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At least 1,117 records · Page 62Linked to original sources

USGS1977

Water resources data for California, water year 1976; Volume 2: Pacific Slope basins from Arroyo Grande to Oregon State line except Central Valley

Water-resources data for the 1976 water year for California consist of records of stage, discharge, and water quality of streams; stage, contents, and water quality of lakes and reservoirs; records of water levels in selected observation wells; and selected chemical analyses of ground water. Records for a few pertinent streamflow and water-quality stations in bordering States are also included. The records were collected and computed by the Water Resources Division of the U.S. Geological Survey under the direction of Lee R. Peterson, district chief; Winchell Smith, assistant district chief for hydrologic data; and Leonard N. Jorgensen, chief of the basic-data section. These data, a contribution to the National Water Data System, were collected by the Geological Survey and cooperating local, State, and Federal agencies in California.

California↗

USGS1977

Water resources data for California, water year 1976; Volume 3, Southern Central Valley basins and the Great Basin from Walker River to Truckee River

California↗

USGS1978

Water resources data for California, water year 1977; Volume 1: Colorado River Basin, Southern Great Basin from Mexican Border to Mono Lake Basin, and Pacific Slope Basins from Tijuana River to Santa Maria River

Water-resources data for the 1977 water year for California consist of records of stage, discharge, and water quality of streams; stage, contents, and water quality of lakes and reservoirs; records of water levels in selected observation wells; and selected chemical analyses of ground water. Records for a few pertinent streamflow and water-quality stations in bordering States are also included. The records were collected and computed by the Water Resources Division of the U.S. Geological Survey under the direction of Winchell Smith, Assistant District Chief for Hydrologic Data and Leonard N. Jorgensen, Chief of the Basic-Data Section. These data, a contribution to the National Water Data System, were collected by the Geological Survey and cooperating local, State, and Federal agencies in California.

California↗

USGS1978

Water resources data for California, water year 1977; Volume 4: Northern Central Valley basins and the Great Basin from Honey Lake basin to Oregon state line

California↗

USGS2000

Ground-water resources of Tinian, Commonwealth of the Northern Mariana Islands

Tinian, which lies in the western Pacific Ocean at latitude 15°N and longitude 145°W (fig. 1), is the second largest island (39.2 mi 2 ) in the Commonwealth of the Northern Mariana Islands (CNMI). Fresh ground water is obtained from shallow wells that tap the surface of a freshwater lends found in an aquifer composed mainly of coralline limestone. The main water-supply well withdraws water with a chloride concentration ranging from 160 to 220 mg/L. Current (1999) pumping rates adequately supply the island residents but future demand are expected to be higher.. To better understand the ground-water resources of the island and to learn more about the hydrology of oceanic islands, the U.S. Geological Survey (USGS) entered into a cooperative study with the Municipality of Tinian. The objective of the study, conducted between 1990 and 1997, was to assess the ground-water resources of the is;land. This report presents some of the results of the study including a description of the island's geology and geography, the current land use, the water-production system, the thickness and arcal extent of the freshwater lens, the water-table configuration and directions of ground-water flow. The report also discusses the relation of the changes in water-table elevation to daily and seasonal changes in ocean level.

Tinian Island↗

USGS2000

Water-resources-related information for the St. Croix Reservation and vicinity, Wisconsin

