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At least 775 records · Page 43Linked to original sources

USGS2007

Recharge area, base-flow and quick-flow discharge rates and ages, and general water quality of Big Spring in Carter County, Missouri, 2000-04

Exploration for lead deposits has occurred in a mature karst area of southeast Missouri that is highly valued for its scenic beauty and recreational opportunities. The area contains the two largest springs in Missouri (Big Spring and Greer Spring), both of which flow into federally designated scenic rivers. Concerns about potential mining effects on the area ground water and aquatic biota prompted an investigation of Big Spring. Water-level measurements made during 2000 helped define the recharge area of Big Spring, Greer Spring, Mammoth Spring, and Boze Mill Spring. The data infer two distinct potentiometric surfaces. The shallow potentiometric surface, where the depth-to-water is less than about 250 feet, tends to mimic topographic features and is strongly controlled by streams. The deep potentiometric surface, where the depth-to-water is greater than about 250 feet represents ground-water hydraulic heads within the more mature karst areas. A highly permeable zone extends about 20 mile west of Big Spring toward the upper Hurricane Creek Basin. Deeper flowing water in the Big Spring recharge area is directed toward this permeable zone. The estimated sizes of the spring recharge areas are 426 square miles for Big Spring, 352 square miles for Greer Spring, 290 square miles for Mammoth Spring, and 54 square miles for Boze Mill Spring. A discharge accumulation curve using Big Spring daily mean discharge data shows no substantial change in the discharge pattern of Big Spring during the period of record (water years 1922 through 2004). The extended periods when the spring flow deviated from the trend line can be attributed to prolonged departures from normal precipitation. The maximum possible instantaneous flow from Big Spring has not been adequately defined because of backwater effects from the Current River during high-flow conditions. Physical constraints within the spring conduit system may restrict its maximum flow. The largest discharge measured at Big Spring during the period of record (water years 1922 through 2004) was 1,170 cubic feet per second on December 7, 1982. The daily mean water temperature of Big Spring was monitored during water years 2001 through 2004 and showed little variability, ranging from 13 to 15° C (degree Celsius). Water temperatures generally vary less than 1° C throughout the year. The warmest temperatures occur during October and November and decrease until April, indicating Big Spring water temperature does show a slight seasonal variation. The use of the traditional hydrograph separation program HYSEP to determine the base flow and quick flow or runoff components at Big Spring failed to yield base-flow and quick-flow discharge curves that matched observations of spring characteristics. Big Spring discharge data were used in combination with specific conductance data to develop an improved hydrograph separation method for the spring. The estimated annual mean quick flow ranged from 15 to 48 cubic feet per second for the HYSEP analysis and ranged from 26 to 154 cubic feet per second for the discharge and specific conductance method for water years 2001 to 2004. Using the discharge and specific conductance method, the estimated base-flow component rises abruptly as the spring hydrograph rises, attains a peak value on the same day as the discharge peak, and then declines abruptly from its peak value. Several days later, base flow begins to increase again at an approximately linear trend, coinciding with the time at which the percentage of quick flow has reached a maximum after each recharge-induced discharge peak. The interval between the discharge peak and the peak in percentage quick flow ranges from 8 to 11 days for seven hydrograph peaks, consistent with quick-flow traveltime estimates by dye-trace tests from the mature karst Hurricane Creek Basin in the central part of the recharge area. Concentrations of environmental tracers chlorofluorocarbons (CFCs: CFC-11, CFC-12, CFC-113), and sulfur hexafluoride in discharge from Big Spring vary approximately linearly with percent quick flow from about 5 to 45 percent of discharge. Linear extrapolation to 100 percent quick flow implies CFC and SF 6 concentrations nearly identical to those in the 2002 atmosphere and indicates a modern age for the quick-flow component. Tracer concentrations for less than about 5 percent quick flow are increasingly lower than those expected from linear extrapolation to zero percent quick flow, indicating that the reservoir of older water in the Big Spring watershed may be a series of water mixtures with piston-flow ages greater than those obtained by extrapolation to zero percent quick flow. Each sample point with a low percentage of quick flow (less than 5 percent) may be a unique mixture. Environmental tracer data from Big Spring plot intermediate to the simple binary mixing of modern and old, pre-tracer water and results from the exponential mixture model. The mean ages of waters in the base-flow component approximately range from 30 to 200 years. The mean age of the base-flow component is youngest (30 to 40 years) in samples containing the highest quick-flow component (45 percent quick flow) and increases to 200 years or more as the fraction of quick flow decreases to less than 5 percent. Tritium data are consistent with a model of dilution of a modern component with an old, pre-tracer component and indicates that the old fraction is mostly pre-1960s in age with mean residence time of more than several hundred years. All of the samples from Big Spring and Greer Spring have water temperatures warmer than their nitrogen-argon recharge temperature, which range from approximately 10.5 to 14° C, suggesting recharge to the Big Spring watershed occurs primarily in late winter to early spring. The water temperatures at Big Spring are consistent with relatively shallow circulation (less than about 600 feet), and the water does not appear to be warmed by deep circulation along a geothermal gradient. Specific conductance values and concentrations of most inorganic constituents in water samples from Big Spring generally decrease with increasing discharge because of dilution with quick-flow water of lower ionic strength. Concentrations of some constituents such as chloride and nitrite plus nitrate, and fecal coliform densities, however, did not decrease with increasing discharge, indicating that quick flow probably is a more important source of these constituents compared to base flow. Water samples from Big Spring plot along the line of dolomite dissolution by carbonic acid, are at equilibrium with dolomite and calcite, and have a molar ratio of Ca:Mg of near 1, indicating dissolution of the mineral dolomite as the primary control on concentrations of calcium, magnesium, and bicarbonate. The flux of calcium and magnesium from Big Spring represents the dissolution of about 1,950 cubic feet of dolomite per day. The suspended sediment load of Big Spring was estimated to range from about 1 to about 70 tons per day, and the sediment load during base-flow periods ranged from about 1 to about 7 tons per day.

