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At least 55 records · Page 3Linked to original sources
USGS1982

Deep artesian aquifers of Sanibel and Captiva Islands, Lee County, Florida

Sanibel and Captiva Islands, two of the barrier islands off the lower west coast of Florida, have a resident population of about 6,000 and an additional 6,000 visitors during the peak of the tourist season. Rapid growth and extensive development in recent years have imposed progressively greater stress on the water resources of the islands. Sanibel and Captiva Islands are underlain by a series of geologic formations containing some zones of relatively freshwater and other zones of more mineralized, or even very saline water. Two aquifers are the principal sources of water supply on the islands. The upper aquifer is in the upper part of the Hawthorn Formation. The lower aquifer is in the lower part of the Hawthorn Formation and the underlying upper part of the Tampa Limestone. Both aquifers are under sufficient artesian pressure to permit wells to flow at land surface. The potentiometric surface of the lower Hawthorn-upper Tampa aquifer has been lowered in the central part of Sanibel Island where the Island Water Association operates about 10 wells that tap the lower aquifer. In 1977, the average pumpage from these 10 wells was 1.4 million gallons per day. The water is processed through a desalination plant before distribution. In 1977, the total volume of water withdrawn from both the lower and upper aquifers for all purposes was 690 million gallons, an average of about 1.9 million gallons per day. Water from the upper Hawthorn aquifer during the period 1975-77 contained dissolved solids concentrations ranging from 721 to 2,390 milligrams per liter. Water from the lower Hawthorn-upper Tampa aquifer during the same period contained concentrations ranging from 1,700 to 4,130 milligrams per liter. Water from both aquifers is hard and contains relatively high concentrations of sodium, sulfate, and chloride.

Florida↗
USGS1985

Proposed artificial recharge studies in northern Qatar

The aquifer system in northern Qatar comprises a water-table aquifer in the Rus Formation which is separated by an aquitard from a partially confined aquifer in the top of the overlying Umm er Radhuma Formation. These two aquifers are composed of limestone and dolomite of Eocene and Paleocene age and contain a fragile lens of freshwater which is heavily exploited as a source of water for agricultural irrigation. Net withdrawals are greatly in excess of total recharge, and quality of ground water is declining. Use of desalinated seawater for artificial recharge has been proposed for the area. Artificial recharge, on a large scale, could stabilize the decline in ground-water quality while allowing increased withdrawals for irrigation. The proposal appears technically feasible. Recharge should be by injection to the Umm er Radhuma aquifer whose average transmissivity is about 2,000 meters squared per day (as compared to an average of about 200 meters squared per day for the Rus aquifer). Implementation of artificial recharge should be preceded by a hydrogeologic appraisal. These studies should include test drilling, conventional aquifer tests, and recharge-recovery tests at four sites in northern Qatar. (USGS)

Open-File Report↗
USGS1979

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

The Lower Mississippi Region comprises an area of 102,400 square miles (265,200 square kilometers). Almost all this area is in the physiographic province known as the Gulf Coastal Plain. Three small areas on the northwest boundary of the region are in the Interior Highlands. The Lower Mississippi Region has an abundance of ground water. The geologic structure in that part of the region within the Coastal Plain is an elongated trough which has been filled with permeable materials, resulting in vast subsurface reservoirs. Except in local areas where continued large withdrawals have caused significant water-level declines, these reservoirs are full. Recharge to the region's aquifers is primarily from rainfall. Annual rainfall in most of the region is well distributed throughout the year and is sufficient to satisfy evapotranspiration requirements and still provide recharge to the aquifers. An estimated 844 billion cubic feet (24 billion cubic meters) of fresh ground water is available for withdrawal annually in the region. Only about one-third of this quantity is being utilized. Therefore, on this basis alone, the region still has much potential for ground-water development. The Coastal Plain aquifers within the Lower Mississippi Region contain large reserves of saltwater in the downdip limits of the aquifers. The quantity of saltwater in the region is several times that of freshwater. As desalinization techniques are developed and as more uses are found for saltwater, this reserve could become an important source of water for the region. At present (1976), the most productive and potentially productive aquifers or aquifer systems in the region are the Mississippi River valley alluvial aquifer of Quaternary age and the Sparta Sand and the Memphis aquifer (Memphis Sand in Tennessee) of Tertiary age. The Sparta Sand and the Memphis aquifer are heavily utilized and have shown significant water-level declines. However, selected well hydrographs indicate that water levels may be stabilizing under present pumping conditions. The Mississippi River valley alluvial aquifer is the most extensive high-yielding aquifer in the region; yields of several thousand gallons per minute may be obtained at depths of less than 200 feet (61 meters). To obtain maximum benefit from the vast quantities of ground water in the region, adequate attention must be given to the effects of proposed development upon the ground-water regime. Knowledge of the geologic structure and hydraulic properties of the aquifer systems is essential to an evaluation of the effects of such development. Some studies have been made in sufficient detail to provide this knowledge, but additional studies are needed. Activities that could cause significant changes in the groundwater regime should be undertaken only after all available information has been considered. Failure to seek out and use such information may result in inefficient development of the groundwater resource and, in some instances, degradation of the quality of the resource. Some changes always result from ground-water development. The possible changes can be grouped into three categories: hydraulic, water quality, and those affecting the physical framework of the aquifers. Generally, they are small in magnitude and areal extent. Because these changes occur below the ground surface, they are unknown to the ground-water user unless they noticeably affect the quantity or quality of water produced or cause obvious physical effects, such as land subsidence. Great advances have been made in hydrologic technology in recent years. Predictive models have been developed that make it possible for the hydroiogist to simulate aquifer responses to proposed development or other stresses. These models would be invaluable tools in progressive water-resources planning and management.

Arkansas, Kentucky, Louisiana, Mississippi, Missou↗
USGS1979

Summary appraisals of the nation's ground-water resources– South Atlantic-Gulf region

