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Roland W. Tollett

Publications and source records attributed to Roland W. Tollett.

At least 19 recordsLinked to original sources
USGS2026

Altitude of the potentiometric surface and depth to water in the Mississippi River Valley alluvial aquifer, spring 2024

Potentiometric-surface and depth-to-water maps for spring 2024 were created for the Mississippi River Valley alluvial aquifer using groundwater-altitude data from 1,151 wells completed in the Mississippi River Valley alluvial aquifer and from the altitude of the top of the water surface in area rivers from 160 U.S. Geological Survey and U.S. Army Corps of Engineers streamgages. The potentiometric-surface and depth-to-water maps for 2024 were created to support investigations to characterize the Mississippi River Valley alluvial aquifer as part of the U.S. Geological Survey Water Availability and Use Science Program. Sufficient data were available to map the potentiometric surface and depth to water of the Mississippi River Valley alluvial aquifer for spring 2024 for about 83 percent of the aquifer area. The potentiometric contours ranged from 0 to 330 feet (ft) above the North American Vertical Datum of 1988. The regional direction of the groundwater gradient was generally to the south-southwest, except in areas of groundwater-altitude depressions, where the groundwater gradient direction was into the depression, and near rivers, where the groundwater gradient direction was either from the aquifer to the river or from the river into the aquifer. Groundwater depressions in the potentiometric-surface map are in the lower one-half of the Cache region and in most of the Grand Prairie and Delta regions. Depth to water by well in the Mississippi River Valley alluvial aquifer in spring 2024 ranged from 0.27 ft above land surface to 145.65 ft below land surface.

Arkansas, Illinois, Kentucky, Louisiana, Mississip↗
USGS2025

Altitude of the potentiometric surface and depth to water in the Mississippi River Valley alluvial aquifer, spring 2022

Potentiometric-surface and depth-to-water maps for spring 2022 were created for the Mississippi River Valley alluvial aquifer (MRVA) using groundwater-altitude data from 1,136 wells completed in the MRVA and from the altitude of the top of the water surface in area rivers from 160 streamgages. The potentiometric-surface and depth-to-water maps for 2022 were created to support investigations to characterize the MRVA as part of the U.S. Geological Survey Water Availability and Use Science Program. Sufficient data were available to map the potentiometric surface and depth to water of the MRVA for spring 2022 for about 83 percent of the aquifer area. The potentiometric contours ranged from 0 to 340 feet (ft) above the North American Vertical Datum of 1988. The regional direction of groundwater gradient was generally to the south-southwest, except in areas of groundwater-altitude depressions, where the groundwater gradient was into the depression, and near rivers, where the groundwater gradient can be from aquifer to the river or from the river into the aquifer. There are large depressions in the potentiometric-surface map in the lower one-half of the Cache region and in much of the Grand Prairie and Delta regions. Depth to water in the MRVA, spring 2022, by well ranged from 5.00 ft above land surface to 145.66 ft below land surface.

Mississippi River Valley alluvial aquifer↗
USGS2022

Aquatic-life criteria compared to concentrations of cadmium, copper, lead, and zinc in streams near Fort Polk Military Reservation, Louisiana, December 2015–August 2016

