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At least 217 records · Page 12Linked to original sources

USGS2009

Summary of surface-water quality data from the Illinois River Basin in Northeast Oklahoma, 1970-2007

The quality of streams in the Illinois River Basin of northeastern Oklahoma is potentially threatened by increased quantities of wastes discharged from increasing human populations, grazing of about 160,000 cattle, and confined animal feeding operations raising about 20 million chickens. Increasing numbers of humans and livestock in the basin contribute nutrients and bacteria to surface water and groundwater, causing greater than the typical concentrations of those constituents for this region. Consequences of increasing contributions of these substances can include increased algal growth (eutrophication) in streams and lakes; impairment of habitat for native aquatic animals, including desirable game fish species; impairment of drinking-water quality by sediments, turbidity, taste-and-odor causing chemicals, toxic algal compounds, and bacteria; and reduction in the aesthetic quality of the streams. The U.S. Geological Survey, in cooperation with the Oklahoma Scenic Rivers Commission, prepared this report to summarize the surface-water-quality data collected by the U.S. Geological Survey at five long-term surface-water-quality monitoring sites. The data summarized include major ions, nutrients, sediment, and fecal-indicator bacteria from the Illinois River Basin in Oklahoma for 1970 through 2007. General water chemistry, concentrations of nitrogen and phosphorus compounds, chlorophyll-a (an indicator of algal biomass), fecal-indicator bacteria counts, and sediment concentrations were similar among the five long-term monitoring sites in the Illinois River Basin in northeast Oklahoma. Most water samples were phosphorus-limited, meaning that they contained a smaller proportion of phosphorus, relative to nitrogen, than typically occurs in algal tissues. Greater degrees of nitrogen limitation occurred at three of the five sites which were sampled back to the 1970s, probably due to use of detergents containing greater concentrations of phosphorus than in subsequent periods. Concentrations of nitrogen, phosphorus, and sediment, and counts of bacteria generally increased with streamflow at the five sites, probably due to runoff from the land surface and re-suspension of streambed sediments. Phosphorus concentrations typically exceeded the Oklahoma standard of 0.037 milligrams per liter for Scenic Rivers. Concentrations of chlorophyll-a in phytoplankton in water samples collected at the five sites were not well correlated with streamflow, nor to concentrations of the nutrients nitrogen and phosphorus, probably because much of the algae growing in these streams are periphyton attached to streambed cobbles and other debris, rather than phytoplankton in the water column. Sediment concentrations correlated with phosphorus concentrations in water samples collected at the sites, probably due to sorption of phosphorus to soil particles and streambed sediments and runoff of soils and animal wastes at the land surface and resuspension of streambed sediments and phosphorus during wet, high-flow periods. Fecal coliform bacteria counts at the five sites sometimes exceeded the Oklahoma Primary Body Contact Standard of 400 colonies per 100 milliliters when streamflows were greater than 1000 cubic feet per second. Ultimately, Lake Tenkiller, an important ecological and economic resource for the region, receives the compounds that runoff the land surface or seep to local streams from groundwater in the basin. Because of eutrophication from increased nutrient loading, Lake Tenkiller is listed for impairment by diminished dissolved oxygen concentrations, phosphorus, and chlorophyll-a by the State of Oklahoma in evaluation of surface-water quality required by section 303d of the Clean Water Act. Stored phosphorus in soils and streambed and lakebed sediments may continue to provide phosphorus to local streams and lakes for decades to come. Steps are being made to reduce local sources of phosphorus, including upgrades in capacity and effective