Precipitation in the 270,000-square-mile South Atlantic-Gulf Region ranges from 44 to 80 inches, and the average runoff is about 15 inches. The ground-water discharge that forms the base flow of streams is conservatively estimated to be about 78,000 million gallons per day the equivalent of about 6 inches of precipitation. On this basis, the regional sustained ground-water supply is about 286,000 gallons per day per square mile. Projected water use through 2020 indicates that about 10 percent of the supply will meet the region's requirement for ground water. Enormous quantities of ground water are available in the South Atlantic-Gulf States in the extensive aquifers that underlie the Coastal Plain province. Large supplies of ground water can be developed also in places in the Cumberland Plateau and the Valley and Ridge provinces. In the Piedmont and Blue Ridge provinces ground water is available only in modest quantities. The principal Coastal Plain aquifers consist largely of deltaic sand and gravel deposits of Cretaceous to Quaternary age; however, a notable exception is the highly permeable Tertiary limestone aquifer, which underlies parts of four States. Ground water in the Blue Ridge and the Valley and Ridge provinces is available from openings along fissures and joints in consolidated rocks and from the unconsolidated sand and gravel in the residuum and alluvium that overlie the bedrock. In parts of these areas faulting and folding has created favorable conditions for the development of moderate supplies of ground water. In the Piedmont province modest quantities of water are available from joints and fractures. Solution cavities in massive limestone units in some areas underlying the Cumberland Plateau section yield very large quantities of ground water. Most of the major Coastal Plain aquifers are recharged where they are exposed and water moves downdip to the south. The general direction of ground-water movement in the Coastal Plain aquifers is seaward. There is, however, movement of water vertically and laterally that affects pressure and quality in every aquifer. Ground water of good chemical and physical quality is available generally except in a small area in western Alabama and eastern Mississippi and in some small coastal areas. Freshwater extends to depths of slightly more than 3,000 feet in some areas. In many areas, water can be produced that does not require any treatment for general use. The more common objectionable constituents or properties are excessive iron, fluoride, hardness, color, and acidity. Contamination or pollution of ground water is not a major regional problem, but it is significant in local areas. Many of these local problems of contamination were the result of earlier improper disposal of oil-field and industrial waste. Saltwater intrusion either directly from the sea or from estuaries has been reported in every State in the region, and the potential for the proliferation of this problem is very large. The relationship of ground water and surface water is significant at many places in the region where large ground-water withdrawals affect swamps, lakes, and the flow of streams and springs. There is a potential in some areas for using ground water during dry periods for low-flow augmentation of stream supplies. In other areas it is feasible to recharge ground-water reservoirs artificially by means of injection wells, pits, and water spreading. Although large water-level declines caused by withdrawals have occurred locally, water-level changes have been small or modest when considered on a regional basis owing to the abundant rainfall and favorable recharge conditions. The saline-water resources of the region are known to be extremely large. In some areas where the availability of freshwater is limited, saline ground water is available for desalinization to supplement freshwater supplies. Also, the saline aquifers are potential storage sites for injected freshwater. Ground-water problems generally are not severe. Critical situations are restricted to areas where large quantities of ground water are being withdrawn or where aquifers are contaminated by oil-field or industrial waste. Large withdrawals in coastal areas have caused some saltwater intrusion. In other localities, highly mineralized water may have migrated along fault zones to freshwater aquifers. Many of the present problems can be resolved or ameliorated by redistributing withdrawals or developing alternative water sources.

Alabama, Florida, Georgia, Mississippi, North Caro↗
USGS1980

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

The Caribbean Region consists of the Commonwealth of Puerto Rico (8,990 km 2 (square kilometers)) and the U.S. Virgin Islands (350 km 2 ). The mean annual precipitation varies locally from a high of 5,000 mm (millimeters) to a low of 730 mm. Maximum precipitation occurs within the peaks of Sierra de Luquillo, and minimum precipitation occurs along the windward parts of the smaller islands and in southwestern Puerto Rico, which lies in a rain shadow. The annual average precipitation is 1,800 mm in Puerto Rico and 1,061 mm in the U.S. Virgin Islands. Of this amount 1,130 mm in Puerto Rico and 990 mm in the U.S. Virgin Islands are lost to evapotranspiration. Aquifers constitute a valuable resource in the Caribbean Region. In Puerto Rico, ground-water withdrawals supply about 38 percent of the total water requirements, whereas in the U.S. Virgin Islands they supply 10 percent. Of the ground-water withdrawal of 350 hm 3 /yr (cubic hectometers per year) in Puerto Rico, 54 percent is used for irrigation, 29 percent is used by industry, and 17 percent is used for public water supply. Ground-water withdrawal in the U.S. Virgin Islands is about 1.9 hm 3 /yr and is almost equally distributed between public supply and privately owned wells. Based on past trends and future economic expectations in the region, estimates are that by 1985 ground-water pumpage in Puerto Rico will be about 426 hm 3 /yr with additional future development potential; U.S. Virgin Islands pumpage may amount to 4.5 hm 3 /yr, which is the estimated maximum sustained yield of all aquifers under natural recharge conditions. Most large ground-water developments in Puerto Rico have been in the North Coast and South Coast ground-water provinces. The North Coast province contains the island's most productive aquifer, which was virtually undeveloped until 1968, when an artesian system having a 150-meter head was tapped. Since then, the artesian aquifer has undergone rapid development for industrial water supply. The extent of the artesian system is unknown, but it has been tapped within the Montebello Limestone Member of the Cibao Formation and in the upper part of the Lares Limestone. The south-coast aquifer consists of deep alluvial deposits. This aquifer has been extensively developed for irrigation and industrial water supply and can sustain only minor future development under present water-management conditions. In the U.S. Virgin Islands the most extensive aquifer is fragmented igneous rock, but the most productive aquifers are the marl and alluvial deposits of central St. Croix. Although yields from wells in central St. Croix are low (less than 6.3 liters per second), the aquifer provides about 0.86 hm 3 /yr to public water-supply wells and 0.54 hm 3 /yr to private wells. Future development within this aquifer could probably produce an additional 1.0 hm 3 /yr under natural infiltration conditions. Ground-water resources will continue to be important within the region. In order to meet future needs, it is necessary that hydrologic principles be applied in managing the total water resource. Optimal use of the water resources can be accomplished through conjunctive use of surface and ground waters and through conservation practices. Optimal use may involve artificial recharge, ground-water salvage, saline-ground-water mining, use of seawater, desalination of saline ground water, waste-water reuse, and use of underground space for temporary storage of wastes, which could otherwise contaminate valuable water supplies.

Professional Paper↗
USGS2008

Potentiometric Surface of the Upper Floridan Aquifer, West-Central Florida, May 2008

The Floridan aquifer system consists of the Upper and Lower Floridan aquifers separated by the middle confining unit. The middle confining unit and the Lower Floridan aquifer in west-central Florida generally contain highly mineralized water. The water-bearing units containing fresh water are herein referred to as the Upper Floridan aquifer. The Upper Floridan aquifer is the principal source of water in the Southwest Florida Water Management District and is used for major public supply, domestic use, irrigation, and brackish water desalination in coastal communities (Southwest Florida Water Management District, 2000). This map report shows the potentiometric surface of the Upper Floridan aquifer measured in May 2008. The potentiometric surface is an imaginary surface connecting points of equal altitude to which water will rise in tightly-cased wells that tap a confined aquifer system (Lohman, 1979). This map represents water-level conditions near the end of the dry season, when ground-water levels usually are at an annual low and withdrawals for agricultural use typically are high. The cumulative average rainfall of 46.95 inches for west-central Florida (from June 2007 through May 2008) was 5.83 inches below the historical cumulative average of 52.78 inches (Southwest Florida Water Management District, 2008). Historical cumulative averages are calculated from regional rainfall summary reports (1915 to most recent complete calendar year) and are updated monthly by the Southwest Florida Water Management District. This report, prepared by the U.S. Geological Survey in cooperation with the Southwest Florida Water Management District, is part of a semi-annual series of Upper Floridan aquifer potentiometric-surface map reports for west-central Florida. Potentiometric-surface maps have been prepared for January 1964, May 1969, May 1971, May 1973, May 1974, and for each May and September since 1975. Water-level data are collected in May and September each year to show the approximate annual low and high water-level conditions, respectively. Most of the water-level data for this map were collected by the U.S. Geological Survey during the period May 19-23, 2008. Supplemental water-level data were collected by other agencies and companies. A corresponding potentiometric-surface map was prepared for areas east and north of the Southwest Florida Water Management District boundary by the U.S. Geological Survey office in Orlando, Florida (Kinnaman and Dixon, 2008). Most water-level measurements were made during a 5-day period; therefore, measurements do not represent a 'snapshot' of conditions at a specific time, nor do they necessarily coincide with the seasonal low water-level condition.