The primary focus of this study was to document cadmium, copper, lead, and zinc concentrations in selected streams near the U.S. Army Joint Readiness Training Center (JRTC) and Fort Polk Military Reservation and to compare those values to Federal and State aquatic-life criteria guidelines. The acute aquatic-life criteria used for this study are as follows: the U.S. Environmental Protection Agency (EPA) aquatic-life criterion maximum concentration (CMC) based on hardness, the EPA CMC for copper based on the biotic ligand model (BLM), and the Louisiana Department of Environmental Quality (LDEQ) acute aquatic-life criteria based on hardness. The chronic aquatic-life criteria used for this study are as follows: the EPA aquatic-life criterion continuous concentration (CCC) based on hardness, the EPA CCC for copper based on the BLM, and the LDEQ chronic aquatic-life criteria based on hardness. Cadmium was detected in one stream-water sample collected near the Peason Ridge training area, hereinafter referred to as Peason Ridge, and one stream-water sample collected near North and South Fort Polk, hereinafter referred to as the Main Post. A cadmium concentration of an estimated (E) 0.48 microgram per liter (μg/L) in a stream-water sample collected during high stage near Peason Ridge exceeded the EPA CMC of 0.10 μg/L. A second cadmium concentration of E0.33 μg/L in a stream-water sample collected during low stage exceeded the EPA CMC of 0.22 μg/L, and a 4-day average cadmium concentration of E0.16 μg/L exceeded the EPA CCC of 0.14 μg/L. Copper was detected in 34 stream-water samples collected near Peason Ridge and 22 stream-water samples collected near the Main Post. The EPA acute criteria for copper were exceeded 17 times in stream-water samples collected near Peason Ridge and 19 times in stream-water samples collected near the Main Post. The EPA chronic criteria for copper were exceeded five times in stream-water samples collected near Peason Ridge and seven times in stream-water samples collected near the Main Post. Lead was detected in 31 stream-water samples collected near Peason Ridge and 16 stream-water samples collected near the Main Post. A concentration of 6.0 μg/L in a stream-water sample collected during high stage at site 2 near Peason Ridge exceeded the EPA CMC of 5.5 μg/L, and a concentration of 4.1 μg/L in a stream-water sample collected during high stage at site 4 near the Main Post exceeded the EPA CMC of 2.9 μg/L. The EPA chronic criteria for lead were exceeded nine times in stream-water samples collected near Peason Ridge and three times in stream-water samples collected near the Main Post. The LDEQ chronic criteria were exceeded two times in stream-water samples near Peason Ridge and none near the Main Post. Zinc was detected in 35 stream-water samples collected near Peason Ridge and 17 stream-water samples collected near the Main Post. A concentration of 100 μg/L in a stream-water sample collected at site 3 near Peason Ridge exceeded the EPA CMC of 8.9 μg/L and the LDEQ acute aquatic-life criteria of 36 μg/L. One 4-day average zinc concentration, E28 μg/L for stream-water samples collected from site 3 near Peason Ridge, exceeded the EPA CCC of 8.2 μg/L; however, no concentrations of zinc exceeded the LDEQ chronic aquatic-life criteria near Peason Ridge or the Main Post. The presence of copper, lead, and zinc at concentrations above the calculated acute or chronic aquatic-life criteria for some stream-water samples collected in relatively pristine streams near Peason Ridge and the Main Post indicates that these waters are susceptible to elevated trace element concentrations likely because of low ionic strength and hardness.

Louisiana↗
USGS2021

Altitude of the potentiometric surface in the Mississippi River Valley alluvial aquifer, spring 2020

The purpose of this report is to present a potentiometric-surface map for the Mississippi River Valley alluvial aquifer (MRVA). The source data for the map were groundwater-altitude data from wells measured manually or continuously generally in spring 2020 and from the altitude of the top of the water surface measured generally on April 9, 2020, in rivers in the area.

Arkansas, Illinois, Kentucky, Louisiana, Mississip↗
USGS2020

Altitude of the potentiometric surface in the Mississippi River Valley alluvial aquifer, spring 2018