Missouri↗

USGS2005

Arsenic in ground water of the United States: occurrence and geochemistry

Concentrations of naturally occurring arsenic in ground water vary regionally due to a combination of climate and geology. Although slightly less than half of 30,000 arsenic analyses of ground water in the United States were 1 μg/L, about 10% exceeded 10 μg/L. At a broad regional scale, arsenic concentrations exceeding 10 μg/L appear to be more frequently observed in the western United States than in the eastern half. Arsenic concentrations in ground water of the Appalachian Highlands and the Atlantic Plain generally are very low ( 1 μg/L). Concentrations are somewhat greater in the Interior Plains and the Rocky Mountain System. Investigations of ground water in New England, Michigan, Minnesota, South Dakota, Oklahoma, and Wisconsin within the last decade suggest that arsenic concentrations exceeding 10 μg/L are more widespread and common than previously recognized. Arsenic release from iron oxide appears to be the most common cause of widespread arsenic concentrations exceeding 10 μg/L in ground water. This can occur in response to different geochemical conditions, including release of arsenic to ground water through reaction of iron oxide with either natural or anthropogenic (i.e., petroleum products) organic carbon. Iron oxide also can release arsenic to alkaline ground water, such as that found in some felsic volcanic rocks and alkaline aquifers of the western United States. Sulfide minerals are both a source and sink for arsenic. Geothermal water and high evaporation rates also are associated with arsenic concentrations 10g/L in ground and surface water, particularly in the west. Arsenic release from iron oxide appears to be the most common cause of widespread arsenic concentrations exceeding 10 µg/L a ground water. This can occur in response to different geochemical conditions, including release of arsenic to ground water through reaction of iron oxide with either natural or anthropogenic (i.e., petroleum products) organic carbon. Iron oxide also can release arsenic to alkaline ground water, such as that found in some felsic volcanic rocks and alkaline aquifers of the Western United States. Sulfide minerals are both a source and sink for arsenic. Geothermal water and high evaporation rates also are associated with arsenic concentrations ≥ 10g/L in ground and surface water, particularly in the west.

