

The Prairie Pothole Region (PPR) is home to more than 50% of the migratory waterfowl in North America. Although the PPR provides an abundance of temporary and permanent wetlands for nesting and feeding, increases in commodity prices and agricultural drainage practices have led to a trend of wetland drainage. The Northern Shoveler is a migratory dabbling duck species that uses wetland habitats and cultivated croplands in the PPR. Richland County in North Dakota and Roberts County in South Dakota have an abundance of wetlands and croplands and were chosen as the study areas for this research to assess the wetland size and cultivated cropland in relation to hydrologic soil groups for the Northern Shoveler habitat. This study used geographic information system data to analyze Northern Shoveler habitats in association with Natural Resource Conservation Service soil data. Habitats, which are spatially associated with certain hydrologic soil groups, may be at risk of artificial drainage installations because of their proximity to cultivated croplands and soil lacking in natural drainage that may become wet or inundated. Findings indicate that most wetlands that are part of Northern Shoveler habitats were within or adjacent to cultivated croplands. The results also revealed soil hydrologic groups with high runoff potential and low water transmission rates account for most of the soil within the Northern Shoveler‘s wetland and cropland habitats. Habitats near agriculture with high runoff potential are likely to be drained and this has the potential of reducing Northern Shoveler habitat.

Conference Paper↗

USGS1981

The EROS Data Center

The Earth Resources Observation Systems (EROS) Program of the U.S. Department of the Interior, administered by the Geological Survey, was established in 1966 to apply remote-sensing techniques to the inventory, monitoring, and management of natural resources. To meet its primary objective, the EROS Program includes research and training in the interpretation and application of remotely sensed data and provides remotely sensed data at nominal cost to scientists, resource planners, managers, and the public.

South Dakota↗

USGS1977

The EROS Data Center

South Dakota↗

USGS2011

Fort Collins Science Center fiscal year 2010 science accomplishments

The scientists and technical professionals at the U.S. Geological Survey (USGS), Fort Collins Science Center (FORT), apply their diverse ecological, socioeconomic, and technological expertise to investigate complicated ecological problems confronting managers of the Nation's biological resources. FORT works closely with U.S. Department of the Interior (DOI) agency scientists, the academic community, other USGS science centers, and many other partners to provide critical information needed to help answer complex natural-resource management questions. In Fiscal Year 2010 (FY10), FORT's scientific and technical professionals conducted ongoing, expanded, and new research vital to the science needs and management goals of DOI, other Federal and State agencies, and nongovernmental organizations in the areas of aquatic systems and fisheries, climate change, data and information integration and management, invasive species, science support, security and technology, status and trends of biological resources (including the socioeconomic aspects), terrestrial and freshwater ecosystems, and wildlife resources, including threatened and endangered species. This report presents selected FORT science accomplishments for FY10 by the specific USGS mission area or science program with which each task is most closely associated, though there is considerable overlap. The report also includes all FORT publications and other products published in FY10, as well as staff accomplishments, appointments, committee assignments, and invited presentations.

Open-File Report↗

USGS2010

Groundwater-flow model and effects of projected groundwater use in the Ozark Plateaus Aquifer System in the vicinity of Greene County, Missouri — 1907-2030