Arkansas, Oklahoma↗

USGS2004

Fort Collins Science Center: Policy Analysis and Science Assistance

Most resource management decisions involve the integrated use of biological, sociological, and economic information. Combining this information provides a more comprehensive basis for making effective land management and conservation decisions. Toward this end, scientists in the Policy Analysis and Science Assistance Branch (PASA) of the Fort Collins Science Center (FORT) contribute expert knowledge for natural resources management by conducting biological, social, economic, and institutional analyses of conservation policies and management practices. PASA's mission is to integrate biological, social, and economic research so that resource managers can use the resulting information to make informed decisions and resolve resource management conflicts. PASA scientists pursue and conduct scientific analyses that help agencies and Native American tribes to (1) identify impending policy controversies and areas where social and natural science research is needed to address future policy questions; (2) develop methods and approaches to assist researchers in preparing scientific evidence; (3) assess habitat alteration in a manner consistent with policy needs; and (4) evaluate policy options. Branch scientists also evaluate policy options (e.g., effects of different land treatments, fish and wildlife management practices, or visitor/recreation management practices) in response to specific questions faced by policymakers and managers.

Fact Sheet↗

USGS2009

Assessing the landscape context and conversion risk of protected areas using satellite data products

Since the establishment of the first national park (Yellowstone National Park in 1872) and the first wildlife refuge (Pelican Island in 1903), dramatic changes have occurred in both ecological and cultural landscapes across the U.S. The ability of these protected areas to maintain current levels of biodiversity depend, at least in part, on the integrity of the surrounding landscape. Our objective was to quantify and compare the extent and pattern of natural land cover, risk of conversion, and relationships with demographic and economic variables in counties near National Park Service units and U.S. Fish and Wildlife Service refuges with those counties distant from either type of protected area in the coterminous United States. Our results indicate that landscapes in counties within 10 km of both parks and refuges and those within 10 km of just parks were more natural, more intact, and more protected than those in counties within 10 km of just refuges and counties greater than 10 km from either protected area system. However, they also had greater human population density and change in population, indicating potential conversion risk since the percent of landscape protected averaged < 5% in both groups and human population dynamics are primary drivers of change in many landscapes. Conversion outweighed protection by at least two times (Conservation Risk Index > 2) in 76% of counties near both parks and refuges, 81% of counties near just parks, 91% of counties near just refuges, and 93% of distant counties. Thirteen percent of counties in the coterminous U.S. had moderate to high amounts of natural land cover (> 60%), low protection (< 20%), and the greatest change in population (> 20%). Although these areas are not the most critically endangered, they represent the greatest conservation opportunity, need, and urgency. Our approach is based on national level metrics that are simple, general, informative, and can be understood by broad audiences and by policy makers and managers to assess the health of lands surrounding parks and refuges. Regular monitoring of these metrics with satellite data products in counties surrounding protected areas provides a consistent, national level assessment of management opportunities and potentially adverse changes on adjacent lands.

Remote Sensing of Environment↗

USGS2002

Application of landscape models to alternative futures analyses

Scientists and environmental managers alike are concerned about broadscale changes in land use and landscape pattern and their cumulative impact on environmental and economic end points, such as water quality and quantity, species habitat, productivity, erosion potential, recreational value, and overall ecological health (Rapport et al., 1998). They also are interested in predicting short-and long-term future impacts on ecological goods and services based on current land management policies and decisions (Steinitz, 1996). Because we have the means to adjust land management policies, it is worthwhile to develop approaches that can predict the consequences (alternative futures) of different land management policies for different environmental end points. This type of analysis can, for example, allow decision makers in resource conservation and restoration programs to estimate how they can get the most ecological benefit for the least cost

Delaware, Maryland, New York, Pennsylvania, Virgin↗

USGS1997

Estimating the social value of geologic map information: A regulatory application

People frequently regard the landscape as part of a static system. The mountains and rivers that cross the landscape, and the bedrock that supports the surface, change little during the course of a lifetime. Society can alter the geologic history of an area and, in so doing, affect the occurrence and impact of environmental hazards. For example, changes in land use can induce changes in erosion, sedimentation, and ground-water supply. As the environmental system is changed by both natural processes and human activities, the system's capacity to respond to additional stresses also changes. Information such as geologic maps describes the physical world and is critical for identifying solutions to land use and environmental issues. In this paper, a method is developed for estimating the economic value of applying geologic map information to siting a waste disposal facility. An improvement in geologic map information is shown to have a net positive value to society. Such maps enable planners to make superior land management decisions.