Ground Water↗

USGS1997

Ground-water flow in the Saginaw aquifer in the vicinity of the north Lansing well field, Lansing Michigan — Part 2, simulations with a regional model using a reduced cell size

Vinyl chloride has been detected in water from the Saginaw aquifer near Lansing Board of Water and Light wells in the north Lansing well field. These public-supply wells have the potential to withdraw contaminated ground water. The effects of reduced grid spacing for the existing TriCounty regional ground-water-flow model on local ground-water movement were investigated. This refinement of the grid eliminated multiple wells in a cell and reduced the number of wells represented as weak sinks. Two pumping scenarios were developed to investigate the effects of pumping conditions, plume size, and hypothetical purge well locations on the movement of the vinyl chloride plume in the Saginaw aquifer. Under 1995 pumping conditions, water that originates in the central portion of the Saginaw aquifer known to be contaminated with vinyl chloride is prevented from reaching Lansing Board of Water and Light supply wells when hypothetical purge wells located west of the plume are simulated as pumping either 100 gallons per minute or 200 gallons per minute. Purge wells located north of the plume are effective at preventing contamination from reaching Lansing Board of Water and Light supply wells when simulated as pumping 200 gallons per minute. Water that originates within and surrounding the area known to be contaminated with vinyl chloride is not prevented from reaching Lansing Board of Water and Light supply wells under 1995 conditions using either purge well location or pumping rate. Under 1997 pumping conditions, water that originates in the central portion of the Saginaw aquifer known to be contaminated with vinyl chloride is prevented from reaching Lansing Board of Water and Light supply wells when hypothetical purge wells located either west or north of the plume are simulated as pumping 200 gallons per minute. Water that originates within and surrounding the area known to be contaminated with vinyl chloride is not prevented from reaching Lansing Board of Water and Light supply wells under 1997 conditions using either purge well location or pumping rate.

Michigan↗

USGS1993

Water quality of Corydon Reservoir before implementation of agricultural best-management practices in the basin, Wayne County, Iowa, September 1990 to September 1991

A hydrologic investigation to define the water quality of Corydon Reservoir before implementation of agricultural best-management practices in the basin was conducted from September 1990 to September 1991. Runoff from the 1,680-acre basin is the primary source of water to the 58-acre reservoir. Current water quality of the reservoir is affected substantially by runoff from the agricultural basin. Total-solids, total-nitrogen, and total-phosphorus concentrations were largest during April through July 1991, the months of greatest rainfall. Herbicide concentrations increased substantially in June after application. The concentration of the sum of all triazines was greater than 50 micrograms per liter in one sample, with the predominant herbicides being atrazine and cyanazine. Atrazine concentrations, estimated from immunoassay, were greater than 8.0 micrograms per liter from June through September 1991 as a result of reservoir storage. Atrazine concentrations commonly were less at the surface than at depth. Algal populations remained constant even though nutrient concen- trations increased during the summer months. This may be due to the presence of suspended sediment that reduces light penetration and herbicides that inhibit photosynthesis.

Iowa↗

USGS1971

Resistivity sections, upper Arkansas River basin, Colorado

A reconnaissance investigation of ground-water resources in the upper Arkansas River basin from Pueblo to Leadville is being made by the U.S. Geological Survey in cooperation with the Southeastern Colorado Water Conservancy District, and the Colorado Division of Water Resources, Colorado State Engineer. As part of the investigation, surface geophysical electrical resistivity surveys were made during the summer and fall of 1970 near Buena Vista and Westcliffe, Colo. (p1.1). The resistivity surveys were made to verify a previous gravity survey and to help locate areas where ground-water supplies might be developed. This report presents the results of the surveys in the form of two resistivity sections.

