USGS Science⌕ Search

Geology topics

Research about Louisiana

Source-linked reports with geographic coverage including Louisiana.

At least 793 records · Page 44Linked to original sources
USGS1986

Louisiana hydrologic atlas map no. 2: Areal extent of freshwater in major aquifers of Louisiana

The areal availability of freshwater (cl content < 250 mg/L) in 14 major aquifers in Louisiana was investigated. The depth of occurrence of fresh groundwater in Louisiana is variable. The aquifers were mapped to show their areal extent from the outcrop or subcrop to the downdip limit of freshwater. Water in each aquifer becomes saline downdip; but in most areas an overlying (younger) aquifer contains freshwater. None of the major aquifer contains freshwater in northern Louisiana where the Vicksburg and Jackson groups crop out and the underlying Cockfield aquifer (Cockfield Formation) contains saline water.

Louisiana↗
USGS1985

Contaminant residues in fish and sediments from lakes in the Atchafalaya River Basin (Louisiana)

Conversion of bottomland hardwood forests ℴ agricultural land has reduced habitat and water quality in many lakes in the floodplain of the lower Mississippi River. The objectives of this study were to ascertain current contaminant residue concentrations in fish and sediment from lakes in the Atchafalaya River Basin and to determine the influence of overflow and agricultural land use on contaminant levels. Fish and sediment samples were collected from eight lakes that differed in overflow (no overflow, headwater overflow, backwater overflow) and land-use characteristics (presence or absence of agricultural land). Residue analysis of 24 sediment and 82 fish samples collected from the study lakes showed that contaminant residues were uniformly low. Total DDT concentrations, consisting mainly of DDE, were found in 98% of the fish samples and generally were the highest residues though they rarely exceeded 0.50 μg/g. Dieldrin, α-BHC and γ-BHC, in concentrations rarely exceeding 0.05 μg/g, were detected in about 50% of the fish samples. Total organochlorine pesticide and PCB residues were less than 2.00 μg/g in all fish from all lakes, except for a 3.46 μg/g total in spotted gar ( Lepisosteus oculatus ) from one lake. Sediments were free from pesticide residues except for occasional traces (0.01 μg/g) of α-BHC. Metal residue concentrations in fish and sediment samples were typical of uncontaminated areas. Lake systems in the Atchafalaya River Basin appeared to be relatively uncontaminated by agricultural pesticides, but metal and organic residues in fish were similar from lakes with the same land-use and overflow characteristics.

Louisiana↗
USGS1985

Generalized potentiometric surface of the Evangeline and equivalent aquifers in Louisiana, 1980

A generalized potentiometric-surface map defines the altitude of water levels for 1980 in wells in the Evangeline aquifer in southwestern Louisiana and stratigraphically equivalent aquifers in southeastern Louisiana. The Evangeline and equivalent aquifers increase in thickness from zero at the northern edge of the outcrop/subcrop belt to more than 2,000 feet along the southern limit of fresh water. The aquifers are recharged by rainfall on the overlying upland terrace deposits of south-central Louisiana, southeastern Louisiana, and southwestern Mississippi. The aquifers are under artesian conditions except locally in the recharge areas. The regional flow direction is primarily southward. Water levels in wells in the Evangeline aquifer are lowered by heavy pumping from the overlying Chicot aquifer in Evangeline and Acadia Parishes. Areally definable cones of depression result from pumpage from the Evangeline and equivalent aquifers in and near Baton Rouge, Eunice, and Ville Platte. Water levels may differ vertically within the aquifer near pumping centers. The map does not account for localized distortion of the regional flow pattern near these centers.

Louisiana↗
USGS1985

Analysis of the low-flow characteristics of streams in Louisiana

The U.S. Geological Survey, in cooperation with the Louisiana Department of Transportation and Development, Office of Public Works, used geologic maps, soils maps, precipitation data, and low-flow data to define four hydrographic regions in Louisiana having distinct low-flow characteristics. Equations were derived, using regression analyses, to estimate the 7Q 2 , 7Q 10 , and 7Q 20 flow rates for basically unaltered stream basins smaller than 525 square miles. Independent variables in the equations include drainage area (square miles), mean annual precipitation index (inches), and main channel slope (feet per mile). Average standard errors of regression ranged from +44 to +61 percent. Graphs are given for estimating the 7Q 2 , 7Q 10 , and 7Q 20 for stream basins for which the drainage area of the most downstream data-collection site is larger than 525 square miles. Detailed examples are given in this report for the use of the equations and graphs.