Scientific Investigations Map↗
USGS2009

Potentiometric Surface of the Upper Floridan Aquifer, West-Central Florida, September 2008

The Floridan aquifer system consists of the Upper and Lower Floridan aquifers separated by the middle confining unit. The middle confining unit and the Lower Floridan aquifer in west-central Florida generally contain highly mineralized water. The water-bearing units containing fresh water are herein referred to as the Upper Floridan aquifer. The Upper Floridan aquifer is the principal source of water in the Southwest Florida Water Management District and is used for major public supply, domestic use, irrigation, and brackish water desalination in coastal communities (Southwest Florida Water Management District, 2000). This map report shows the potentiometric surface of the Upper Floridan aquifer measured in September 2008. The potentiometric surface is an imaginary surface connecting points of equal altitude to which water will rise in tightly-cased wells that tap a confined aquifer system (Lohman, 1979). This map represents water-level conditions near the end of the wet season, when ground-water levels usually are at an annual high and withdrawals for agricultural use typically are low. The cumulative average rainfall of 50.63 inches for west-central Florida (from October 2007 through September 2008) was 2.26 inches below the historical cumulative average of 52.89 inches (Southwest Florida Water Management District, 2008). Historical cumulative averages are calculated from regional rainfall summary reports (1915 to most recent complete calendar year) and are updated monthly by the Southwest Florida Water Management District. This report, prepared by the U.S. Geological Survey in cooperation with the Southwest Florida Water Management District, is part of a semi-annual series of Upper Floridan aquifer potentiometric-surface map reports for west-central Florida. Potentiometric-surface maps have been prepared for January 1964, May 1969, May 1971, May 1973, May 1974, and for each May and September since 1975. Water-level data are collected in May and September each year to show the approximate annual low and high water-level conditions, respectively. Most of the water-level data for this map were collected by the U.S. Geological Survey during the period September 15-19, 2008. Supplemental water-level data were collected by other agencies and companies. A corresponding potentiometric-surface map was prepared for areas east and north of the Southwest Florida Water Management District boundary by the U.S. Geological Survey office in Orlando, Florida (Kinnaman and Dixon, 2009). Most water-level measurements were made during a 5-day period; therefore, measurements do not represent a 'snapshot' of conditions at a specific time, nor do they necessarily coincide with the seasonal high water-level condition.

Scientific Investigations Map↗
USGS2009

Potentiometric Surface of the Upper Floridan Aquifer, West-Central Florida, May 2009

The Floridan aquifer system consists of the Upper and Lower Floridan aquifers separated by the middle confining unit. The middle confining unit and the Lower Floridan aquifer in west-central Florida generally contain highly mineralized water. The water-bearing units containing fresh water are herein referred to as the Upper Floridan aquifer. The Upper Floridan aquifer is the principal source of water in the Southwest Florida Water Management District and is used for major public supply, domestic use, irrigation, and brackish water desalination in coastal communities (Southwest Florida Water Management District, 2000). This map report shows the potentiometric surface of the Upper Floridan aquifer measured in May 2009. The potentiometric surface is an imaginary surface connecting points of equal altitude to which water will rise in tightly-cased wells that tap a confined aquifer system (Lohman, 1979). This map represents water-level conditions near the end of the dry season, when ground-water levels usually are at an annual low and withdrawals for agricultural use typically are high. The cumulative average rainfall of 48.53 inches for west-central Florida (from June 2008 through May 2009) was 4.12 inches below the historical cumulative average of 52.65 inches (Southwest Florida Water Management District, 2009). Historical cumulative averages are calculated from regional rainfall summary reports (1915 to most recent complete calendar year) and are updated monthly by the Southwest Florida Water Management District. This report, prepared by the U.S. Geological Survey in cooperation with the Southwest Florida Water Management District, is part of a semi-annual series of Upper Floridan aquifer potentiometric-surface map reports for west-central Florida. Potentiometric-surface maps have been prepared for January 1964, May 1969, May 1971, May 1973, May 1974, and for each May and September since 1975. Water-level data are collected in May and September each year to show the approximate annual low and high water-level conditions, respectively. Most of the water-level data for this map were collected by the U.S. Geological Survey during the period May 18-22, 2009. Supplemental water-level data were collected by other agencies and companies. A corresponding potentiometric-surface map was prepared for areas east and north of the Southwest Florida Water Management District boundary by the U.S. Geological Survey office in Orlando, Florida (Kinnaman and Dixon, 2009). Most water-level measurements were made during a 5-day period; therefore, measurements do not represent a 'snapshot' of conditions at a specific time, nor do they necessarily coincide with the seasonal low water-level condition. The potentiometric contours are generalized to synoptically portray the head in a dynamic hydrologic system, taking due account of the variations in hydrogeologic conditions, such as differing depths of wells, nonsimultaneous measurements of water levels, variable effects of pumping, and changing climatic influence. The potentiometric contours may not conform exactly with the individual measurements of water levels.

Scientific Investigations Map↗
USGS2010

Potentiometric Surface of the Upper Floridan Aquifer, West-central Florida, May 2010

The Floridan aquifer system consists of the Upper and Lower Floridan aquifers separated by the middle confining unit. The middle confining unit and the Lower Floridan aquifer in west-central Florida generally contain highly mineralized water. The water-bearing units containing fresh water are herein referred to as the Upper Floridan aquifer. The Upper Floridan aquifer is the principal source of water in the Southwest Florida Water Management District and is used for major public supply, domestic use, irrigation, and brackish water desalination in coastal communities (Southwest Florida Water Management District, 2000). This map report shows the potentiometric surface of the Upper Floridan aquifer measured in May 2010. The potentiometric surface is an imaginary surface connecting points of equal altitude to which water will rise in tightly-cased wells that tap a confined aquifer system (Lohman, 1979). This map represents water-level conditions near the end of the dry season, when groundwater levels usually are at an annual low and withdrawals for agricultural use typically are high. The cumulative average rainfall of 55.21 inches for west-central Florida (from June 2009 through May 2010) was 2.55 inches above the historical cumulative average of 52.66 inches (Southwest Florida Water Management District, 2010). Historical cumulative averages are calculated from regional rainfall summary reports (1915 to most recent complete calendar year) and are updated monthly by the Southwest Florida Water Management District. This report, prepared by the U.S. Geological Survey in cooperation with the Southwest Florida Water Management District, is part of a semi-annual series of Upper Floridan aquifer potentiometric-surface map reports for west-central Florida. Potentiometric-surface maps have been prepared for January 1964, May 1969, May 1971, May 1973, May 1974, and for each May and September since 1975. Water-level data are collected in May and September each year to show the approximate annual low and high water-level conditions, respectively. Most of the water-level data for this map were collected by the U.S. Geological Survey during the period May 17-21, 2010. Supplemental water-level data were collected by other agencies and companies. Most water-level measurements were made during a 5-day period; therefore, measurements do not represent a 'snapshot' of conditions at a specific time, nor do they necessarily coincide with the seasonal low water-level condition.