Colorado↗

USGS2017

Synoptic sampling and principal components analysis to identify sources of water and metals to an acid mine drainage stream

Combining the synoptic mass balance approach with principal components analysis (PCA) can be an effective method for discretising the chemistry of inflows and source areas in watersheds where contamination is diffuse in nature and/or complicated by groundwater interactions. This paper presents a field-scale study in which synoptic sampling and PCA are employed in a mineralized watershed (Lion Creek, Colorado, USA) under low flow conditions to (i) quantify the impacts of mining activity on stream water quality; (ii) quantify the spatial pattern of constituent loading; and (iii) identify inflow sources most responsible for observed changes in stream chemistry and constituent loading. Several of the constituents investigated (Al, Cd, Cu, Fe, Mn, Zn) fail to meet chronic aquatic life standards along most of the study reach. The spatial pattern of constituent loading suggests four primary sources of contamination under low flow conditions. Three of these sources are associated with acidic (pH <3.1) seeps that enter along the left bank of Lion Creek. Investigation of inflow water (trace metal and major ion) chemistry using PCA suggests a hydraulic connection between many of the left bank inflows and mine water in the Minnesota Mine shaft located to the north-east of the river channel. In addition, water chemistry data during a rainfall-runoff event suggests the spatial pattern of constituent loading may be modified during rainfall due to dissolution of efflorescent salts or erosion of streamside tailings. These data point to the complexity of contaminant mobilisation processes and constituent loading in mining-affected watersheds but the combined synoptic sampling and PCA approach enables a conceptual model of contaminant dynamics to be developed to inform remediation.

Environmental Science and Pollution Research↗

USGS2007

Evapotranspiration from a bulrush-dominated wetland in the Klamath Basin, Oregon

Growing-season evapotranspiration and surface energy and water balances were investigated for an extensive, bulrush-dominated wetland in the Upper Klamath National Wildlife Refuge of south-central Oregon, a semi-arid region with competing demands for scarce water resources. Turbulent fluxes of sensible and latent heat were measured by eddy covariance for 1.2 to 1.9 days during each of four site visits during late-May to mid-October 1997. Mean daytime latent heat flux and the Bowen ratio ranged from 148 to 178 W m −2 and from 0.38 to 0.51, respectively, during late May, mid-July, and late August site visits. By mid-October, when the plant canopy had senesced, daytime latent heat flux and the Bowen ratio averaged 46 W m −2 and 2.8, respectively. An hourly Penman-Monteith (PM) model that was fitted to the surface-flux data provided values for the surface resistance to water-vapor diffusion that ranged from 78 s m −1 during late August to 206 s m −1 during mid-October. Similarly, a Priestley-Taylor (PT) model provided values for the PT multiplier (a) that ranged from 0.96 during late August to 0.37 during mid-October. The PM and PT models predicted evapotranspiration totals of 560 and 480 mm, respectively, for May 28 to October 12, 1997.

Oregon↗

USGS1965

Reevaluation of the ground-water resources of Tooele Valley, Utah

This study of the geohydrology of Tooele Valley, Utah, was made by the U.S. Geological Survey in cooperation with the Utah State Engineer during the period 1958-63. The purpose of the study was to update an earlier investigation of ground water in Tooele Valley made by the Geological Survey during 1940-42 (Thomas, 1946). The construction of approximately 256 wells in the valley since 1940, many of which are large-diameter pumped wells drilled since 1950, made available new data on water levels, well discharge, and chemical quality for interpretation of ground-water conditions. New data also were available on spring discharge, streamflow, aquifer characteristics, and geologic, geophysical, and climatic conditions. The earlier report by Thomas (1946) was freely used during the preparation of this report.

Utah↗

USGS2015

Storage and mobilization of natural and septic nitrate in thick unsaturated zones, California

Mobilization of natural and septic nitrate from the unsaturated zone as a result of managed aquifer recharge has degraded water quality from public-supply wells near Yucca Valley in the western Mojave Desert, California. The effect of nitrate storage and potential for denitrification in the unsaturated zone to mitigate increasing nitrate concentrations were investigated. Storage of water extractable nitrate in unsaturated alluvium up to 160 meters (m) thick, ranged from 420 to 6600 kilograms per hectare (kg/ha) as nitrogen (N) beneath undeveloped sites, from 6100 to 9200 kg/ha as N beneath unsewered sites. Nitrate reducing and denitrifying bacteria were less abundant under undeveloped sites and more abundant under unsewered sites; however, δ 15 N–NO 3 , and δ 18 O–NO 3 data show only about 5–10% denitrification of septic nitrate in most samples—although as much as 40% denitrification occurred in some parts the unsaturated zone and near the top of the water table. Storage of nitrate in thick unsaturated zones and dilution with low-nitrate groundwater are the primary attenuation mechanisms for nitrate from septic discharges in the study area. Numerical simulations of unsaturated flow, using the computer program TOUGH2, showed septic effluent movement through the unsaturated zone increased as the number and density of the septic tanks increased, and decreased with increased layering, and increased slope of layers, within the unsaturated zone. Managing housing density can delay arrival of septic discharges at the water table, especially in layered unsaturated alluvium, allowing time for development of strategies to address future water-quality issues.