Journal of Environmental Economics and Management↗

USGS2026

Sustainability trade-offs at the nexus of solar energy, agriculture, and biodiversity

A rapid transition to renewable energy is necessary for achieving global decarbonization targets, but siting conflicts, particularly beyond the built environment, remain a key barrier to sustainable development. At the same time, climate-induced pressures on biodiversity intensify the socio-ecological trade-offs within the energy-agriculture-biodiversity nexus. Using New York State as a case study, we assess the geographic implications of utility-scale solar energy development under competing land-use priorities. We apply a mixed-integer linear programming (MILP) optimization model to evaluate solar buildout across three distinct scenarios: minimizing cost, prioritizing agricultural preservation, and conserving biodiversity, employing a lexicographic hierarchy to enforce a strict ordering of stakeholder priorities. Results indicate that New York can meet its mid-century decarbonization goals by deploying 46,216 MW dc of solar energy, however, achieving this goal involves considerable land-use trade-offs. A cost-minimizing scenario disproportionately targets pasture and hay lands (>40,000 ha), nearly half of which overlap with grassland bird habitat and broader biodiversity areas. Prioritizing agriculture spares ∼80 % of farmland but creates potential for deforestation of over 41,000 ha. Biodiversity-conscious siting avoids ecologically sensitive areas and increases the annualized total costs by 0.17 %, indicating economic feasibility. Our findings highlight the need for spatially informed, integrative land-use strategies that reconcile climate goals with ecological and agricultural values. By linking geospatial optimization with socio-ecological criteria, this work contributes a transferable framework to inform just and ecologically responsible energy transitions in multifunctional landscapes, offering new insights into how geography can advance sustainable development.

New York↗

USGS2010

Land-Use Portfolio Modeler, Version 1.0

Natural hazards pose significant threats to the public safety and economic health of many communities throughout the world. Community leaders and decision-makers continually face the challenges of planning and allocating limited resources to invest in protecting their communities against catastrophic losses from natural-hazard events. Public efforts to assess community vulnerability and encourage loss-reduction measures through mitigation often focused on either aggregating site-specific estimates or adopting standards based upon broad assumptions about regional risks. The site-specific method usually provided the most accurate estimates, but was prohibitively expensive, whereas regional risk assessments were often too general to be of practical use. Policy makers lacked a systematic and quantitative method for conducting a regional-scale risk assessment of natural hazards. In response, Bernknopf and others developed the portfolio model, an intermediate-scale approach to assessing natural-hazard risks and mitigation policy alternatives. The basis for the portfolio-model approach was inspired by financial portfolio theory, which prescribes a method of optimizing return on investment while reducing risk by diversifying investments in different security types. In this context, a security type represents a unique combination of features and hazard-risk level, while financial return is defined as the reduction in losses resulting from an investment in mitigation of chosen securities. Features are selected for mitigation and are modeled like investment portfolios. Earth-science and economic data for the features are combined and processed in order to analyze each of the portfolios, which are then used to evaluate the benefits of mitigating the risk in selected locations. Ultimately, the decision maker seeks to choose a portfolio representing a mitigation policy that maximizes the expected return-on-investment, while minimizing the uncertainty associated with that return-on-investment. The portfolio model, now known as the Land-Use Portfolio Model (LUPM), provided the framework for the development of the Land-Use Portfolio Modeler, Version 1.0 software (LUPM v1.0). The software provides a geographic information system (GIS)-based modeling tool for evaluating alternative risk-reduction mitigation strategies for specific natural-hazard events. The modeler uses information about a specific natural-hazard event and the features exposed to that event within the targeted study region to derive a measure of a given mitigation strategy`s effectiveness. Harnessing the spatial capabilities of a GIS enables the tool to provide a rich, interactive mapping environment in which users can create, analyze, visualize, and compare different