Scientific Investigations Map↗
USGS2011

Potentiometric surface of the upper Floridan aquifer, west-central Florida, May 2011

The Floridan aquifer system consists of the Upper and Lower Floridan aquifers separated by the middle confining unit. The middle confining unit and the Lower Floridan aquifer in west-central Florida generally contain highly mineralized water. The water-bearing units containing freshwater are herein referred to as the Upper Floridan aquifer. The Upper Floridan aquifer is the principal source of water in the Southwest Florida Water Management District and is used for major public supply, domestic use, irrigation, and brackish water desalination in coastal communities (Southwest Florida Water Management District, 2000). This map report shows the potentiometric surface of the Upper Floridan aquifer measured in May 2011. The potentiometric surface is an imaginary surface connecting points of equal altitude to which water will rise in tightly-cased wells that tap a confined aquifer system (Lohman, 1979). This map represents water-level conditions near the end of the dry season, when groundwater levels usually are at an annual low and withdrawals for agricultural use typically are high. The cumulative average rainfall of 45.74 inches for west-central Florida (from June 2010 through May 2011) was 6.85 inches below the historical cumulative average of 52.59 inches (Southwest Florida Water Management District, 2011). Historical cumulative averages are calculated from regional rainfall summary reports (1915 to most recent complete calendar year) and are updated monthly by the Southwest Florida Water Management District. This report, prepared by the U.S. Geological Survey in cooperation with the Southwest Florida Water Management District, is part of a semi-annual series of Upper Floridan aquifer potentiometric-surface map reports for west-central Florida. Potentiometric-surface maps have been prepared for January 1964, May 1969, May 1971, May 1973, May 1974, and for each May and September from 1975 through 2010. Water-level data are collected in May and September each year to show the approximate annual low and high water-level conditions, respectively. Most of the water-level data for this map were collected by the U.S. Geological Survey during the period May 23-27, 2011. Supplemental water-level data were collected by other agencies and companies. Most water-level measurements were made during a 5-day period; therefore, measurements do not represent a "snapshot" of conditions at a specific time, nor do they necessarily coincide with the seasonal low water-level condition.

Florida↗
USGS2009

Water-level conditions in selected confined aquifers of the New Jersey and Delaware coastal plain, 2003

The Coastal Plain aquifers of New Jersey provide an important source of water for more than 2 million people. Steadily increasing withdrawals from the late 1800s to the early 1990s resulted in declining water levels and the formation of regional cones of depression. In addition to decreasing water supplies, declining water levels in the confined aquifers have led to reversals in natural hydraulic gradients that have, in some areas, induced the flow of saline water from surface-water bodies and adjacent aquifers to freshwater aquifers. In 1978, the U.S. Geological Survey began mapping the potentiometric surfaces of the major confined aquifers of New Jersey every 5 years in order to provide a regional assessment of ground-water conditions in multiple Coastal Plain aquifers concurrently. In 1988, mapping of selected potentiometric surfaces was extended into Delaware. During the fall of 2003, water levels measured in 967 wells in New Jersey, Pennsylvania, northeastern Delaware, and northwestern Maryland were used estimate the potentiometric surface of the principal confined aquifers in the Coastal Plain of New Jersey and five equivalent aquifers in Delaware. Potentiometric-surface maps and hydrogeologic sections were prepared for the confined Cohansey aquifer of Cape May County, the Rio Grande water-bearing zone, the Atlantic City 800-foot sand, the Vincentown aquifer, and the Englishtown aquifer system in New Jersey, as well as for the Piney Point aquifer, the Wenonah-Mount Laurel aquifer, and the Upper Potomac-Raritan-Magothy, the Middle and undifferentiated Potomac-Raritan-Magothy, and the Lower Potomac-Raritan-Magothy aquifers in New Jersey and their equivalents in Delaware. From 1998 to 2003, water levels in many Coastal Plain aquifers in New Jersey remained stable or had recovered, but in some areas, water levels continued to decline as a result of pumping. In the Cohansey aquifer in Cape May County, water levels near the center of the cone of depression underlying the southern part of the peninsula remained about the same as in 1998. To the south, recoveries up to 8 feet were observed in southern Lower Township as withdrawals had decreased since 1998. In the northern part of Cape May County, water levels had not changed substantially from historic conditions. In the Rio Grande water-bearing zone, water levels rose by as much as 13 ft at the Rio Grande well field; elsewhere across the aquifer, little change had occurred. In the Atlantic City 800-foot sand, water-level changes were greatest in southern Cape May County; at the Cape May desalination wells, water levels were as much as 32 ft lower in 2003 than in 1998. In contrast, water levels at the center of a regional cone of depression near Atlantic City rose by as much as 10 ft. Within the Piney Point aquifer water levels rose by 46 ft near Seaside Park. Similarly, water levels increased by more than 30 ft in and around the major cone of depression underlying Dover, Delaware. In the Vincentown aquifer, water levels stabilized or recovered by 2 ft to 6 ft from 1998 to 2003 in most of the wells measured; the exception is near Adelphia in Monmouth County, where water levels rose by as much as 18 ft. From 1998 to 2003, water levels near the center of a large cone of depression that extends from Monmouth to Ocean County recovered by as much as 20 ft in the Wenonah-Mount Laurel aquifer. Concurrently, ground-water levels within the Englishtown aquifer system declined by as much as 13 ft in the same area. Water levels across much of the Upper Potomac-Raritan-Magothy aquifer in the northern Coastal Plain remained about the same as 5 years previous, except in northern Ocean County where ground-water levels declined 10 ft to 33 ft. Water levels in the Middle Potomac-Raritan-Magothy aquifer declined from 5 to 9 ft along the border between Monmouth and Middlesex County. Elsewhere, across the northern part of the Coastal Plain, water levels stabilized within the Cretaceous-a