Recent and historical periods of rapid growth have increased the stress on the groundwater resources in the Ozark aquifer in the Greene County, Missouri area. Historical pumpage from the Ozark aquifer has caused a cone of depression beneath Springfield, Missouri. In an effort to ease its dependence on groundwater for supply, the city of Springfield built a pipeline in 1996 to bring water from Stockton Lake to the city. Rapid population growth in the area coupled with the expanding cone of depression raised concern about the sustainability of groundwater as a resource for future use. A groundwater-flow model was developed by the U.S. Geological Survey in cooperation with Greene County, Missouri, the U. S. Army Corps of Engineers, and the Missouri Department of Natural Resources to assess the effect that increased groundwater demand is having on the long-term availability of groundwater in and around Greene County, Missouri. Three hydrogeologic units were represented in the groundwater-flow model: the Springfield Plateau aquifer, the Ozark confining unit, and the Ozark aquifer. The Springfield Plateau aquifer is less than 350 feet thick in the model area and generally is a low yield aquifer suitable only for domestic use. The Ozark aquifer is composed of a more than 900-foot thick sequence of dolomite and sandstone in the model area and is the primary aquifer throughout most of southern Missouri. Wells open to the entire thickness of the Ozark aquifer typically yield 1,000 gallons per minute or more. Between the two aquifers is the Ozark confining unit composed of as much as 98 feet of shale and limestone. Karst features such as sinkholes, springs, caves, and losing streams are present in both aquifers, but the majority of these features occur in the Springfield Plateau aquifer. The solution-enlarged fracture and bedding plane conduits in the karst system, particularly in the Springfield Plateau aquifer, are capable of moving large quantities of groundwater through the aquifer in relatively short periods of time. Pumpage rates in the model area increased from 1,093,268 cubic feet per day in 1962 to 2,693,423 cubic feet per day in 1987 to 4,330,177 cubic feet per day in 2006. Annual precipitation ranged from 25.21 inches in 1953 to 62.45 inches in 1927 from 1915 to 2006 in the model area. Recharge to the model was calculated as 2.53 percent of the annual precipitation and was varied annually. Recharge was distributed over the model area based on land slope and was adjusted in the city limits of Springfield to account for the impervious surface. A groundwater model with annual stress periods from 1907 to 2030 was developed using a transient calibration period from 1987 to 2006 and a prediction period from 2007 to 2030 to simulate flow in the Springfield Plateau aquifer and the Ozark aquifer. For the model area of approximately 2,870 square miles, the model hydrogeologic units and hydraulic properties were discretized into 253 rows, 316 columns, and 3 layers with the layer boundaries crossing hydrogeologic unit boundaries in some areas. The horizontal cell spacing was 1,000 feet by 1,000 feet. The model was calibrated by minimizing the difference between simulated head and observed water levels and simulated and observed flows in rivers and springs. Population and the associated groundwater use were estimated for 12 communities and the unincorporated area of Greene County based on past growth. Each was analyzed individually, and a low and high annual rate of growth relative to the 2006 population was computed for each community or group. Low growth rates ranged from 0.215 percent per year in Springfield to 6.997 percent per year in Rogersville. Total growth from 2006 to 2030 at the low growth rate ranged from 5.2 percent in Springfield to 167.9 percent in Rogersville. High growth rates ranged from 0.236 percent per year in Springfield to 7.345 percent per year in Rogersville. Total growth from 2006 to 2030 at the high growth rate ranged from 5.7 percent in Springfield to 176.3 percent in Rogersville. Response of the flow system to selected hypothetical pumping stresses and recharge conditions was simulated using the calibrated model. Seven hypothetical scenarios were simulated from 2007 to 2030 to test the effects of various stresses on the head in the Ozark aquifer. Hypothetical scenario 1 continued the 2006 pumping rates without change to the end of 2030. Scenario 2 assumed a low population growth rate with a 4-year drought at the beginning of the prediction period. Scenario 3 assumed a low population growth rate with a 4-year drought at the end of the prediction period. Scenario 4 assumed a high population growth rate with a 4-year drought at the beginning of the prediction period. Scenario 5 assumed a high population growth rate with a 4-year drought at the end of the prediction period. Scenario 6 and 7 had one new industrial well installed within the city limits of Springfield and one new industrial well installed about 3.5 miles east of Rogersville. Scenario 6 assumed a low population growth rate and scenario 7 assumed a high population growth rate. Results were compared by examining differences in head at the end of the simulation period. All scenarios examined resulted in potentiometric-surface declines from 2006 levels. Results from scenario 1 indicated that even with no increase in pumping, the potentiometric surface in the Springfield area continued to decline. The maximum decline of approximately 62 feet from the 2006 potentiometric surface occurred in Springfield. The maximum decline from the 2006 potentiometric surface in scenarios 2 and 3 was approximately 203 feet and in scenarios 4 and 5 was approximately 207 feet. The drought occurring at the end of the simulation period tended to broaden the drawdown area relative to the drought at the beginning. Drought timing did not substantially affect the potentiometric surface in the Ozark aquifer except for where the Ozark aquifer was exposed. Although not a substantial difference, the high population growth rate scenarios tended to have larger declines than the low population growth rate scenarios. As in the previous scenarios, little difference was noted between the low and high growth rate in scenario 6 and 7. Scenarios 6 and 7 showed declines of more than 640 feet from the 2006 potentiometric surface at the new well located in Springfield. The drawdown at the new wells decreased relatively quickly with increased distance from the well. Simulated head in the nearby cities of Nixa, Ozark, and Republic was nearly the same for scenarios 2 through 7 and was lower than the head predicted for scenario 1. Results from scenarios 2 through 7 indicate that the potentiometric surface in 2030 near these cities could decline 100 feet or more from the 2006 levels. Because model layers 2 and 3, representing the Ozark confining unit and most of the thickness of the Ozark aquifer, were simulated as confined, drawdown in the wells in the area of the Ozark aquifer that is unconfined or becomes unconfined during the simulation period will likely be under predicted.