Louisiana↗
USGS1984

Presence and biomagnification of organochlorine chemical residues in oxbow lakes of northeastern Louisiana

Ninety-eight samples of 16 species of animals were collected at Lake Providence, 88 samples of 15 species at Lake Bruin, and 21 samples of 5 species at Lake St. John, Louisiana, between 15 July and 25 September 1980. Residues of 13 organochlorine compounds were identified in these samples. Substantial concentrations of many of these compounds throughout the food webs of all three lakes showed that the lakes act as sumps, accumulating residues from nearby agricultural land. DDT and its metabolites (DDE, TDE, and DDMU), toxaphene, and polychlorobiphenyls (PCBs) were the principal Organochlorine residues detected. With few exceptions, biomagnification of the principal residues was clearly illustrated. Tertiary consumers such as green-backed heron ( Butorides striatus ), snakes, spotted gar ( Lepisosteus oculatus ), and largemouth bass ( Micropterus salmoides ) contained the highest residues. Bluegill ( Lepomis macrochims ), blacktail shiner ( Notopis venustus ), yellow-crowned night-heron ( Nycticorax violaceus ), and other secondary consumers contained lower levels of residues. Primary consumers, crayfish ( Orconectes lancifer ) and threadfin shad ( Dorosoma petenense ), contained relatively low residue levels of most of the compounds. Frogs contained lower residue levels than expected based on their position in the food web. It is suggested that residue levels in immature green-backed herons and one or more of the longer-lived predators such as snakes, gars, or largemouth bass could be monitored to evaluate levels of Organochlorine chemical contaminants in aquatic habitats.

Louisiana↗
USGS1984

Water resources data, Louisiana, water year 1984

Water resources data for the 1984 water year for Louisiana consist of records of stage, discharge, and water quality of streams; stage, contents, and water quality of lakes and reservoirs; and water levels and water quality of ground water. This report, in one volume, contains records for water discharge at 72 gaging stations (including stage for 71 of these stations); stage only for 40 gaging stations and 11 lakes; water quality for 80 surface-water stations (including 26 gaging stations), 17 miscellaneous sites, 10 lakes, and 145 wells; and water levels for 423 observation wells. Also included are data for 141 crest-stage and flood-profile partial-record stations. Additional water data were collected at various sites not involved in the systematic data-collection program, and are published as miscellaneous measurements. These data represent that part of the National Water Data System operated by the U.S. Geological Survey and cooperating State and Federal agencies in Louisiana.

Louisiana↗
USGS1984

Regional geohydrology of the northern Louisiana salt-dome basin, part II, geohydrologic maps of the Tertiary aquifers and related confining layers

Regional geohydrologic maps show the altitude of the base and the thickness of the aquifers of Tertiary age and related confining layers in the northern Louisiana salt-dome basin. The limit of freshwater in aquifers is also shown. The basin has an area of about 3,000 square miles, and four geologic units of Tertiary age contain regional aquifers. From oldest (deepest) to youngest, the aquifers are in the Wilcox Group, Carrizo Sand, Sparta Sand, and Cockfield Formation. As the Wilcox is hydraulically interconnected with the overlying Carrizo, they are treated as one hydrologic unit, the Wilcox-Carrizo aquifer. The aquifers are separated by confining layers that retard water movement. In the northwestern part of the area, the Wilcox-Carrizo aquifer is separated from the underlying sand facies of the Nacatoch Sand (Cretaceous age) by a confining layer composed of the Midway Group (Tertiary age) and the underlying Arkadelphia Marl and an upper clay and marl facies of the Nacatoch Sand (both of Cretaceous age). In the remainder of the area, the Wilcox-Carrizo aquifer is separated from an underlying Cretaceous aquifer comprised of the Tokio Formation and Brownstown Marl by the Midway Group and several underlying Cretaceous units which in order of increasing age are the Arkadelphia Maril, Nacatoch Sand, Saratoga Chalk, Marlbrook Marl , and Annona Chalk. The Wilcox-Carrizo aquifer is separated from the Sparta aquifer by the overyling Cane River Formation. The Sparta aquifer is separated from the Cockfield aquifer by the overlying Cook Mountain Formation.