Delaware, New Jersey↗
USGS2009

Future water-supply scenarios, Cape May County, New Jersey, 2003-2050

Stewards of the water supply in New Jersey are interested in developing a plan to supply potable and non-potable water to residents and businesses of Cape May County until at least 2050. The ideal plan would meet projected demands and minimize adverse effects on currently used sources of potable, non-potable, and ecological water supplies. This report documents past and projected potable, non-potable, and ecological water-supply demands. Past and ongoing adverse effects to production and domestic wells caused by withdrawals include saltwater intrusion and water-level declines in the freshwater aquifers. Adverse effects on the ecological water supplies caused by groundwater withdrawals include premature drying of seasonal wetlands, delayed recovery of water levels in the water-table aquifer, and reduced streamflow. To predict the effects of future actions on the water supplies, three baseline and six future scenarios were created and simulated. Baseline Scenarios 1, 2, and 3 represent withdrawals using existing wells projected until 2050. Baseline Scenario 1 represents average 1998-2003 withdrawals, and Scenario 2 represents New Jersey Department of Environmental Protection (NJDEP) full allocation withdrawals. These withdrawals do not meet projected future water demands. Baseline Scenario 3 represents the estimated full build-out water demands. Results of simulations of the three baseline scenarios indicate that saltwater would intrude into the Cohansey aquifer as much as 7,100 feet (ft) to adversely affect production wells used by Lower Township and the Wildwoods, as well as some other near-shore domestic wells; water-level altitudes in the Atlantic City 800-foot sand would decline to -156 ft; base flow in streams would be depleted by 0 to 26 percent; and water levels in the water-table aquifer would decline as much as 0.7ft. [Specific water-level altitudes, land-surface altitudes, and present sea level when used in this report are referenced to the North American Vertical Datum of 1988 (NAVD 88).] Future scenarios 4 to 9 represent withdrawals and the effects on the water supply while using estimated full build-out water demands. In most townships, existing wells would be used for withdrawals in the simulation. However, in Lower and Middle Townships, the Wildwoods, and the Cape Mays, withdrawals from some wells would be terminated, reduced, or increased. Depending on the scenario, proposed production wells would be installed in locations far from the saltwater fronts, in deep freshwater aquifers, in deeper saltwater aquifers, or proposed injection wells would be installed to inject reused water to create a freshwater barrier to saltwater intrusion. Simulations indicate that future Scenarios 4 to 9 would reduce many of the adverse effects of Scenarios 1, 2, and 3. No future scenario will minimize all adverse impacts. In Scenario 4, Lower Township would drill two production wells in the Cohansey aquifer farther from the Delaware shoreline than existing wells and reduce withdrawals from wells near the shoreline. Wildwood Water Utility (WWU) would reduce withdrawals from existing wells in the Cohansey aquifer and increase withdrawals from wells in the Rio Grande water-bearing zone. Results of the simulation indicate that saltwater intrusion and ecological-water supply problems would be reduced but not as much as in Scenarios 5, 7, 8, and 9. In Scenario 5, the Wildwoods and Lower Township each would install a desalination plant and drill two wells to withdraw saltwater from the Atlantic City 800-foot sand. Saltwater intrusion problems would be reduced to the greatest extent with this scenario. Ecological water supplies remain constant or decline from 2003 baseline values. Water-level altitudes would decline to -193 ft in the Atlantic City 800-foot sand, the deepest potentiometric level for all scenarios. In Scenario 6, Lower Township would build a tertiary treatment system and drill three wells open to the Cohanse

New Jersey↗
USGS2012

Characterization of the hydrologic resources of San Miguel County, New Mexico, and identification of hydrologic data gaps, 2011

The U.S. Geological Survey (USGS), in cooperation with San Miguel County, New Mexico, conducted a study to assess publicly available information regarding the hydrologic resources of San Miguel County and to identify data gaps in that information and hydrologic information that could aid in the management of available water resources. The USGS operates four continuous annual streamgages in San Miguel County. Monthly discharge at these streamgages is generally bimodally distributed, with most runoff corresponding to spring runoff and to summer monsoonal rains. Data compiled since 1951 on the geology and groundwater resources of San Miguel County are generally consistent with the original characterization of depth and availability of groundwater resources and of source aquifers. Subsequent exploratory drilling identified deep available groundwater in some locations. Most current (2011) development of groundwater resources is in western San Miguel County, particularly in the vicinity of El Creston hogback, the hogback ridge just west of Las Vegas, where USGS groundwater-monitoring wells indicate that groundwater levels are declining. Regarding future studies to address identified data gaps, the ability to evaluate and quantify surface-water resources, both as runoff and as potential groundwater recharge, could be enhanced by expanding the network of streamgages and groundwater-monitoring wells throughout the county. A series of seepage surveys along the lengths of the rivers could help to determine locations of surface-water losses to and gains from the local groundwater system and could help to quantify the component of streamflow attributable to irrigation return flow; associated synoptic water-quality sampling could help to identify potential effects to water quality attributable to irrigation return flow. Effects of groundwater withdrawals on streamflow could be assessed by constructing monitoring wells along transects between production wells and stream reaches of interest to monitor decline or recovery of the water table, to quantify the timing and extent of water-table response, and to identify the spatial extent of capture zones. Assessment of groundwater potential could be aided by a county-wide distribution of water-level information and by a series of maps of groundwater potential, compiled for each individual aquifer, including saline aquifers, for which the potential for municipal use through desalination could be explored. A county-wide geographic information system hydrologic geodatabase could provide a comprehensive picture of water use in San Miguel County and could be used by San Miguel County as a decision-support tool for future management decisions.

New Mexico↗
USGS2014

Description of landscape features, summary of existing hydrologic data, and identification of data gaps for the Osage Nation, northeastern Oklahoma, 1890-2012