California↗

USGS2002

Interactions between surface water and ground water and effects on mercury transport in the north-central Everglades

The hydrology of the north-central Everglades was altered substantially in the past century by canal dredging, land subsidence, ground-water pumping, and levee construction. Vast areas of seasonal and perennial wetlands were converted to uses for agriculture, light industry, and suburban development. As the catchment area for the Everglades decreased, so did the sources of water from local precipitation and runoff from surrounding uplands. Partly in response to those alterations, water-resources managers compartmentalized the remaining wetlands in the north-central Everglades into large retention basins, called Water Conservation Areas (WCAs). In spite of efforts to improve how water resources are managed, the result has been frequent periods of excessive drying out or flooding of the WCAs because the managed system does not have the same water-storage capacity as the pre-drainage Everglades. Linked to the hydrological modifications are ecological changes including large-scale invasions of cattail, loss of tree islands, and diminishing bird populations in the Everglades. Complex interactions among numerous physical, chemical, and biological factors are responsible for the long-term degradation of the ecological character of the Everglades.Over the past 15 years, a new set of smaller wetland basins, called Stormwater Treatment Areas (STAs), have been designed and constructed by water-resources engineers on the former wetlands adjacent to WCAs. The purpose of STAs is to remove excess nutrients from agricultural drainage water prior to its input to WCAs. STAs tend to be about one-tenth the size of a WCA, and they are located on former wetlands on the northwestern side of WCAs on sites that were managed as farmland for much of the twentieth century in an area referred to as the Everglades Agricultural Area, or EAA. The objective of the present investigation was to quantify interactions between surface water and ground water in the Everglades Nutrient Removal Project (ENR), a prototype project for the STAs that began operation in 1994. Determining the effect of ground water on the mercury balance of the ENR treatment wetland was an important additional objective. In order to broaden the relevance of conclusions to all parts of the north-central Everglades, interactions between surface water and ground water and mercury also were investigated in Water Conservation Area 2A (WCA-2A) and, to a lesser extent, in two other WCA basins, WCA-2B and WCA-3A.An important conclusion of this study is that creation of the WCA basins, and accompanying water-resources management, have appreciably increased both recharge and discharge in the north-central Everglades compared with pre-drainage conditions. Recharge and discharge are highest near the northern and northwestern edges of the Everglades, in the relatively small basins such as ENR and the STAs that share borders with both WCA-1 and the EAA. All basins experienced greater increases in recharge relative to discharge, because of the effects that land subsidence and ground-water pumping outside the Everglades had on hydraulic gradients. The highest basin-wide estimate of recharge was measured in ENR, where recharge averaged 0.9 centimeter per day (cm/d) over a 4-year study period. For perspective, that estimate of recharge is the equivalent of 30 percent of pumped surface-water inflows and 230 percent of average daily precipitation in ENR. Ground-water discharge was 10 times smaller than recharge at ENR. The present study estimated a basin-averaged recharge for WCA-2A (0.2 cm/d) that was a factor of 4 smaller than ENR. Although preliminary, that estimate of recharge is 5 times higher than previous estimates (approximately 0.04 cm/d), probably because the newer measurements were able to quantify recharge and discharge at finer spatial and temporal scales. Recharge at WCA-2A is smaller than ENR because WCA-2A has a smaller topographic gradient (3 x 10-5 and 2 x 10-4 in WCA-2A and ENR, respective