A potentiometric-surface map for spring 2018 was created for the Mississippi River Valley alluvial (MRVA) aquifer using available groundwater-altitude data from 1,126 wells completed in the MRVA aquifer and from the altitude of the top of the water surface in area rivers from 66 streamgages. Personnel from Arkansas Natural Resources Commission, Arkansas Department of Health, Arkansas Geological Survey, Illinois Department of Agriculture, Illinois State Water Survey, Louisiana Department of Natural Resources, Louisiana Department of Transportation and Development, Mississippi Department of Environmental Quality, Missouri Department of Natural Resources, Yazoo Mississippi Delta Joint Water Management District, U.S. Department of Agriculture-Natural Resources Conservation Service, and U.S. Geological Survey (USGS) routinely collect groundwater-level data from wells screened in the MRVA aquifer. The USGS and the U.S. Army Corps of Engineers routinely collect data on river stage and streamflow for the rivers overlying the MRVA aquifer area. The potentiometric-surface map for 2018 was created utilizing existing groundwater and surface-water altitudes to support investigations to characterize the MRVA aquifer as part of the USGS Water Availability and Use Science Program. Sufficient data were available to map the potentiometric surface of the MRVA aquifer for spring 2018 for about 87 percent of the aquifer area. The potentiometric contours ranged from 10 to 340 feet above North American Vertical Datum of 1988. The regional direction of groundwater flow was generally to the south-southwest, except in areas of groundwater-altitude depressions, where groundwater flowed into the depression, and near rivers, where flow can be from aquifer to the river or from the river into the aquifer. There are large depressions in the potentiometric-surface map in the lower one-half of the Cache region and in most of the Grand Prairie and Delta regions.

Mississippi River Valley alluvial aquifer↗
USGS2017

Methane and benzene in drinking-water wells overlying the Eagle Ford, Fayetteville, and Haynesville Shale hydrocarbon production areas

Water wells ( n = 116) overlying the Eagle Ford, Fayetteville, and Haynesville Shale hydrocarbon production areas were sampled for chemical, isotopic, and groundwater-age tracers to investigate the occurrence and sources of selected hydrocarbons in groundwater. Methane isotopes and hydrocarbon gas compositions indicate most of the methane in the wells was biogenic and produced by the CO 2 reduction pathway, not from thermogenic shale gas. Two samples contained methane from the fermentation pathway that could be associated with hydrocarbon degradation based on their co-occurrence with hydrocarbons such as ethylbenzene and butane. Benzene was detected at low concentrations (<0.15 μg/L), but relatively high frequencies (2.4–13.3% of samples), in the study areas. Eight of nine samples containing benzene had groundwater ages >2500 years, indicating the benzene was from subsurface sources such as natural hydrocarbon migration or leaking hydrocarbon wells. One sample contained benzene that could be from a surface release associated with hydrocarbon production activities based on its age (10 ± 2.4 years) and proximity to hydrocarbon wells. Groundwater travel times inferred from the age-data indicate decades or longer may be needed to fully assess the effects of potential subsurface and surface releases of hydrocarbons on the wells.

Environmental Science & Technology↗
USGS2015

The quality of our Nation's waters: Water quality in the Mississippi embayment-Texas coastal uplands aquifer system and Mississippi River Valley alluvial aquifer, south-central United States, 1994-2008

About 8 million people rely on groundwater from the Mississippi embayment&mdash;Texas coastal uplands aquifer system for drinking water. The Mississippi River Valley alluvial aquifer also provides drinking water for domestic use in rural areas but is of primary importance to the region as a source of water for irrigation. Irrigation withdrawals from this aquifer are among the largest in the Nation and play a key role in the economy of the area, where annual crop sales total more than $7 billion. The reliance of the region on both aquifers for drinking water and irrigation highlights the importance of long-term management to sustain the availability and quality of these resources.

Alabama, Arkansas, Kentucky, Louisiana, Mississipp↗
USGS2011

Processes affecting geochemistry and contaminant movement in the middle Claiborne aquifer of the Mississippi embayment aquifer system