The St. Croix Chippewa Tribe is interested in documenting water-quality conditions in lakes and streams adjacent to their Reservation lands in northwestern Wisconsin and developing management plans to protect these water resources. This report provides the Tribe with a retrospective summary and analysis of available water-resources-related information for their Reservation and vicinity. The study area is divided into four main watersheds: Big Round Lake, Clam River at Clam Lake Outlet, Yellow River at Danbury, and Loon Creek at Danbury. The Clam River Watershed includes the subwatersheds of Bashaw and Sand Lakes. The Yellow River Watershed includes the subwatersheds of Big Sand and Gaslyn Lakes. In all, 41 surface-water studies or reports that include information relevant to the study area were identified. Most of the surface-water studies were regional or statewide summaries. Fifteen of these studies include lake information and 36 include stream information. Twenty-eight of the studies include water-quality data and 16 include information describing aquatic biology. Water- and sediment-quality data were obtained for 80 lakes and 23 streams in the study area. Lake information includes data for 101 water-quality characteristics from nearly 4,300 water and sediment analyses of samples collected between 1972 and 1998. Stream information summarized in this report includes data for 135 water-quality characteristics and nearly 4,500 water and sediment analyses of samples collected at 23 sites between 1964 and 1999. A total of 41 ground-water studies or reports that include information relevant to the study area were identified. Most of the ground-water studies were regional or statewide summaries. Of the 41 studies, 33 include water-quality information, 9 include information regarding water use, and 23 provide descriptions of geology and aquifer characteristics relevant to the study area. Water-quality information for 773 wells was compiled. Most of the sampled wells were used for drinking water, and most of the drinking-water wells represent domestic supplies. Water-quality data summarized in this report represent 270 characteristics and more than 10,300 analyses of samples collected from drinking-water wells between 1911 and 1999; however, most of the water-quality data were collected after about 1990.

Wisconsin↗

USGS2001

Hydrogeology and water quality of five principal aquifers in the Lower Platte South Natural Resources District, eastern Nebraska, 1994

The U.S. Geological Survey, in cooperation with the Lower Platte South Natural Resources District, conducted a hydrogeologic and water-quality reconnaissance study of the five principal aquifers in deposits of Quaternary age in the Natural Resources District. The purpose of the study was to delineate the approximate extent of the aquifers, to estimate volumes of drainable water in three aquifers, to provide information that could be useful in designing future ground-water-quality monitoring, and to determine baseline water-quality conditions in the aquifers, focusing on nitrate concentrations. The approximate lateral boundaries of the Dwight-Valparaiso, Crete-Princeton-Adams, and Waverly aquifers were defined as areas in which the thickness of continuous sand and gravel deposits was less than 40 feet. The three aquifers were determined to contain about 1,340,000; 1,540,000; and 172,000 acre-feet of drainable water, respectively, assuming a specific yield of 0.20. During the summer of 1994, ground-water samples were collected from 46 wells in the five aquifers and analyzed for nitrate and screened for triazine herbicides. Additionally, water samples from 39 of these wells were analyzed for major ions, iron, and manganese, and 35 were analyzed for radon. Water-quality analyses revealed that the water in the five aquifers had specific conductances that ranged from 399 to 2,040 micro-siemens per centimeter and was a calcium-carbonate to calcium-magnesium-sodium carbonate type. The most mineralized water samples were from the Crete-Princeton-Adams aquifer, which contained a median concentration of dissolved solids of 520 milligrams per liter. Concentrations of nitrate in water samples from the aquifers ranged from less than 0.05 to 23 milligrams per liter as nitrogen, and only six water samples exceeded the Maximum Contaminant Level established by the U.S. Environmental Protection Agency of 10 milligrams per liter. The median concentration of radon for water samples from the five aquifers was 300 picocuries per liter, which is the proposed Maximum Contaminant Level. Water samples from the Crete-Princeton-Adams and Waverly aquifers had the largest concentrations of radon among the five aquifers. The Crete-Princeton-Adams aquifer had a median concentration of 440 picocuries per liter, and the Waverly aquifer had a median concentration of 390 picocuries per liter. Herbicides were detected in water from only six wells, which were in four of the five aquifers. Atrazine, metabolites of atrazine, metolachlor, and metribuzin were detected in concentrations generally less than 1.00 microgram per liter.