Missouri↗

USGS1995

Genetic contribution of hatchery fish to walleye stocks in Saginaw Bay, Michigan

Stocks of walleye ( Stizostedion vitreum ) were severely depressed in Saginaw Bay in the 1970s. In 1979, the Michigan Department of Natural Resources began intensive stocking of walleye fingerlings to bolster fish populations. Subsequent to stocking, the walleye fishery has recovered. The study objective was to determine if recovery was due to the stocking program or natural reproduction. Inherent genetic differences between hatchery fish and endemic walleyes were used to determine the effect and contribution of hatchery fish to Saginaw Bay.

Michigan↗

USGS2024

Methodology for inclusion of produced and stored carbon dioxide in the U.S. Geological Survey Federal lands greenhouse gas inventory

The U.S. Geological Survey (USGS) has developed two new carbon dioxide (CO2) emissions and sequestration accounting methods for use in future reports. The first method is a Federal lease-produced CO2 emissions calculation for an update of the report, “Federal Lands Greenhouse Gas Emissions and Sequestration in the United States.” The methodology to incorporate Federal lease CO2 production emissions into the updated report relies on CO2 sales royalty data from the Office of Natural Resources Revenue (ONRR). The end usage points for the gas include enhanced oil recovery with CO2 (CO2-EOR), food and beverage, and chemical production. CO2-EOR is the main end point for natural CO2 production in the United States; it accounted for 94% of usage in 2022 [1]. Federal lands emissions from this sector are estimated at 460 metric tons of CO2 in 2022, a very small amount relative to most other Federal lands emissions sector estimates. The second new method, planned for a separate report, is a calculation of the geologic storage of CO2 on Federal lands. The second method estimates the CO2 stored under Federal surface lands and documents Federal climate change mitigation efforts. Currently, there is no storage of CO2 at an industrial level on Federal lands, however multiple proposals and projects are planned. This method was developed on non-Federal lands datasets in an effort to prepare for when these activities on Federal lands will require accounting. National estimates for CO2 geologic storage using this method, but without a Federal lands filtering step, totaled 8.0 million metric tons (Mt) in 2022. The two methods described here are new benchmark methods in a collection of accounting procedures to document the current state of greenhouse gas emissions and their storage on Federal lands. These benchmarks can then be used to measure any subsequent changes in emissions from or carbon storage beneath Federal lands. While the magnitude of the values is currently non-existent to small, emissions mitigation goals established by decision makers indicate that these values will grow, and their documentation will take on greater value and use.

continental United States↗

USGS2008

Central Colorado Assessment Project - Application of integrated geologic, geochemical, biologic, and mineral resource studies

Central Colorado is one of the fastest-growing regions in the Western United States. Population along the Front Range increased more than 30 percent between 1990 and 2000 (http://www.demographia.com/db-metro3newworld.htm) with some counties within the study area, such as Park County, experiencing greater than 100-percent growth (http://www.censusscope.org/us/s8/rank_popl_growth.html). This growth has caused tremendous demand for natural resources and has created challenging land-management issues related to the interface between wilderness and urban expansion. Management of this wilderness/urban interface will benefit from current digital geoscience information collected by the U.S. Geological Survey (USGS) Central Colorado Assessment Project that began in 2003. Approximately 20,800 square miles (53,800 km2) of land divided almost equally between the public and private sectors were part of the assessment. The study area includes much of the Colorado Mineral Belt, a northeast-trending zone that contains 30 economically significant metal deposits. Historically, the area provided much of Colorado's metal production. The only active gold and molybdenum mines in Colorado lie within the study area. Recently, metal and uranium exploration activity has increased sharply in response to record prices for metals and uranium. This further underscores the need for up-to-date geoscience information presented in compatible GIS databases to facilitate rapid land-management decisions. Cooperative studies by USDA Forest Service, National Park Service supported by the USGS Mineral Resources Program (MRP), and National Cooperative Geologic Mapping Programs (NCGMP) contributed to the mineral-resource assessment and included regional geologic mapping at the scale 1:100,000, collection and geochemical studies of stream sediments, surface water, and bedrock samples, macroinvertebrate and biofilm studies in the riparian environment, remote-sensing studies, and geochronology. Geoscience information available as GIS layers has improved understanding of the distribution of metallic, industrial, and aggregate resources, location of areas that have potential for their discovery or development, helped to understand the relation of tectonics, magmatism, and paleohydrology to the genesis of the metal deposits in the region, and provided insight on the geochemical and environmental effects that historical mining and natural, mineralized rock exposures have on surface water, ground water, and aquatic life.