Groundwater chemistry and tracer-based age data were used to assess contaminant movement and geochemical processes in the middle Claiborne aquifer (MCA) of the Mississippi embayment aquifer system. Water samples were collected from 30 drinking-water wells (mostly domestic and public supply) and analyzed for nutrients, major ions, pesticides, volatile organic compounds (VOCs), and transient age tracers (chlorofluorocarbons, tritium and helium-3, and sulfur hexafluoride). Redox conditions are highly variable throughout the MCA. However, mostly oxic groundwater with low dissolved solids is more vulnerable to nitrate contamination in the outcrop areas east of the Mississippi River in Mississippi and west Tennessee than in mostly anoxic groundwater in downgradient areas in western parts of the study area. Groundwater in the outcrop area was relatively young (apparent age of less than 40 years) with significantly ( p < 0.05) higher dissolved oxygen and nitrate&ndash;N concentrations and higher detections of pesticides and VOCs compared to water samples from wells in downgradient areas. Oxygen reduction and denitrification rates were low compared to other aquifers in the United States (zero order rate constants for oxygen reduction and denitrification were 4.7 and 5&ndash;10 &mu;mol/L/year, respectively). Elevated concentrations of nitrate&ndash;N, and detections of pesticides and VOCs in some deep public supply wells (>50 m depth) indicated contaminant movement from shallow parts of the aquifer into deeper oxic zones. Given the persistence of nitrate in young oxic groundwater that was recharged several decades ago, and the lack of a confining unit, the downward movement of young contaminated water may result in higher nitrate concentrations over time in deeper parts of the aquifer containing older oxic water.

Claiborne Aquifer;Mississippi Embayment↗
USGS2009

Quality of Shallow Groundwater and Drinking Water in the Mississippi Embayment-Texas Coastal Uplands Aquifer System and the Mississippi River Valley Alluvial Aquifer, South-Central United States, 1994-2004

The Mississippi embayment-Texas coastal uplands aquifer system is an important source of drinking water, providing about 724 million gallons per day to about 8.9 million people in Texas, Louisiana, Mississippi, Arkansas, Missouri, Tennessee, Kentucky, Illinois, and Alabama. The Mississippi River Valley alluvial aquifer ranks third in the Nation for total withdrawals of which more than 98 percent is used for irrigation. From 1994 through 2004, water-quality samples were collected from 169 domestic, monitoring, irrigation, and public-supply wells in the Mississippi embayment-Texas coastal uplands aquifer system and the Mississippi River Valley alluvial aquifer in various land-use settings and of varying well capacities as part of the U.S. Geological Survey's National Water-Quality Assessment Program. Groundwater samples were analyzed for physical properties and about 200 water-quality constituents, including total dissolved solids, major inorganic ions, trace elements, radon, nutrients, dissolved organic carbon, pesticides, pesticide degradates, and volatile organic compounds. The occurrence of nutrients and pesticides differed among four groups of the 114 shallow wells (less than or equal to 200 feet deep) in the study area. Tritium concentrations in samples from the Holocene alluvium, Pleistocene valley trains, and shallow Tertiary wells indicated a smaller component of recent groundwater than samples from the Pleistocene terrace deposits. Although the amount of agricultural land overlying the Mississippi River Valley alluvial aquifer was considerably greater than areas overlying parts of the shallow Tertiary and Pleistocene terrace deposits wells, nitrate was rarely detected and the number of pesticides detected was lower than other shallow wells. Nearly all samples from the Holocene alluvium and Pleistocene valley trains were anoxic, and the reducing conditions in these aquifers likely result in denitrification of nitrate. In contrast, most samples from the Pleistocene terrace deposits in Memphis, Tennessee, were oxic, and the maximum nitrate concentration measured was 6.2 milligrams per liter. Additionally, soils overlying the Holocene alluvium and Pleistocene valley trains, generally in areas near the wells, had lower infiltration rates and higher percentages of clay than soils overlying the shallow Tertiary and Pleistocene terrace deposits wells. Differences in these soil properties were associated with differences in the occurrence of pesticides. Pesticides were most commonly detected in samples from wells in the Pleistocene terrace deposits, which generally had the highest infiltration rates and lowest clay content. Median dissolved phosphorus concentrations were 0.07, 0.11, and 0.65 milligram per liter in samples from the shallow Tertiary, Pleistocene valley trains, and Holocene alluvium, respectively. The widespread occurrence of dissolved phosphorus at concentrations greater than 0.02 milligram per liter suggests either a natural source in the soils or aquifer sediments, or nonpoint sources such as fertilizer and animal waste or a combination of natural and human sources. Although phosphorus concentrations in samples from the Holocene alluvium were weakly correlated to concentrations of several inorganic constituents, elevated concentrations of phosphorus could not be attributed to a specific source. Phosphorus concentrations generally were highest where samples indicated anoxic and reducing conditions in the aquifers. Elevated dissolved phosphorus concentrations in base-flow samples from two streams in the study area suggest that transport of phosphorus with groundwater is a potential source contributing to high yields of phosphorus in the lower Mississippi River basin. Water from 55 deep wells (greater than 200 feet deep) completed in regional aquifers of Tertiary age represent a sample of the principal aquifers used for drinking-water supply in the study area. The wells were screened in both confined and