Water-Resources Investigations Report↗

USGS2002

Ground-water resources of the Clifton Park area, Saratoga County, New York

Ground water is the sole source of public water supply for Clifton Park, a growing suburban community north of Albany, New York. Increasing water demand, coupled with concerns over ground-water quantity and quality, led the Clifton Park Water Authority in 1995 to initiate a cooperative study with the U.S. Geological Survey to update and refine the understanding of ground-water resources in the area. Ground-water resources are largely associated with three aquifers in the eastern half of the area. These aquifers overlie or encompass the Colonie Channel, a north-south-oriented bedrock channel that is filled primarily with lacustrine glacial deposits. The three aquifers are: (1) an unconfined lacustrine sand aquifer, (2) the Colonie Channel aquifer, which is confined within the deepest parts of the channel and variably confined and unconfined within the shallower, peripheral channel areas, and (3) an unconfined alluvial aquifer beneath the Mohawk River flood plain, which represents the southern limit of the study area. The lacustrine sand aquifer has little potential for large-scale withdrawals because it is predominantly fine grained and is susceptible to contamination from human activities at land surface. Water from this aquifer can, however, recharge the underlying peripheral parts of the Colonie Channel aquifer where hydraulic connections are present. The Colonie Channel aquifer consists of thin sand and gravel and (or) shallow, fractured bedrock over much of the channel area; discontinuous deposits of thicker (more than 20 feet) sand and gravel are common in the peripheral channel areas. The deepest, or central, channel area of this aquifer is isolated from the overlying lacustrine sand aquifer by a continuous lacustrine silt and clay unit, which is the primary channel-fill deposit. The most productive areas of the Colonie Channel aquifer are typically the shallow peripheral areas, where conditions range from unconfined to confined. The most productive aquifer within the area is the alluvial aquifer, which is sustained to an unknown extent by induced infiltration of Mohawk River water. The chemical composition of ground water within the Clifton Park area varies widely in response to hydrogeologic setting, pumpage, and contamination from human activities. These chemical differences can be used to deduce ground-water flow paths within and between the unconfined and confined areas of the aquifer system. Six water types are defined; three are naturally occurring and three are the result of human activities. Precipitation that infiltrates the land surface is the sole source of recharge to the lacustrine sand aquifer; precipitation also recharges the alluvial aquifer and unconfined parts of the Colonie Channel aquifer. Ground-water withdrawals from confined or unconfined peripheral areas of the Colonie Channel aquifer induce flow from recharge areas, from the underlying bedrock, or from other confined aquifer areas. The rate of recharge to the confined central area of the Colonie Channel aquifer appears to be low. Potentiometric levels as much as 100 feet below water-table levels in the overlying lacustrine sand aquifer indicate two large depressions in the potentiometric surface; these depressions indicate that withdrawals from this aquifer have cumulatively exceeded the recharge rates. Localized recharge of the central channel area apparently occurs from two peripheral channel areas that are characterized by zones of elevated water levels and (or) by water chemistry that differs from those within the central channel area. Recharge from, or hydraulic connection with, adjoining segments of the Colonie Channel aquifer to the north and south is likely, but the potential for significant recharge is low because the aquifer is thin and poorly permeable.

New York↗

USGS2003

Ground-Water Resources in the Black Hills Area, South Dakota

The availability of ground-water resources in the Black Hills area is influenced by many factors including location, local recharge and ground-water flow conditions, and structural features. Thus, the availability of ground water can be extremely variable throughout the Black Hills area, and even when water is available, it may not be suitable for various uses depending on the water quality. The major bedrock aquifers in the Black Hills area are the Deadwood, Madison, Minnelusa, Minnekahta, and Inyan Kara aquifers. Minor bedrock aquifers occur in other hydrogeologic units, including confining units, due to fracturing and interbedded permeable layers. Various information and maps are presented in this report that describe availability and quality of ground-water resources in the Black Hills area. However, there is no guarantee of obtaining usable water at any location due to the extreme potential variability in conditions that can affect the availability and quality of ground water in the area. Maps presented in this report include the distribution of hydrogeologic units; depth to the top of the five formations that contain major aquifers; thickness of the five formations that contain major aquifers; potentiometric maps for the five major aquifers; saturated thickness of the Madison and Minnelusa aquifers; water temperature in the Madison aquifer; specific conductance in the Madison, Minnelusa, and Inyan Kara aquifers; hardness in the Inyan Kara aquifer; sulfate concentrations in the Minnelusa aquifer; and radon concentrations in the Deadwood aquifer. Water quality of the major aquifers generally is very good in and near outcrop areas but deteriorates progressively with distance from the outcrops. In the Minnelusa aquifer, an abrupt increase in concentrations of dissolved sulfate occurs downgradient from outcrop areas, where a zone of active anhydrite dissolution occurs. Most limitations for the use of ground water are related to aesthetic qualities associated with hardness and high concentrations of chloride, sulfate, sodium, manganese, and iron. Very few health-related limitations exist for ground water; most limitations are for radionuclides, such as radon and uranium. In addition, high concentrations of arsenic have been measured in a few samples from the Minnelusa aquifer.