The Osage Nation of northeastern Oklahoma, conterminous with Osage County, is characterized by gently rolling uplands and incised stream valleys that have downcut into underlying sedimentary rock units of Pennsylvanian through Permian age. Cattle ranching and petroleum and natural-gas extraction are the principal land uses in this rural area. Freshwater resources in the Osage Nation include water flowing in the Arkansas River and several smaller streams, water stored in several lakes, and groundwater contained in unconsolidated alluvial aquifers and bedrock aquifers. The Vamoosa-Ada aquifer is the primary source of fresh groundwater in this area. Fresh groundwater is underlain by saline groundwater in aquifers underlying the Osage Nation. Because of the potential for future population increases, demands for water from neighboring areas such as the Tulsa metropolitan area, and expansion of petroleum and natural-gas extraction on water resources of this area, the U.S. Geological Survey, in cooperation with the Osage Nation, summarized existing hydrologic data and identified data gaps to provide information for planning of future development of water resources in the Osage Nation. Streamflows in the Osage Nation are substantially affected by precipitation. During the relatively wet periods from the 1970s to 2000, the annual streamflows in the Osage Nation increased by as much as a factor of 2 relative to preceding decades, with subsequent decreases in streamflow of as much as 50 percent being recorded during intermittent drier years of the early 2000s. This report summarizes hydrologic data from 3 surface-water sites and 91 wells distributed across the Osage Nation. Data collected at those sites indicate that surface water in the Osage Nation generally has sufficient dissolved oxygen for survival of both coldwater and warmwater aquatic biota. Total dissolved solids concentration exceeded the secondary drinking-water standard of 500 milligrams per liter (mg/L) in up to 75 percent of the surface-water samples, indicating limited availability of potable water at some sites. Some surface-water samples collected in the Osage Nation contained dissolved chloride concentrations exceeding the secondary drinking-water standard of 250 mg/L, with greater chloride concentrations in selected basins appearing to be associated with greater densities of petroleum well locations. Several lakes sampled in the Osage Nation from 2011–12 contained sufficient chlorophyll-a concentrations to be ranked as mesotrophic to eutrophic, indicating impairment by nutrients. Relatively large dissolved phosphorus concentrations in many surface-water samples, compared to water-quality standards, indicate that eutrophication can occur in local streams and lakes. The amount of fresh groundwater stored in alluvial aquifers and the Vamoosa-Ada bedrock aquifer is adequate for domestic and other purposes in the Osage Nation at the current rate of usage. In areas where these aquifers are absent, groundwater must be pumped from minor bedrock aquifers that produce smaller volumes of water. About 30 and 60 percent of 32 and 54 water samples collected from the alluvial and Vamoosa-Ada aquifers, respectively, contained total dissolved solids concentrations larger than the secondary drinking-water standard of 500 mg/L. Local factors, such as natural seepage of brines or leakage from petroleum and natural-gas extraction activities, may cause substantial variations in dissolved chloride concentration in groundwater in the Osage Nation. Total phosphorus concentrations measured in groundwater samples were similar to dissolved phosphorus concentrations measured in the base flow of several streams. Total fresh surface-water withdrawals (use) and fresh groundwater withdrawals in the Osage Nation were estimated to have increased from 0.75 to 16.19 million gallons per day and from 0.13 to 2.39 million gallons per day, respectively, over the period from 1890 through 2010. Estimated saline-groundwater reinjection volumes at the heavily developed Burbank Oil Field in the Osage Nation from 1950 through 2012 were many times larger than the total amounts of freshwater withdrawn in this area, with estimated increases in saline-groundwater reinjection in the 2000s probably being related to increased petroleum extraction. Estimates of freshwater resources in local streams, lakes, and freshwater aquifers and of net annual precipitation indicate that less than 1 percent of freshwater resources and net annual precipitation currently is being withdrawn annually in the Osage Nation. In addition to freshwater resources, the Osage Nation may be underlain by 45,000,000 million gallons of brines, a small portion of which are withdrawn and reinjected during petroleum and natural-gas extraction. Ongoing development of desalinization technology may lead to the ability to expand use of these saline waters in the future. Several additional studies could improve understanding of the hydrologic resources of the Osage Nation. Development of computer models (simulations) of groundwater and surface-water flow for this area could enable testing of scenarios of localized and widespread effects of future climate variations and water-use changes on streamflows, lake-water levels, and groundwater levels in the Osage Nation. Installation of additional long-term streamflow and water-quality sampling stations, some with continuous water-quality monitors, could expand and improve understanding of surface-water quality. Periodic measurement of groundwater levels and sampling of water from a network of wells could provide better information about trends of groundwater quantity and quality with time. Measurement of water withdrawals at selected sites could enable more accurate estimates of water use. Lastly, better understanding of aquifer properties and spatial distribution of saline groundwater provided by geophysical surveys could improve understanding of fresh and saline groundwater resources underlying the Osage Nation.

Oklahoma↗
USGS2018

Effects of groundwater withdrawals from the Hurricane Fault zone on discharge of saline water from Pah Tempe Springs, Washington County, Utah

Pah Tempe Springs, located in Washington County, Utah, contribute about 95,000 tons of dissolved solids annually along a 1,500-foot gaining reach of the Virgin River. The river gains more than 10 cubic feet per second along the reach as thermal, saline springwater discharges from dozens of orifices located along the riverbed and above the river on both banks. The spring complex discharges from fractured Permian Toroweap Limestone where the river crosses the north-south trending Hurricane Fault. The Bureau of Reclamation Colorado River Basin Salinity Control Program is evaluating the feasibility of capturing and desalinizing the discharge of Pah Tempe Springs to improve downstream water quality in the Virgin River. The most viable plan, identified by the Bureau of Reclamation in early studies, is to capture spring discharge by pumping thermal groundwater from within the Hurricane Fault footwall damage zone and to treat this water prior to returning it to the river. Three multiple-day interference tests were conducted between November 2013 and November 2014, wherein thermal groundwater was pumped from fractured carbonate rock in the fault damage zone at rates of up to 7 cubic feet per second. Pumping periods for these tests lasted approximately 66, 74, and 67 hours, respectively, and the tests occurred with controlled streamflows of approximately 2.0, 3.5, and 24.5 cubic feet per second, respectively, in the Virgin River upstream from the springs reach. Specific conductance, water temperature, and discharge were monitored continuously in the river (upstream and downstream of the springs reach) at selected individual springs, and in the pumping discharge during each of the tests. Water levels were monitored in three observation wells screened in the thermal system. Periodic stream and groundwater samples were analyzed for dissolved-solids concentration and the stable isotopes of oxygen and hydrogen. Additional discrete measurements of field parameters (specific conductance, water temperature, pH, and discharge) were made at up to 26 sites along the springs reach. These data demonstrate the interaction between the saline, thermal groundwater system and the Virgin River, and provide estimates of reductions in dissolved-solids loads to the river. The interference tests show that pumping thermal groundwater from the shallow carbonate aquifer adjacent to the springs is effective at capturing high dissolved-solids loads discharging from Pah Tempe Springs before they enter the Virgin River. Discharge measurements made in the Virgin River downstream of the springs reach show that streamflow is reduced by approximately the amount pumped, indicating that complete capture of thermal discharge is possible. During the February 2014 test, the dissolved-solids load removed by pumping (190 tons per day) was approximately equal to the dissolved-solids load reduction observed in the river below the springs reach, indicating near 100-percent efficient capture of spring-sourced dissolved solids. However, an observed decrease in temperature and specific conductance of the pumping discharge during the high-flow test in November 2014 showed that capture of the cool, fresh river water can occur and is more likely at a higher stage in the Virgin River.