Scientific Investigations Report↗
USGS2008

Monitoring Inland Storm Surge and Flooding From Hurricane Gustav in Louisiana, September 2008

On August 29-31, 2008, the U.S. Geological Survey (USGS) deployed a mobile monitoring network consisting of 124 pressure transducers (sensors) (figs. 1, 2) at 80 sites over an area of about 4,200 square miles to record the timing, extent, and magnitude of inland hurricane storm surge and coastal flooding generated by Hurricane Gustav, which made landfall in southeastern Louisiana on September 1. One-hundred twenty-one sensors from 61 sites (fig. 3) were recovered. Thirty-seven sites from which sensors were recovered were in the New Orleans area, and the remaining 24 sites were distributed throughout southeastern Louisiana. Sites were categorized as surge (21), riverine flooding (18), anthropogenic (affected by the operation of gates or pumps) (17), or mixed/uncertain on the basis of field observations and the appearance of the water-level data (5).

Open-File Report↗
USGS2008

Physicochemical properties and chemical characteristics of water, bed sediment, and mussel tissue from selected streams near the Redleg and Peason Ridge impact areas, Fort Polk Military Reservation, Louisiana, June 2001 - November 2003

At the request of the U.S. Army Joint Readiness Training Center and Fort Polk, the U.S. Geological Survey collected and analyzed water, bed-sediment, and mussel-tissue samples from selected streams near the Redleg impact area (RIA) and Peason Ridge impact areas (PRIA) at the Fort Polk Military Reservation (Reservation), Louisiana. from June 2001 through November 2003. Samples were collected from 13 sites, including 2 reference sites. Water was analyzed for physicochemical properties; water and bed sediment were analyzed for major inorganic ions, cyanide, perchlorate, trace elements, total organic carbon, nutrients, and explosive compounds; and mussel tissue from three sites was analyzed for explosive compounds only. The two reference sites, one near the RIA and one near the PRIA, were selected to provide baseline data for these areas. Streams near the RIA were acidic and low in buffering capacity. with pH measurements ranging from 5.0 to 6.6. Cation concentrations were less than or equal to E3.3J mg/L (E, estimated; J, method blank contamination; milligrams per liter), and anion concentrations were less than or equal to E7.3 mg/L. Field measurements and major inorganic ions concentrations were similar to the RIA reference site and to previously sampled nearby streams, indicating streams near the RIA were typical of streams near the eastern part of the Main Post. Streams near the PRIA were slightly acidic to neutral and low in buffering capacity, with pH measurements ranging from 5.7 to 6.9. Cation concentrations were less than or equal to 6.2 mg/L, and anion concentrations were less than or equal to 16 mg/L. Streams near the PRIA were higher than the RIA for most physicochemical properties and constituents, hut typical of streams near the headwaters of the Calcasieu River. All concentrations of sulfate, chloride, and fluoride were less than the U.S. Environmental Protection Agency (USEPA) Secondary Drinking-Water Regulations (SDWR) of 250, 250, and 2.0 mg/L, respectively. Concentrations of cations calcium, magnesium. and potassium for sites near both the RIA and PRIA were higher in depositional bed-sediment samples than in bulk samples. Higher cation concentrations were likely due to higher clay and organic content in the depositional samples. The trace elements detected in the highest concentrations in water and bed sediment were aluminum, iron, and manganese. All aluminum concentrations in water were within the range or greater than the USEPA SDWR range from 50 to 200 ug/L (micrograms per liter). All but four iron concentrations in water exceeded the SDWR. Manganese concentrations in seven water samples at the RIA sites and four samples at the PRIA sites were greater than the SDWR. These concentrations of cations were consistent with soil characteristics and low pH measurements of stream water and rainfall in the area. All other trace-element concentrations in water were less than regulatory guidelines and regulations except the USEPA Maximum Contaminant Level Goal of 0 ug/L for arsenic and lead and 0.5 u/L for thallium. Arsenic, lead, and thallium concentrations were similar to those detected in blank samples or those reported for the reference sites. The Canadian Council of Ministers of the Environment (CCME) has