Techniques and Methods↗

USGS1979

Minerals, lands, and geology for the common defence and general welfare, Volume 1, Before 1879 : A history of public lands, federal science and mapping policy, and development of mineral resources in the United States

This volume, the first of a four-volume study, is concerned with events in the United States before the establishment of the U.S. Geological Survey, during the years in which geology evolved as a science and began to influence economic development and national policy. Subsequent volumes continue the story but focus on the Survey and its role in the events and developments of later years. The method of analysis demonstrates that knowledge of the Earth and its history, processes, and resources has provided a basis for intelligent economic development; also that geologists very soon realized that uncontrolled development of the land and other natural resources could not continue, that some limitations must be made on man's use of the Earth. The Geological Survey was established when public awareness of the need for balance between development and conservation of our resources was becoming evident. That balance is even more necessary now and in the future for the "general welfare" and "common defence" of the Nation. We can be grateful for the wisdom of our Founding Fathers in providing for publicly supported studies in earth science and engineering by well-trained and motivated scientists and engineers. Such studies, undertaken objectively in the search for facts, can continue to be of great value in the formulation and execution of wise policies to protect our environment and to maintain that balance between development and conservation of the natural resources.

Book↗

USGS1981

Arid land monitoring using Landsat albedo difference images

The Landsat albedo, or percentage of incoming radiation reflected from the ground in the wavelength range of 0.5 [mu]m to 1.1 [mu]m, is calculated from an equation using the Landsat digital brightness values and solar irradiance values, and correcting for atmospheric scattering, multispectral scanner calibration, and sun angle. The albedo calculated for each pixel is used to create an albedo image, whose grey scale is proportional to the albedo. Differencing sequential registered images and mapping selected values of the difference is used to create quantitative maps of increased or decreased albedo values of the terrain. All maps and other output products are in black and white rather than color, thus making the method quite economical. Decreases of albedo in arid regions may indicate improvement of land quality; increases may indicate degradation. Tests of the albedo difference mapping method in the Desert Experimental Range in southwestern Utah (a cold desert with little long-term terrain change) for a four-year period show that mapped changes can be correlated with erosion from flash floods, increased or decreased soil moisture, and increases or decreases in the density of desert vegetation, both perennial shrubs and annual plants. All terrain changes identified in this test were related to variations in precipitation. Although further tests of this method in hot deserts showing severe "desertification" are needed, the method is nevertheless recommended for experimental use in monitoring terrain change in other arid and semiarid regions of the world.

Utah↗

USGS1978

Spectrographic and chemical analyses of whole-rock and insoluble-residue samples, Rolla 1 degree x 2 degrees quadrangle, Missouri: Drill hole no. 12

Geochemical studies of the Rolla, Mo., 1° x 2° quadrangle were begun in 1977 as a part of a joint multidisciplinary study of the quadrangle by the U.S. Geological Survey and the Division of Geology and Land Survey, Missouri Department of Natural Resources. The study is to access the mineral resource potential of the area by integrated geologic, geochemical, and geophysical studies. The geochemical work to date has been directed at the characterization of the sedimentary and igneous rocks in the quadrangle through spectrographic and chemical analyses of whole-rock samples and dilute-hydrochloric-acid insoluble-residue samples of whole rock from widely spaced drill holes. Sixty-two drill holes have been selected for study from the sample library of the Missouri Division of Geology and Land Survey. None of the holes are company confidential, none intersect economically significant mineralized ground, and only a few are located in known ore-bearing trends. The analytical results for drill hole No. 12, Missouri log numbers 12195 and 12339, are given in this report. The drill hole is located in sec. 18, T. 34 N., R. 5 W. in Reynolds County. Data of the whole-rock samples are listed in table 1, and data of the insoluble-residue samples are listed in table 2. Missouri log number, county, and location allow correlation with the stratigraphic logs on file at the Missouri Division of Geology and Land Survey in Rolla, Mo.