Water-Resources Investigations Report↗

USGS2004

Water-resources-related information for the Milwaukee Metropolitan Sewerage District planning area, Wisconsin, 1970-2002

The Milwaukee Metropolitan Sewerage District (MMSD) Corridor Study is a three-phase project designed to improve the understanding of water resources in the stream corridors of the MMSD planning area by initially compiling existing data and using the compiled information to develop 3-year baseline and long-term monitoring plans. This report is one of the products of Phase I of the Corridor Study. A literature review of surface-water-quality, surface water- quantity, and ecology studies conducted from 1970 through 2001 was completed and is summarized in this report. An inventory of Geographic Information System spatial coverages available for the MMSD planning area has been assembled. A database of water, sediment, and tissue (fish, shellfish, and others) chemistry, macroinvertebrates, fish, algae, habitat, geomorphic, and other physical and ecological data was compiled from data sets from MMSD, U.S. Geological Survey, Wisconsin Department of Natural Resources, and the U.S. Environmental Protection Agency. More than 2.7 million results are available in the MMSD Corridor Study database and the compilation of multiple datasets allows for retrieving data from a central database rather than from each of the source datasets. Data for 1970 through 2002 were collected for the 420-square-mile planning area by various agencies using different field data-collection and laboratory analysis methods. Chemical constituents and ecological components that are important to an urban setting and well represented in the database were selected for further investigation. Each constituent or component is described in this report with some or all of the following: a text summary, map of sampling locations, and in some cases median concentrations, statistical distributions of concentrations by subwatershed, table of summary statistics by subwatershed, and graphs of temporal and (or) seasonal trends. Physical data presented in the report include streamflow, stream stage, and precipitation data. Chemical indicators of water quality presented in the report include field measurements and miscellaneous constituents (pH, alkalinity, specific conductance, hardness, dissolved oxygen, biochemical oxygen demand, and chloride), sediment (total suspended solids and suspended sediment), nutrients (total nitrogen, nitrate, Kjeldahl nitrogen, total phosphorus, and dissolved phosphorus), trace elements (cadmium, mercury, copper, lead, arsenic, chromium, nickel, and zinc), pesticides (historically used pesticides and pesticides still in use), and polychlorinated biphenyls. Ecological indicators of water quality discussed in the report include community surveys of macroinvertebrates and fish, chlorophyll a concentrations, habitat assessments and channel-measurement data, and fecal coliform and E. coli bacterial counts. In addition to the compilation of the database, a major purpose of this investigation was to identify additional sampling that should be conducted under the baseline monitoring phase, which will be the second phase of the Corridor Study. Additional sampling may include: • Some subwatersheds, such as those in the headwaters. • Emerging contaminants such as pharmaceuticals and personal care products (PPCPs), human hormones, organic wastewater contaminants, and other constituents that result from human activity. • E. coli, which can serve as an indicator of health risk to swimmers and other recreational water users. • Pesticides in all media. • PCBs. • Trace elements in water, bed sediment, and tissues (fish, shellfish, and others). • Samples during winter months or during early snowmelt episodes to address constituents such as chloride and some nutrients that have seasonal variability and that may be affected by factors such as road deicing during the winter. • Samples for macroinvertebrate and fish-community data and habitat assessments. • Physical data such as stream-channel cross-section profiles, bridge-scour assessments, flood-plain maps, structures, and shoreline conditions.

Wisconsin↗

USGS2004

Water-quality characteristics and trends for selected sites in or near the Earth Resources Observation Systems (EROS) Data Center, South Dakota, 1973-2000