established bed-sediment guidelines for seven trace elements: arsenic, cadmium, chromium, copper, lead, mercury, and zinc. No concentrations exceeded the CCME Probable Effect Level, and only one arsenic concentration of 8.87 mg/kg (milligrams per kilogram), in a depositional sample from one of the RIA sites, exceeded the CCME Interim Sediment Quality Guideline of 5.9 mg/kg. The median concentrations of total organic carbon in water were 5.3 mg/L at the RIA and 4.0 mg/L at the PRIA, and both concentrations were less than the average dissolved organic carbon concentration of 5.75 mg/L for all world rivers. All detected nutrient concentrations in water were less than USEPA guidelines and regulations. The largest nutrient concentrations in water and bed-sediment samples were total organic nitrogen, measured as total Kjeldahl nitrogen; they included a maximum concentration of 0.53 mg/L in water at the RIA sites, E0.38 mg/L in water at the PRIA sites, 294 mg/kg in hulk bed sediment. and 1,740 mg/kg in depositional bed sediment. Four explosive compounds, 1,3,5-trinitrobenzene, 2,4,6-trinitrotoluene, RDX (hexahydro-1,3,5-trinitro-1,3,5- triazine), and tetryl, were detected in water near the RIA; one compound, HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7- tetrazocine), was detected in bed sediment near the PRIA; and one compound, nitroglycerin, was detected in mussel tissue near the RIA. The most frequently detected explosive compound, RDX, was detected in 10 water samples from 5 sites near the RIA. Concentrations of explosive compounds in water were less than USEPA Health Advisories available for reference.

Louisiana↗
USGS2007

Monitoring Hurricane Rita Inland Storm Surge

Pressure transducers (sensors) are accurate, reliable, and cost-effective tools to measure and record the magnitude, extent, and timing of hurricane storm surge. Sensors record storm-surge peaks more accurately and reliably than do high-water marks. Data collected by sensors may be used in storm-surge models to estimate when, where, and to what degree stormsurge flooding will occur during future storm-surge events and to calibrate and verify stormsurge models, resulting in a better understanding of the dynamics of storm surge.

Louisiana↗
USGS2007

Effects of Hardened Low-Water Crossings on Periphyton and Water Quality in Selected Streams at the Fort Polk Military Reservation, Louisiana, 1998-99 and 2003-04

In 2003, the U.S. Geological Survey (USGS), at the request of the U.S. Army Joint Readiness Training Center and Fort Polk, began a follow-up study to determine whether installation and modification of hardened low-water crossings had short-term (less than 1 year) or long-term (greater than 1 year) effects on periphyton or water quality in five streams at the Fort Polk Military Reservation, Louisiana. Periphyton data were statistically analyzed for possible differences between samples collected at upstream and downstream sites and before and after low-water crossings were modified on three streams, Big Brushy Creek, Tributary to East Fork of Sixmile Creek, and Tributary to Birds Creek, during 2003?04. Periphyton data also were analyzed for possible differences between samples collected at upstream and downstream sites on two streams, Tributary to Big Brushy Creek and Little Brushy Creek, during 1998?99 and 2003. Variations in periphyton communities could not be conclusively attributed to the modifications. Most of the significant changes in percent frequency of occurrence and average cell density of the 10 most frequently occurring periphyton taxa were increases at downstream sites after the hardened low-water crossing installations or modifications. However, these changes in the periphyton community are not necessarily deleterious to the community structure. Water-quality data collected from upstream and downstream sites on the five streams during 2003?04 were analyzed for possible differences caused by the hardened crossings. Generally, average water-quality values and concentrations were similar at upstream and downstream sites. When average water-quality values or concentrations changed significantly, they almost always changed significantly at both the upstream and downstream sites. It is probable that observed variations in water quality at both upstream and downstream sites are related to differences in rainfall and streamflow during the sample collection periods rather than an effect of the hardened low-water crossing installations or modifications, but additional study is needed.