Missouri↗

USGS2017

Multi-scale 46-year remote sensing change detection of diamond mining and land cover in a conflict and post-conflict setting

The town of Tortiya was created in the rural northern region of Côte d′Ivoire in the late 1940s to house workers for a new diamond mine. Nearly three decades later, the closure of the industrial-scale diamond mine in 1975 did not diminish the importance of diamond profits to the region's economy, and resulted in the growth of artisanal and small-scale diamond mining (ASM) within the abandoned industrial-scale mining concession. In the early 2000s, the violent conflict that arose in Côte d′Ivoire highlighted the importance of ASM land use to the local economy, but also brought about international concerns that diamond profits were being used to fund the rebellion. In recent years, cashew plantations have expanded exponentially in the region, diversifying economic activity, but also creating the potential for conflict between diamond mining and agricultural land uses. As the government looks to address the future of Tortiya and this potential conflict, a detailed spatio-temporal understanding of the changes in these two land uses over time may assist in informing policymaking. Remotely sensed imagery presents an objective and detailed spatial record of land use/land cover (LULC), and change detection methods can provide quantitative insight regarding regional land cover trends. However, the vastly different scales of ASM and cashew orchards present a unique challenge to comprehensive understanding of land use change in the region. In this study, moderate-scale categories of LULC, including cashew orchards, uncultivated forest, urban space, mining/ bare, and mixed vegetation, were produced through supervised classification of Landsat multispectral imagery from 1984, 1991, 2000, 2007, and 2014. The fine-scale ASM land use was identified through manual interpretation of annually acquired high resolution satellite imagery. Corona imagery was also integrated into the study to extend the temporal duration of the remote sensing record back to the period of industrial-scale mining. These different-scale analyses were then integrated to create a record of 46 years of mining activity and land cover change in Tortiya. While similar in spatial extent, the mining/ bare class in the integrated analysis exhibits a substantially different spatial distribution than in the original classifications. This additional information regarding the locations of ASM activity in the Tortiya area is important from a policy and planning perspective. The results of this study also suggest that LULC classifications of Landsat imagery do not consistently capture areas of ASM in the Côte d′Ivoire landscape.

Remote Sensing Applications: Society and Environme↗

USGS2010

Influence of potential sea level rise on societal vulnerability to hurricane storm-surge hazards, Sarasota County, Florida

Although the potential for hurricanes under current climatic conditions continue to threaten coastal communities, there is concern that climate change, specifically potential increases in sea level, could influence the impacts of future hurricanes. To examine the potential effect of sea level rise on community vulnerability to future hurricanes, we assess variations in socioeconomic exposure in Sarasota County, FL, to contemporary hurricane storm-surge hazards and to storm-surge hazards enhanced by sea level rise scenarios. Analysis indicates that significant portions of the population, economic activity, and critical facilities are in contemporary and future hurricane storm-surge hazard zones. The addition of sea level rise to contemporary storm-surge hazard zones effectively causes population and asset (infrastructure, natural resources, etc) exposure to be equal to or greater than what is in the hazard zone of the next higher contemporary Saffir–Simpson hurricane category. There is variability among communities for this increased exposure, with greater increases in socioeconomic exposure due to the addition of sea level rise to storm-surge hazard zones as one progresses south along the shoreline. Analysis of the 2050 comprehensive land use plan suggests efforts to manage future growth in residential, economic and infrastructure development in Sarasota County may increase societal exposure to hurricane storm-surge hazards.

Florida↗

USGS2012

Adaptation to climate change: changes in farmland use and stocking rate in the U.S.