This report presents data on water-quality samples that were collected in and near the Earth Resources Observation Systems (EROS) Data Center from 1973 through 2000. The investigation is a collaborated effort between the U.S. Geological Survey, Water Resources Discipline (WRD), and Geography (formerly National Mapping) Discipline, EROS Data Center. A water-quality monitoring program was initiated in 1973, when the EROS Data Center was constructed, and continues at the present time (2003). Under this program, water-quality samples were collected at various sites on the EROS Data Center's property and in the surrounding area. These sites include 4 wastewater-treatment lagoons, 1 site on EROS Lake located behind the EROS Data Center, 2 stream sites near the EROS Data Center, and 9 ground-water wells surrounding the EROS Data Center. Additionally, 3 sites on EROS Lake, 7 stream sites, and 9 ground-water sites are located within the study area and have been sampled during the period covered in the report. Some of these additional sites were part of the initial water-quality monitoring conducted during and immediately after the construction of the EROS Data Center. For other sites, some special sampling (depth-profile and bottom material) has occurred at times during the sampling history; however, these sites have little water-quality data and were not used for statistical or trend analysis. A trend-analysis program, Estimate TREND (ESTREND), was used to analyze for trends for one surface-water site, the Big Sioux River, which was the only site that had a substantial number of samples collected during an extensive period. The ESTREND trend-analysis program was used to analyze 16 constituents. Specific conductance and dissolved orthophosphate were the only constituents determined to have statistically significant trends. Results showed an increasing trend for specific conductance and a decreasing trend for dissolved orthophosphate. Scatter plots with regression smoothing lines for selected constituents are presented for selected surface-water and ground-water sites. Regression analyses using a Lowess (Locally Weighted Scatterplot Smoothing) smoothing line for Split Rock Creek, EROS Lake, the lagoon sites, and the ground-water sites indicated variable results, with some constituents indicating an increasing or decreasing trend, some having varied results, and others indicating no change during the sampling period.

South Dakota↗

USGS2003

Hydrologic Resources of Guam

Introduction The U.S. Territory of Guam, which lies in the western Pacific Ocean near latitude 13?28'N and longitude 144?45'E, is the largest (211 mi2) and southernmost of the islands in the Mariana chain. Ground water supplies about 80 percent of the drinking water for the island's 150,000 residents and nearly one million visitors per year. In northern Guam, water is obtained from wells that tap the upper part of a fresh ground-water lens in an aquifer composed mainly of limestone. About 180 wells, nearly all in the north, withdraw about 35 Mgal/d of water with chloride concentrations ranging from 6 to 585 mg/L. In southern Guam, the main source of freshwater is from surface water that runs off the weathered volcanic rocks that are exposed over much of the area. About 9.9 Mgal/d of freshwater is obtained using surface reservoirs. The island's freshwater resources are adequate to meet current (2003) needs, but future demands will eventually be higher. To better understand the hydrology of the island, the U.S. Geological Survey (USGS) entered into a cooperative study with the Water and Environmental Research Institute of the Western Pacific (WERI) at the University of Guam. The objective of the study was to provide a better understanding of the water resources of the island through analysis of data collected by the USGS on Guam. This report provides a description of the general hydrologic principles of the island's ground-water systems, as well as of the rainfall and geology of Guam. Hydrologic data described in the report include water levels, chloride concentrations, and pumpage from ground-water wells and streamflow data from southern Guam.

Water-Resources Investigations Report↗

USGS1979

Water resources of the Nisqually Lake area, Pierce County, Washington

This report presents data assembled during a July 1975 to August 1977 study of the water resources of an area within, and adjacent to, a part of the Fort Lewis Military Reservation that prior to 1917 was included in the Nisqually Indian Reservation. Because the area is within or near the artillery ranges of the U.S. Army, the existing water resources of the study area are almost undeveloped. The only surface-water bodies of significance in the study area are Muck Creek, Nisqually Lake, and springs. The flow of Muck Creek as measured at a gaging station at Roy, east of the study area, ranged from no flow to a maximum discharge of 692 cubic feet per second during the period 1956-77. No flow occurred there about 9 percent of the time during the period 19.56-71. A large spring discharged from 0.12 to 4.56 cubic feet per second during the study period. Development or diversion of Muck Creek near its mouth would provide sufficient water for a small- to medium-sized fish-rearing facility. The highest water temperature recorded at this site during the study was 14.0°C, in August 1977, with a stream discharge of 7.12 cubic feet per second. Nisqually Lake, with a surface area of about 89 acres, is shallow with a flat bottom. The existing lake water is relatively high with dissolved solids, organic nitrogen and phosphorus, and biologically productive. Species of warm-water fish are probably best suited for the lake. Ground water beneath the study area occurs in unconsolidated glacial drift or outwash of gravel, sand, silt, and clay. One of the permeable rock units is the Steilacoom Gravel of Pleistocene age. Yields to wells from this material in a nearby area are from 100 to 250 gallons per minute. Drilling of test wells in the study area would provide more reliable data on ground water.