Fact Sheet↗

USGS1984

Bedrock aquifers in the Denver basin, Colorado; a quantitative water-resources appraisal

The Denver metropolitan area is experiencing a rapid population growth that is requiring increasing supplies of potable water to be pumped from bedrock aquifers in order to meet demand. In an effort to determine the ability of the aquifers to continue to meet this demand, the Colorado Department of Natural Resources, the Denver Board of Water Commissioners, and Adams, Arapahoe, Douglas, Elbert and El Paso Counties joined with the U.S. Geological Survey in undertaking a hydrologic evaluation of the ground-water resources of the basin. This involved mapping of aquifer extent, thickness, structure, hydraulic characteristics, and water-level and water-quality conditions. This enabled ground-water modeling techniques to be used to simulate aquifer response to various pumpage estimates and ground-water development plans. The Laramie-Fox Hills aquifer (the deepest aquifer) underlies the 6,700-square-mile study area and is overlain by the more permeable Arapahoe aquifer, the Denver aquifer, and the Dawson aquifer, which crops out in the southern part of the study area. It is estimated that 260x10 6 acre-feet of recoverable ground water are in storage in these four bedrock aquifers. However, less than 0.1 percent of this volume of water is stored under confined conditions. The larger volume of water stored under unconfined conditions will be available for use only when the water levels in the confined aquifers decline below the top of the individual aquifer, allowing water-table conditions to develop. Annual precipitation on the Denver basin supplies an average of 6,900 cubic feet per second of water to the area; about 55 cubic feet per second of this recharges the bedrock aquifers, principally through the Dawson Arkose. The direction of ground-water movement is generally from ground-water divides in the southern part of the area northward toward the margins of the aquifers. Pumpage has ranged from about 5 cubic feet per second in 1884 to about 41 cubic feet per second in 1978. Pumpage exceeds recharge in the metropolitan area and has caused water-level declines (1958-78) to exceed 200 feet in a 135-square-mile area of the Arapahoe aquifer southeast of Denver. A quasi-three-dimensional finite-difference model of the aquifer system was constructed and calibrated under steady-state and transient-state conditions. Steady-state calibration indicated that lateral hydraulic conductivity within the aquifers is about 100,000 times larger than the vertical hydraulic conductivity between the aquifers. Transient-state calibration indicated that between 1958 and 1978, 374,000 acre-feet of water was pumped from the aquifers, producing a 90,000-acre-foot net decrease in the volume of water in storage in the aquifers. During this time, pumpage also changed the rates of interaquifer flow, induced additional recharge, and caused capture of natural discharge. Three 1979-2050 pumpage estimates were made for use in simulating the effects of various ground-water development plans. Simulations using each of these pumpage estimates indicate that by the year 2050 large water-level declines could occur, particularly in the deeper aquifers. Maximum water-level declines of 410, 1,700, and 1,830 feet were produced using the small, medium, and large pumping rates. Four plans for supplementing the Denver water supply include pumping a satellite well field, pumping a municipal well field, pumping to irrigate parks, and injecting water during periods of low demand for later use during periods of peak demand. Model simulation of these plans indicates that the satellite well field will yield twice as much water as the municipal well field, but will produce larger and more widespread water-level declines in the four aquifers. The municipal well field would not significantly affect water levels in the Dawson aquifer. Pumping the Arapahoe aquifer to supply irrigation water to selected parks was shown to produce only small water-level declines in the aquifer. Results of simulating injection-pumpage well fields at two locations indicate that simulated injection rates could range from 1.7 to 10 cubic feet per second, depending on the choice of site. The volume of water that could be stored in the bedrock aquifer is, thus, sensitive to the hydrologic characteristics of the chosen site. More study is needed to evaluate water-chemistry compatibility of native and injected water.

Colorado↗