This paper examines possible adaptations to climate change in terms of pasture and crop land use and stocking rate in the United States (U.S.). Using Agricultural Census and climate data in a statistical model, we find that as temperature and precipitation increases agricultural commodity producers respond by reducing crop land and increasing pasture land. In addition, cattle stocking rate decreases as the summer Temperature-humidity Index (THI) increases and summer precipitation decreases. Using the statistical model with climate data from four General Circulation Models (GCMs), we project that land use shifts from cropping to grazing and the stocking rate declines, and these adaptations are more pronounced in the central and the southeast regions of the U.S. Controlling for other farm production variables, crop land decreases by 6 % and pasture land increases by 33 % from the baseline. Correspondingly, the associated economic impact due to adaptation is around -14 and 29 million dollars to crop producers and pasture producers by the end of this century, respectively. The national and regional results have implications for farm programs and subsidy policies.

Mitigation and Adaptation Strategies for Global Ch↗

USGS1994

Wildlife habitat management on the northern prairie landscape

The northern prairie landscape has changed dramatically within the past century as a result of settlement by Europeans. Natural ecosystems have been disrupted and wildlife populations greatly altered. Natural resource agencies control only limited areas within the landscape, which they cannot manage independently of privately owned lands. Wildlife managers need first to set quantifiable objectives, based on the survival, reproduction, and distribution of wildlife. Second, they need to build public support and partnerships for meeting those objectives. Finally, they need to evaluate progress not only with respect to attitudes of the public and partners but, more importantly, of the wildlife response. This paper describes some useful tools for managing information at all phases of this process. We follow by discussing management options at a landscape level. Examples are given that involve agency lands as well as private lands, managed for biological resources and diversity as well as economic sustainability.

Landscape and Urban Planning↗

USGS1982

Mineral resource potential map of the Rock Pile Mountain Wilderness Study area, Madison County, Missouri

Although the Rock Pile Mountain Wilderness Study Area is within the general boundary of the Southeast Missouri mining district, it has no record of mineral production and there is no mining or prospecting activity at present. Exploratory drill holes on private land along the west side of the area encountered no economic mineralization. Neither the Precambrlan volcanic rocks nor the Cambrlan sedimentary rocks contain any detectable evidence of economic mineralization. The area has no potential for coal resources, an unfavorable potential for oil and gas, and no known potential for geothermal energy. The volcanic rocks might be suitable for use as crushed stone, but similar rocks occur abundantly in more favorable locations elsewhere.

Missouri↗

USGS1966

Extent and frequency of inundation of Schuylkill River flood plain from Conshohocken to Philadelphia, Pennsylvania

Information on flood conditions plays an important part in the development and use of river valleys. This report presents maps, profiles, and flood-frequency relations developed from past flood experience on the Schuylkill River from Conshohocken to Philadelphia, Pa. The maps and profiles are used to define the areal extent and depth of flooding of the August 24, 1933, and August 19, 1955, floods. The flood of October 4, 1869, which is the greatest flood known on the lower Schuylkill River, is presented on the flood profile and on the ten cross sections. The area inundated by the 1869 flood is not defined because insufficient data are available and because hydrologic and hydraulic conditions have undoubtedly changed to such an extent that such a definition would have little present significance. The basic flood data were prepared to aid individuals, organizations, and governmental agencies in making sound decisions for the safe and economical development of the lower Schuylkill River valley. Recommendations for land use, or suggestions for limitations of land use, are not made in this report. The responsibility for planning for the optimum land use in the flood plain and the implementation of flood-plain regulations to achieve such optimum use rests with the State and local interests. The preparation of this report was undertaken after consultation with representatives of the Philadelphia City Planning Commission and the Montgomery County Planning Commission who expressed the need for flood-plain information and their willingness to consider floodplain regulations. The area covered by this report extends downstream along the Schuylkill River from Plymouth Dam in Conshohocken to the mouth of Wissahickon Creek in Philadelphia. Flooding along Wissahickon Creek is not included in the report. The reach studied extends from 13.0 miles to 21.0 miles upstream from the river mouth. All river distances used in the report are river miles upstream from the mouth of the Schuylkill River as used by the Corps of Engineer, U.S. Army and by the U.S. Geological Survey (Bogart, 1960, p. 194). For the convenience of users a tabulation of river miles of selected points upstream from the mouth of the Schuylkill River is included at the end of this report (table 1).