Louisiana↗
USGS1984

Preconstruction and simulated postconstruction ground-water levels at urban centers in the Red River Navigation Project area, Louisiana

The Red River Valley in Louisiana is 3 to 10 miles wide and is underlain by the Red River alluvial aquifer. This aquifer is in hydraulic connection with the Red River. Precipitation infiltrates the aquifer and water discharges from the aquifer at the Red River and major tributaries. Construction of locks and dams along the Red River will cause new, higher minimum stages for the river for each of the pools. Water levels will rise and outflow from the alluvial aquifer to the river after construction of the locks and dams will be at higher elevations because of the new river stages. Mathematical models of the stream-aquifer system simulate the effects of the lock and dam system for plan B-3, modified. Water-level changes in the aquifer in response to the changes imposed by the system are greatest near the river and are progressively smaller away from the river. The saturated zone in the fine-grained material overlying the aquifer provides the principal potential impact on structures and vegetation in urban areas. As water levels in the aquifer rise, the saturated zone above the aquifer will decrease the thickness. The soil zone in low areas in some communities will be waterlogged. (USGS)

Louisiana↗
USGS1983

Water resources data, Louisiana, water year 1983, volume 1. Central and northern Louisiana

Water resources data for the 1983 water year for Louisiana consist of records of stage, discharge, and water quality of streams; stage, contents, and water quality of lakes and reservoirs; and water levels and water quality of ground water. This report, in two volumes, contains records for water discharge at 79 gaging stations (including stage for 69 of these stations); stage only for 50 gaging stations and 11 lakes; contents for 1 reservoir; water quality for 110 surface-water stations (including 33 gaging stations), 10 miscellaneous sites, 12 lakes, and 213 wells; and water levels for 679 observation wells. Also included are data for 195 crest-stage and flood profile partial-record stations. Additional water data were collected at various sites not involved in the systematic data-collection program, and are published as miscellaneous measurements. These data represent that part of the National Water Data System operated by the U.S. Geological Survey and cooperating State and Federal agencies in Louisiana.

Louisiana↗
USGS1983

Water resources data, Louisiana, water year 1983, volume 2. Southern Louisiana

Water resources data for the 1983 water year for Louisiana consist of records of stage, discharge, and water quality of streams; stage, contents, and water quality of lakes and reservoirs; and water levels and water quality of ground water. This report, in two volumes, contains records for water discharge at 79 gaging stations (including stage for 69 of these stations); stage only for 50 gaging stations and 11 lakes; contents for 1 reservoir; water quality for 110 surface-water stations (including 33 gaging stations), 10 miscellaneous sites, and 12 lakes, and 213 wells; and water levels for 679 observation wells. Also included are data for 195 crest-stage and flood-profile partial-record stations. Additional water data were collected at various sites not involved in the systematic data-collection program, and are published as miscellaneous measurements. These data represent that part of the National Water Data System operated by the U.S. Geological Survey and cooperating State and Federal agencies in Louisiana.

Louisiana↗
USGS1983

Regional geohydrology of the northern Louisiana salt-dome basin, part IV, hydraulic characteristics of the Wilcox-Carrizo aquifer

The Wilcox Group of Paleocene-Eocence age and the Carrizo Sand of Eocene age compose the Wilcox-Carrizo aquifer. Results of 25 aquifer tests and permeability determinations from 43 sidewall cores show that the hydraulic characteristics of the aquifer are variable. Studies of the Carrizo showed that hydraulic conductivity increased as sand-bed thickness increased. Hydraulic conductivity averaged 29 feet per day for sand beds 25 to 100 feet in thickness and 40 feet per day for sand beds 100 to 200 feet in thickness. Based on the aquifer tests and sidewall core analyses, hydraulic conductivity does not increase with increased thickness for the Wilcox part of the aquifer. Permeabilities determined from sidewall cores ranged from less than 1 to more than 3,000 millidarcies (less than 0.002 to more than 7.3 feet per day). Values of hydraulic conductivity determined from aquifer tests ranged from less than 1 to 35 feet per day. (USGS)

Louisiana↗
USGS1982

Water resources data, Louisiana, water year 1982: Volume 1. Central and northern Louisiana

Water resources data for the 1982 water year for Louisiana consist of records of stage, discharge, and water quality of streams; stage, contents, and water quality of lakes and reservoirs; and water levels and water quality of ground water. This report, in two volumes, contains records for water discharge at 77 gaging stations (including stage for 65 of these stations); stage only for 64 gaging stations and 9 lakes; contents for 1 reservoir; water quality for 104 surface-water stations (including 31gaging stations) 20 miscellaneous sites, and 8 lakes, and 223 wells; and water levels for 526 observation wells. Also included are data for 209 cres-stage and flood-profile partial-record stations. Additional water data were collected at various sites not involved in the systematic data-collection program, and are published as miscellaneous measurements. Records for a few pertinent stations in bordering states are also included in this report. These data represent that part of the National Water Data System operated by the U.S. Geological Survey and cooperating State and Federal agencies in Louisiana.

Louisiana↗