Utah↗
USGS2018

Santa Barbara and Foothill groundwater basins Geohydrology and optimal water resources management—Developed using density dependent solute transport and optimization models

Groundwater has been a part of the city of Santa Barbara’s water-supply portfolio since the 1800s; however, since the 1960s, the majority of the city’s water has come from local surface water, and the remainder has come from groundwater, State Water Project, recycled water, increased water conservation, and as needed, seawater desalination. Although groundwater from the Santa Barbara and Foothill groundwater basins only accounts for a small percentage of the long-term supply, it is an important source of supplemental water during times of surface-water shortages. During the late 1980s and early 1990s, production wells extracted additional groundwater to compensate for drought related water-delivery shortfalls from other sources; in response, water levels declined substantially in the Santa Barbara and Foothill groundwater basins (below sea level in the Santa Barbara groundwater basin). In coastal basins that have groundwater extraction near shore, seawater intrusion is often a problem. Seawater intrusion in the Santa Barbara groundwater basin is thought to be more limited than in other coastal basins because of an offshore fault that acts as a partial barrier to groundwater flow. During the late 1980s and early 1990s, seawater intrusion was observed in the Santa Barbara groundwater basin, as indicated by increased chloride concentrations at several monitoring wells that ranged from 200 ft to 1,300 ft from the ocean and as close as 2,900 ft to the nearest pumping well. This demonstrated that seawater can intrude into the Santa Barbara groundwater basin when groundwater levels fall below sea level near the coast. The city of Santa Barbara is interested in developing a better understanding of the sustainability of its groundwater supplies. In 2014, California adopted historic legislation to manage its groundwater: the Sustainable Groundwater Management Act (SGMA). The SGMA requires the development and implementation of “Groundwater Sustainability Plans” in 127 priority groundwater basins; although Santa Barbara was not a designated priority basin, the city is taking steps to achieve sustainability. Sustainability was defined in the SGMA in terms of avoiding undesirable results: significant and unreasonable groundwater-level declines, reduction in groundwater storage, seawater intrusion, water-quality degradation, land subsidence, and surface-water depletion. In this project, a cooperative study between the U.S. Geological Survey (USGS) and the city of Santa Barbara, sustainable yield is defined as the volume of groundwater that can be pumped from storage without causing water-level drawdowns and the associated increases in seawater intrusion (as indicated by increases in measured chloride concentrations) at selected wells. In order to estimate the sustainability of Santa Barbara’s groundwater basins, a three-dimensional density-dependent groundwater-flow and solute-transport model (the Santa Barbara Flow and Transport Model, or SBFTM) was developed on the basis of an existing groundwater-flow model. To simulate seawater intrusion to the Santa Barbara Basin under various management strategies, the SBFTM uses the USGS code SEAWAT to simulate salinity transport and variable-density flow. The completed SBFTM was coupled with a management optimization tool, in this case a multi-objective evolutionary algorithm, to determine optimal pumping strategies that maximize the sustainable yield and at the same time satisfy user-defined drawdown and chloride-concentration constraints. As part of this study, a three-dimensional hydrogeologic framework model was developed to quantify the extent and hydrogeologic characteristics of the Santa Barbara and Foothill groundwater basins and to help define the discretization and hydraulic properties used in the SBFTM. The development of the hydrogeologic framework model required the collection and reconciliation of geologic and geophysical data from existing maps, reports, and databases, along with geologic and hydrologic data from recently drilled wells. These data were integrated into a three-dimensional hydrogeologic framework model that defines the stratigraphy and geometry of the aquifer zones and the major geologic structures in the basin. The hydrogeologic framework model also quantifies the variation in sediment grain size within each aquifer zone as the percentage of coarse-grained sediment. Previous studies indicated that there are two principal water-producing zones in the Santa Barbara groundwater basin, the upper and lower producing zones; an additional thin, productive zone was identified as part of this study. This “middle producing zone” is not as areally extensive as the upper and lower producing zones and only exists in the coastal part of Storage Unit I. These producing zones are bounded at depth by less productive shallow, middle, and deep zones. Two versions of the SBFTM were constructed: an initial-condition model and a modern transient model. The initial-condition model is a long-term transient model that simulates flow and solute-transport conditions during a period with limited anthropogenic influences preceeding the modern transient model. The simulation-transient model simulates flow and transport conditions from 1929 through 2013; however, because of data availability, the focus of the model calibration was 1972–2013. The SBFTM was calibrated to measured groundwater levels and drawdown, as well as measured chloride concentrations and change in concentrations, using a combination of automated and trial-and-error parameter-estimation techniques. A sensitivity analysis indicated that, in general, the SBFTM was most sensitive to recharge- and pumping-distribution parameters, specifically those controlling the amount of small-catchment recharge and the distribution of water extraction by hydrogeologic layer for production wells. The model was also sensitive to parameters controlling stream-recharge rates, horizontal and vertical hydraulic conductivity, and porosity. From 1929 to 1971, most of the water entering the area represented by the SBFTM was from creek and small-catchment recharge, and the majority of water leaving the SBFTM area was from pumping, discharge to creeks, and drains. In addition, about 37 percent of the total pumpage came from a net reduction in groundwater storage. From 1972 to 2013, the amount of water entering and leaving the SBFTM was fairly similar as that from 1929 to 1971, except the reduction in pumpage added about 17,000 acre-ft of water to storage. During this later period, there were also times of storage loss. For example, during July 1990, a month when approximately 705 acre-ft of groundwater was pumped in the study area, the pumpage was much greater than all sources of recharge combined, and about 382 acre-ft of water was removed from groundwater storage. Simulated hydraulic heads replicated the observed data to an acceptable matching of the measured water-level, flow direction, and vertical gradients. Simulated hydrographs for selected wells were in good agreement with the measured data, with an average residual of -2.7 ft and a standard deviation of 14.5 ft, indicating that the simulated heads, on average, underestimated the observed water levels. An examination of the model fit indicated that most of the discrepancies were lower simulated heads at wells proximal to production well sites. The simulated chloride concentrations reasonably matched the rising limbs of the measured breakthrough curves in terms of timing and magnitude; however, the simulation overestimated the chloride concentrations on the falling limbs. The overestimation of low chloride concentrations was attributed to the model overestimating the advance of the chloride front during periods of heavy pumping and underestimating the retreat of the chloride front during periods of low pumping. These simulation errors would result in a conservative response by local water managers to seawater intrusion. The SBFTM was used to develop a collection of predictive simulations optimized to produce pumping schedules that maximize yield, subject to a set of constraints and competing objectives. The simulations were grouped as scenarios that differed in their time horizon, initial conditions for groundwater levels and chloride concentrations, as well as precipitation, which was incorporated into the model through simulated recharge. Overall, five scenarios were developed in a multi-objective framework to obtain optimal pumping rates for all of the wells managed by the city, while minimizing excessive drawdown and seawater intrusion. For the current study, complexities in the simulation model and the optimization formulation required additional considerations. Incorporating the solute-transport equations to simulate chloride transport added a highly nonlinear process that is solved iteratively in each time step of the groundwater-flow model. These nonlinearities, coupled with the highly refined grid in the current model, creates challenges for many traditional optimization methods. Therefore, an optimization method was needed that could address nonlinear relationships as well as a very large problem size. Lastly, the optimization problem was reformulated to include multiple objectives without requiring convergence to a single solution. This approach, guided by the city’s objectives, allowed the maximum extraction of information from the complex simulation. Borg, a multi-objective evolutionary algorithm, was chosen as the optimization algorithm for this study for several reasons: (1) it is very computationally efficient; (2) it can run in parallel; (3) it requires little user input; and (4) it can solve for multiple competing objectives. The first three points allow the algorithm to proceed toward the optimal solutions at the fastest possible rate. The fourth point is advantageous for large, complex optimization problems because it is difficult to formulate the optimization problem in a way that produces only one optimal solution. The problem formulation consisted of four competing objectives and a constraint set in accordance with the main concerns of the city. The objectives were maximizing total pumpage, minimizing seawater intrusion, minimizing total drawdown in production wells, and minimizing the maximum drawdown. The constraints were pump capacity, meeting drinking-water standards for chloride, maintaining a specified minimum flowrate to a groundwater treatment plant, and maintaining minimum water levels in pumping wells. The decision variables either were quarterly pumpage by well or total pumpage by basin. Five optimization scenarios were developed that allow the decision makers to evaluate a range of optimal solutions for a variety of water levels and chloride concentrations as well as potential future climatic conditions. Three scenarios (1, 2, and 5) were multi-objective optimization formulations that allowed for variations in management preferences and climatic conditions. The other two scenarios (3 and 4) were designed to examine the optimization results to answer specific questions. Scenario 1 described the best-case sustainable yield assuming a “full” basin (that is, high initial water levels) and typical climate conditions for 10 years. Scenario 2 also started with a “full” basin; however, this was followed by a 10-year drought. Scenario 3 determined if an “empty” basin (that is, low initial water levels) would recover to full conditions (1998 conditions) given climate assumptions and optimal pumping schedules from scenarios 1 and 2. Scenario 4 was designed to produce decision rules that can be used by water managers to help choose an optimal pumping schedule based on measured water-level or chloride data. Scenario 5 identified future pumping schedules based on short-term climate variations during a 2-year management horizon. The results from scenarios 1 and 2 described the differences in maximum pumpage in the basin under typical and dry long-term climate projections, respectively. The scenario 1 results indicated the maximum 10-year pumpage of the basin was about 31,300 acre-ft under typical conditions and controlling simulated seawater intrusion and drawdowns. For scenario 2, less recharge over the 10-year dry climate produced a maximum pumpage estimate of 30,000 acre-ft to control seawater intrusion and drawdowns. The larger pumpage for scenario 1 resulted in more seawater intrusion, but less total drawdown, compared to that of scenario 2. Results for scenarios 3 and 4 showed the basin’s response to management actions combined with climate projections. Both scenarios used the optimal pumping schedules and the 10-year climates from scenarios 1 and 2. The scenario 3 results showed that under minimal pumping, the basin did not fully recover to 1998 water levels within 10 years under either climate scenario. The relatively larger recharge from the typical climate resulted in less drawdown at coastal monitoring wells after the 10-year recovery period than that from the dry climate. The location of the seawater intrusion front was not appreciably different between the scenarios, however. Scenario 4 used the optimal results from scenarios 1 and 2 to produce decision-rule curves that illustrated the pumpage for each basin, given measured levels of chloride concentration or drawdown. This allowed the use of additional measurements at monitoring wells to assess future management decisions on the basis of the sensitivity of observations of drawdown and seawater intrusion to various pumping rates. Scenario 5 allowed managers to investigate the effects of short-term climate variations on optimal pumping schedules. Three specific 2-year simulations were optimized: typical-to-dry (scenario 5A), dry-to-typical (scenario 5B), and dry-to-dry (scenario 5C). The most noteable result from scenario 5 was the overall reduction in optimal pumpage for most schedules in scenario 5C, when the climate is simulated as dry-to-dry. There are also many optimal pumping schedules that produced an overall increase in waterlevels over the two-year simulation period, regardless of climatic condition. Similar to scenario 2, the scenario 5C results represents conservative yield estimates under a minimal-precipitation climatic condition.