Scientific Investigations Report↗
USGS2006

Hurricane Rita surge data, southwestern Louisiana and southeastern Texas, September to November 2005

Pressure transducers and high-water marks were used to document the inland water levels related to storm surge generated by Hurricane Rita in southwestern Louisiana and southeastern Texas. On September 22-23, 2005, an experimental monitoring network consisting of 47 pressure transducers (sensors) was deployed at 33 sites over an area of about 4,000 square miles to record the timing, extent, and magnitude of inland hurricane storm surge and coastal flooding. Sensors were programmed to record date and time, temperature, and barometric or water pressure. Water pressure was corrected for changes in barometric pressure and salinity. Elevation surveys using global-positioning systems and differential levels were used to relate all storm-surge water-level data, reference marks, benchmarks, sensor measuring points, and high-water marks to the North American Vertical Datum of 1988 (NAVD 88). The resulting data indicated that storm-surge water levels over 14 feet above NAVD 88 occurred at three locations and rates of water-level rise greater than 5 feet per hour occurred at three locations near the Louisiana coast. Quality-assurance measures were used to assess the variability and accuracy of the water-level data recorded by the sensors. Water-level data from sensors were similar to data from co-located sensors, permanent U.S. Geological Survey streamgages, and water-surface elevations performed by field staff. Water-level data from sensors at selected locations were compared to corresponding high-water mark elevations. In general, the water-level data from sensors were similar to elevations of high quality high-water marks, while reporting consistently higher than elevations of lesser quality high-water marks.

Data Series↗
USGS2006

Monitoring Inland Storm Surge and Flooding from Hurricane Rita

Pressure transducers (sensors) and high-water marks were used to document the inland water levels related to storm surge generated by Hurricane Rita in southwestern Louisiana and southeastern Texas. On September 22-23, 2005, an experimental monitoring network of sensors was deployed at 33 sites over an area of about 4,000 square miles to record the timing, extent, and magnitude of inland hurricane storm surge and coastal flooding. Sensors were programmed to record date and time, temperature, and barometric or water pressure. Water pressure was corrected for changes in barometric pressure and salinity. Elevation surveys using global-positioning systems and differential levels were used to relate all storm-surge water-level data, reference marks, benchmarks, sensor measuring points, and high-water marks to the North American Vertical Datum of 1988 (NAVD 88). The resulting data indicated that storm-surge water levels over 14 feet above NAVD 88 occurred at three locations, and rates of water-level rise greater than 5 feet per hour occurred at three locations near the Louisiana coast.

Fact Sheet↗
USGS2004

Water quality in the Acadian-Pontchartrain drainages: Louisiana and Mississippi, 1999–2001

This report contains the major findings of a 1999-2001 assessment of water quality in the Acadian-Pontchartrain Drainages Study Unit. It is one of a series of reports by the National Water-Quality Assessment (NAWQA) Program that present major findings in 51 major river basins and aquifer systems across the Nation. In these reports, water quality is discussed in terms of local, State, and regional issues. Conditions in a particular basin or aquifer system are compared to conditions found elsewhere and to selected national benchmarks, such as those for drinking-water quality and the protection of aquatic organisms. This report is intended for individuals working with water-resource issues in Federal, State, or local agencies, universities, public interest groups, or in the private sector. The information will be useful in addressing a number of current issues, such as the effects of agricultural and urban land use on water quality, human health, drinking water, source-water protection, hypoxia and excessive growth of algae and plants, pesticide registration, and monitoring and sampling strategies. This report also is for individuals who wish to know more about the quality of streams and ground water in areas near where they live, and how that water quality compares to other areas across the Nation. The water-quality conditions in the Acadian-Pontchartrain Drainages Study Unit summarized in this report are discussed in detail in other reports that can be accessed from (http://la.water.usgs.gov/nawqa/default.htm). Detailed technical information, data and analyses, collection and analytical methodology, models, graphs, and maps that support the findings presented in this report in addition to other reports in this series from other basins can be accessed from the national NAWQA Web site (http://water.usgs.gov/nawqa).