Washington↗

USGS1979

Water resources of the Port Madison Indian Reservation, Washington

The study summarized in this report was made to provide Suquamish Tribal leaders with information on the reservation's surface- and ground-water resources. The Tribal leaders need this information to help them manage and protect their water resources against overdevelopment. The quantity of ground water that is estimated to be available for withdrawal on a long-term basis is about 600 million gallons per year in the western part of the reservation and 400 million gallons per year in the eastern part of the reservation. It should be possible, economically and practically, to capture at least 40 percent of this ground water with properly constructed and located wells before it is discharged into the sea. This is enough water to supply at least 5,000 and 3,500 people with domestic water in these respective areas—about four times the present population. Of nine stream sites that were studied on and near the reservation, the lowest average streamflows for a 7-day period estimated to occur an average of once in 2 years were 1.3 cubic feet per second or less. Streams at three of the sites have been observed dry at least once. The short period of data collection during this study limits the accuracy of statistical estimates of low flows. Both surface and ground water were found to be of good quality with no unusual or harmful constituents; there was no evidence of major pollution in 1977. In the future, seawater intrusion into the ground-water system and pollution of the surface water by improperly treated sewage waste water could become problems.

Washington↗

USGS1980

Water resources of the Port Gamble Indian Reservation, Washington

This report provides information on the water resources of the Port Gamble Indian Reservation, Washington, including ground- and surface-water quality and quantity data and interpretations of the data. This information was gathered to provide a base for management and protection of the water resources of the reservation. Ground water in the study area generally occurs in two aquifers. A shallow aquifer in weathered till (or fine sand and gravel) generally yields only enough water to wells to supply one or two households, and a lower artesian-aquifer system of sand and gravel layers near or below sea level produces higher yields--more than 65 gallons per minute to at least one well. Future supplies of ground water probably can be withdrawn from the lower artesian-aquifer system almost anywhere beneath the reservation. The estimated natural discharge of ground water from the lower artesian-aquifer system to Hood Canal and Port Gamble (bay) is about 42,000 cubic feet per day, or an average of about 220 gallons per minute. Of this amount, it is estimated that about 90 gallons per minute can be economically withdrawn, probably without greatly increasing chances of seawater intrusion. One well in the area taps a still deeper artesian aquifer that is otherwise unexplored. This aquifer, 75 to 80 feet or more below sea level, could possibly supply additional ground water for future use. Ground-water quality is good, but the water is moderately hard and has moderately high iron concentrations. Chloride analyses indicate that in 1977 there was no seawater intrusion into the lower aquifer tapped by wells in the community of Little Boston.

Washington↗

USGS1984

Water resources of the Palau Islands

The Palau Islands are a group of 350 islands, ranging in size from a few hundred square feet to the 153-square-mile island of Babelthuap. Babelthuap is the second largest island in the Western Pacific and comprises more than 80 percent of the total land area of the Palau Islands. Most of the islands are uninhabited limestone ridges covered with dense vegetation. These islands have no freshwater resources and are not included in this report. The island of Koror with an area of 3.6 square miles is the administrative, commercial, and population center of Palau and has an annual average rainfall of 148 inches. Short-term rainfall records at other locations in the islands indicate little variation in annual rainfall throughout the Palau Islands. Runoff-to-rainfall ratios for streams on Babelthuap show that about 70 percent of the rain falling on the island runs off to the ocean. The uniformity of rainfall and basin characteristics is shown by the excellent correlation between mean annual rainfall on Koror and streamflow on Babelthuap and by the close correlations between discharge at gaging stations and partial-record sites. Surface water quality is generally very good as shown by 55 chemical analyses of water from 18 sources. The dissolved solids concentration of water samples did not exceed 66 milligrams per liter. This report summarizes in one volume hydrologic data collection in a 14-year period of study and provides interpretations of the data than can be used by planners and public works officials as a basis for making decisions on the development and management of the islands' water resources.