California↗
USGS1977

Public water supplies of selected municipalities in Florida, 1975

In 1975, the 169 municipalities and 5 county water systems listed in this report supplied 1.037 million gallons of water each day, on the average to 77 percent of the population of the State of Florida. The quantity of water supplied represented 90 percent of the State's public water supply demand. Of the 169 municipalities and 5 county systems, 150 supplied 887 million gallons of ground water and 24 supplied 150 million gallons of surface water each day, on the average, representing 85 percent and 15 percent, respectively, of the total demand of the 174 water systems. Three of the 150 municipal ground-water suppliers are reported to have processed, that year, about 3.2 million gallons of water each day by desalination.

Florida↗
USGS1992

Factors that affect public-supply water use in Florida, with a section on projected water use to the year 2020

Public-supply water use in Florida increased 242 percent between 1960 and 1987 from 530 Mgal/d (million gallons per day) to 1,811 Mgal/d. This change is primarily a result of increases in population and tourism since 1960. Public-supply utilities provide water to a variety of users. In 1985, 71 percent of the water used for public supply was delivered for residential uses, 15 percent for commercial uses, 9 percent for industrial uses, and the remaining 5 percent for public use or other uses. Residential use of public-supply water in Florida has increased nearly 280 Mgal/d, but has decreased in the proportion of total deliveries from 80 to 71 percent between 1975 and 1985. This trend resulted from increased tourism and related commercial services associated with population and visitors. One of several factors that influences public-supply water use in Florida is the increase in resident population, which increased from 4.95 million in 1960 to more than 12.0 million in 1987. Additionally, Florida's nonresident population increased from 18.8 million visitors in 1977, to 34.1 million visitors in 1987, and the part of Florida's population that relies on public-supply water increased from 68 percent in 1960, to 86 percent in 1987. The public supply per capita use was multiplied by the projected populations for each county for the years 2000, 2010, and 2020 to forecast public-supply water use. Using medium projections, Florida?s population is expected to increase to nearly 16 million in the year 2000, to 18 million in the year 2010, and to almost 20 million in the year 2020, of which an estimated 13.5 million people will be supplied water from public-supply water systems in the year 2000, 15 million in 2010, and nearly 17 million by the year 2020. Public-supply water use is expected to increase to a projected (medium) 2,310 Mgal/d in the year 2000, 2,610 Mgal/d in the year 2010, and 2,890 Mgal/d in the year 2020. If the population exceeds the medium projections for the years 2000, 2010, and 2020, high projections estimate public-supply water use could reach 2,570 Mgal/d in 2000, 3,210 Mgal/d in 2010, and 3,900 Mgal/d in 2020. Palm Beach County is projected to have the largest increase in public-supply water use, from 168 Mgal/d used in 1987 to a medium projected 338 Mgal/d for 2020. Dade County's public-supply water use is projected (medium) to increase to nearly 471 Mgal/d for 2020, the largest county use in Florida. Water demand options, such as conservation, restrictions, education programs, leak detection and repair programs, and more realistic pricing practices can reduce the demand for freshwater. Increased use of alternative sources of water, such as reclaimed wastewater and desalinated seawater also can reduce the demand for freshwater. Because the water demand projections in this report are based primarily on population projections, they should represent an upper limit of actual future demand if the population projections prove sound. Any additional water demand options implemented in the future at the State, county, or public-supply facility level may significantly reduce per capita use and result in public-supply use less than projected in this report.

Florida↗