Louisiana, Mississippi↗
USGS2004

Quality of water from shallow wells in the rice-growing area in southwestern Louisiana, 1999 through 2001

In 1999-2001, the U.S. Geological Survey installed and sampled 27 shallow wells in the rice-growing area in southwestern Louisiana as part of the Acadian-Pontchartrain Study Unit of the National Water-Quality Assessment Program. The purpose of this report is to describe the waulity of water from shallow wells in the rice-growing area and to relate that water quality to natural and anthropogenic activities, particularly rice agriculture. Ground-water samples were analyzed for general ground-water properties and about 150 water-quality constituents, including major inorganic ions, trace elements, nutrients, dissolved organic carbon (DOC), pesticides, radon, chloroflourocarbons, and selected stable isotopes. Dissolved solids concentrations for 17 wells exceeded the U.S. Environmental Protection Agency secondary minimum containment level of 500 milligrams per liter (mg/L) for drinking water. Concentrations for major pesticides generally were less than the maximum contaminant levels for drinking water. Two major inorganic ions, sulfate and chloride, and two trace elements, iron and manganese, had concentrations that were greater than the secondary maximum containment levels. Three nutrient concentrations were greater than 2 mg/L, a level that might indicate contamination from human activities, and one nutrient concentration (that for nitrite plus nitrite as nitrogen) was greater than the maximum contaminant level of 10 mg/L for drinking water. The median concentration for DOC was 0.5 mg/L, indicating naturally-occurring DOC conditions in the study area. Thirteen pesticides and 7 pesticide degradation products were detected in 14 of the 27 wells sampled. Bentazon, 2, 4-D, and molinate (three rice herbicides) were detected in water from four, one, and one wells, respectively, and malathion (a rice insecticide) was deteced in water fromone well. Low-level concentrations and few detections of nutrients and pesticides indicated that ground-water quality was affected slightly by anthropogenic activities. Quality-control samples, including field blanks, replicates, and spikes, indicated no bias in ground-water data from collection on analysis. Radon concentrations for 22 of the 24 wells sampled wer at or greater than the U.S. Environmental Protection Agency proposed maximum contaminant level of 300 picocuries per liter. Chlorofluorocarbon concentrations in selected wells indicated the apparent ages of the ground water varied with depth water level and ranged from about 17 to 49 years. The stable isotopes of hydrogen and oxygen in water molecules indicated the origin of ground water in the study area was rainwater that originated near the study area and that few geochemical or physical processes influenced the stable isotopic composition of the shallow ground water. The Spearman rank correlation was used to detemrine whther significant correlations existed between physical properties, selected chemical constituents, the number of pesticides detected, and the apparent age of water. The depth to ground water was positively correlated to the well depth and inversely correlated to dissolved solids and other constituents, such as radon, indicating the ground water was under unconfined or semiconfined conditions and more dilute with increasing depth. As the depth to ground water increased, the concentrations of dissolved solids and other constituents decreased, possibly because the deeper sands had a greater transmittal of ground water, which, over time, would flush out, or dilute, the concentrations of dissolved solids in the natural sediments. The apparent age of water was correlated inversely with nitrite plus nitrite concentration, indicating that as apparent age increased, the nitrite plus nitrite concentration decreased. No significant correlations existed between the number of pesticides detected and any of the physical or chemica

Water-Resources Investigations Report↗