Pennsylvania↗

USGS2010

Global mineral resource assessment

Introduction In response to the growing demand for information on the global mineral-resource base, the U.S. Geological Survey (USGS) is conducting the Quantitative Global Mineral Resource Assessment Project (GMRAP), a cooperative international project, begun in 2002, to assess the world's undiscovered nonfuel mineral resources. Primary Objectives The USGS conducts national and global assessments of resources (mineral, energy, water, biologic) to provide science in support of decisionmaking. Mineral resource assessments provide a synthesis of available information about where mineral deposits are known and suspected in the Earth’s crust, what commodities may be present, and estimates of amounts of resources that may be present in undiscovered deposits. The Global Mineral Resource Assessment Project started in 2002 as a cooperative international effort to assess the world’s undiscovered nonfuel mineral resources. Primary objectives are to: Outline the regional locations and estimate the probable amounts of the world’s undiscovered resources of copper, platinum-group elements (PGE), and potash in selected types of mineral deposits to depths of 1 to 3 kilometers below the Earth’s surface. Provide the first globally consistent and comprehensive analysis of undiscovered nonfuel mineral resources to provide all nations with a regional and global context for evaluating their mineral resources, planning for new mineral exploration and anticipating the economic, environmental, and social impacts of mineral development, and making land use decisions. The project emphasizes the most important types of mineral deposits for world supply of copper, platinum-group elements (PGE) and nickel, and potash. Go to the Quantitative Global Mineral-Resource Assessments home page for more information.

Scientific Investigations Report↗

USGS1968

Water for the growing needs of Harrison County, Mississippi

The potential for water-supply development in Harrison County is almost unlimited. During an average year, more than 350 billion gallons of water flow into the Gulf of Mexico from the streams of the county. With storage reservoirs these streams have a potential sustained supply of hundreds of millions of. gallons per day. Recreation uses and flood-control benefits could also be considered in reservoir design. Upstream from the zones of salt-water penetration, mineral content is low and fairly constant. Water in the streams generally has high color and low pH ; treatment would be required for most municipal and industrial uses. Impoundment in reservoirs normally would have little effect on the quality of the surface water. However, impoundment would trap most of the suspended-sediment load of the streams. Flooding along the major streams of Harrison County is a minor hazard at present (1966), but with further industrial development and urbanization, flooding in these now rural areas could become serious. Intense rainfall from thunderstorms and hurricanes causes serious local flooding in the populous areas near the coast. Tidal flooding, a result of tropical storms, is an ever-present hazard in areas near the coast. The ground-water reservoir, which at present provides all fresh-water supplies, is capable of supporting many times the 25 million gallons per day withdrawal through existing wells. Fresh water occurs to depths as great as 2,500 feet in sand aquifers of Pliocene and Miocene age. Many of the aquifers have high transmissibility; most of those tested have transmissibility in the range, of 50,000-100,000 gallons per day per foot. Although few wells produce more than 1,000 gallons per minute, several of the aquifers can yield two to three times that amount to wells designed for the higher production. Artesian water levels along the coast are declining at a rate of 1 foot per year on the average; however, water levels are still above or only slightly below the land surface in most places, and considerable additional drawdown is economically available. Newly discovered deep aquifers (1,700-2,500 ft) have water levels 100 feet above the surface and probably will provide flow yields of 2,000 gallons per minute or more. The temperature of this deep water is nearly 100?F. Nearly all the ground water is of good quality and requires little or no treatment for most uses. It is soft, and total mineral content is usually less than 250 parts per million. Color is seldom a problem, although it may have to be considered in the undeveloped deep aquifers. The pH ordinarily is greater than 7.0, but it is slightly less than 7.0 in most places in the shallow aquifers.

Water Supply Paper↗