Water-Resources Investigations Report↗

USGS1985

Water-resources appraisal of the Camp Swift lignite area, central Texas

The Camp Swift lignite area was studied to describe the hydrogeology and to provide baseline data of the ground-water and surface-water resources that could be affected by the strip mining of lignite. The investigation was centered on the 18-square mile Camp Swift Military Reservation where a reported 80 to 100 million short tons of commercially mineable lignite occurs within 200 feet of the land surface. Monthly ground-water levels from a network of 22 wells showed that water levels in wells in the Hooper, Simsboro, and Calvert Bluff Formations of the Wilcox Group had slight and generally insignificant waterlevel changes from May 1980 to May 1981. The water quality in the Calvert Bluff Formation, which contains the lignite, and in the Simsboro Formation, which is the major aquifer beneath the Calvert Bluff, generally is satisfactory for most uses. Hydraulic pressures in the Calvert Bluff are greater than in the Simsboro, and this pressure differential results in the potential for downward movement of water from the Calvert Bluff to the Simsboro. However, confining beds of lignite, clay, silt, and other fine-grained material at and near the base of the Calvert Bluff greatly retard this interformational movement of water but do not totally prevent downward leakage. Data were collected from four streamflow stations and five automated rain gages to appraise the quantity and quality of the surface-water resources. Big Sandy Creek, which crosses Camp Swift, generally has a base flow of less than 0.5 cubic feet per second and infrequently is dry. Dogwood Creek, which originates on Camp Swift, normally is dry. The flow of both streams changes rapidly in response to rainfall in the watersheds. The quality of the water in both streams generally is suitable for most uses, but varies significantly in response to variations in discharge and related factors. Alithologic examination of 255 feet of cored section that represents the overburden and the included lignite showed cyclic layering of fine sand, silt, clay, and lignite. Chemical analyses of the core were performed to determine the contents of major inorganic and trace constituents. These analyses indicate that the content of pyritic sulfur generally is small but variable.

Water-Resources Investigations Report↗

USGS1986

Water resources of the Lower Rio Grande de Arecibo alluvial valley, Puerto Rico

An assessment of the surface and groundwater resources of the lower Rio Grande de Arecibo alluvial valley was made between 1981 and 1983. Rio Grande de Arecibo is the major source of water in the valley with a mean-annual discharge of 527 cu ft/sec (382,000 acre-ft/yr). Its lowest mean-daily flow (low flow) during 12 yr of record is 50 cu ft/sec. Withdrawals of water from Rio Grande de Arecibo exceeding 15 cu ft/sec during periods of extreme low flows could cause reduction of recharge to the aquifer. However, withdrawals of as much as 35 cu ft/sec are possible when base flow ranges from 90 to 200 cu ft/sec without causing a reduction of aquifer recharge. An unconfined aquifer within the alluvial valley is hydraulically continuous with bordering limestone formations. A clay layer divides the alluvial aquifer into two separate hydraulic systems. Groundwater from the alluvial aquifer above the clay layer has not been widely developed. However, high yielding wells presently yield as much as 9.6 mil gal/day (10,800 acre-ft/yr) from the aquifers occurring below the clay layer within the alluvium and underlaying limestones. Transmissivity ranges from 3,000 sq ft/day in the alluvial area to 42,000 sq ft/day in the adjacent limestone areas. Total groundwater flow through aquifers within the study area (excluding water withdrawn by wells) is about 20.6 mil gal/day (23,100 acre-ft/yr). 50% of this amount is estimated to flow to the eastern area of Cano Tiburones and discharges as springs and seeps. An estimated 9.4 mil gal/day (10,500 acre-ft/yr) of additional groundwater can be withdrawn from the aquifers below the clay layer without reversing the northward hydraulic gradient. Seepage from Rio Grande de Arecibo to the groundwater system at the east side of the valley is probably the key to the development of groundwater resources in the Arecibo area. San Pedro spring, with an average discharge of 8.6 mil gal/day (9,600 acre-ft/yr), is undeveloped and represents a potential alternate source of water. (Author 's abstract)

Water-Resources Investigations Report↗