Florida↗

USGS1948

Ground water in the East Shore area, Utah. Part I. Bountiful District, Davis County

The Bountiful district in Davis County, Utah, less than 10 miles from the heart of Salt Lake City, is rapidly becoming an integral part of the metropolitan area of Salt Lake City. It cannot achieve the development that its location merits unless the present water supplies are increased. The district is a fertile agricultural area favorably situated between the largest cities in the intermountain area and athwart the major routes of transportation and communication, but development of its residential, industrial, and agricultural potentialities will be restricted until existing water resources are supplemented by importation from other drainage basins that now have surplus water supplies. This conclusion is reached in the accompanying report by the Geological Survey, prepared in cooperation with the Utah State Engineer and the Davis County Water Users Association, and based on a 2-year investigation of the existing water supplies

Utah↗

USGS2023

James Tributary summary: A summary of trends in tidal water quality and associated factors, 1985-2021

The James Tributary Summary outlines change over time for a suite of monitored tidal water quality parameters and associated potential drivers of those trends for the period 1985 – 2021 and provides a brief description of the current state of knowledge explaining these observed changes. Water quality parameters described include surface (above pycnocline) total nitrogen (TN), surface total phosphorus (TP), surface water temperature (WTEMP), spring and summer (June, July, August) surface chlorophyll a, summer bottom (below pycnocline) dissolved oxygen (DO) concentrations, and Secchi disk depth (a measure of water clarity). Results for annual bottom TP, bottom TN, surface ortho-phosphate (PO4), surface dissolved inorganic nitrogen (DIN), surface total suspended solids (TSS), and summer surface DO concentrations are provided in an Appendix. Drivers discussed include physiographic watershed characteristics, changes in TN, TP, and sediment loads from the watershed to tidal waters, expected effects of changing land use, and implementation of nutrient management and natural resource conservation practices. Factors internal to estuarine waters that also play a role as drivers are described including biogeochemical processes, physical forces such as wind-driven mixing of the water column and increase in rainfall intensity and volume, and biological factors such as phytoplankton biomass and the presence of submerged aquatic vegetation. Continuing to track water quality response and investigating these influencing factors are important steps to understanding water quality patterns and changes in the James River. The intended audiences for this report include, but are not limited to, 1) technical managers within jurisdictions who are looking at tidal water quality data and trying to understand why patterns are occurring, 2) local watershed organizations that are trying to understand these analyses and working to connect them to their local area(s), and 3) federal, state, and academic researchers. Figure 1 presents a conceptual model highlighting these intended audiences. Our goal is for the Tributary Summary documents to be sources of readily available background for change over time in tidal water quality observed with monitoring data. The intended purpose of the Tributary Summary documents is to help answer questions related to water quality, show how landscape factors drive water quality change over time, provide support for management decisions that may alter water quality trends and living resources conditions, and highlight where there may be information or knowledge gaps.

Virginia↗

USGS2024

Rappahannock tributary summary: A summary of trends in tidal water quality and associated factors, 1985-2022

The Rappahannock Tributary Summary outlines change over time for a suite of monitored tidal water quality parameters and associated potential drivers of those trends for the period of 1985 to 2022, and provides a brief description of the current state of knowledge explaining these observed changes. Water quality parameters described include surface (above pycnocline) total nitrogen (TN), surface total phosphorus (TP), surface water temperature (WTEMP), spring (March-May) and summer (JulySeptember) surface chlorophyll a, summer bottom (below pycnocline) dissolved oxygen (DO) concentrations, and Secchi disk depth (a measure of water clarity). Results for annual bottom TP, bottom TN, surface ortho-phosphate (PO 4 ), surface dissolved inorganic nitrogen (DIN), surface total suspended solids (TSS), and summer surface DO concentrations are provided in Appendix B. Drivers discussed include physiographic watershed characteristics, changes in TN, TP, and sediment loads from the watershed to tidal waters, expected effects of changing land use, and implementation of nutrient management and natural resource conservation practices. Factors internal to estuarine waters that also play a role as drivers are described including biogeochemical processes, physical forces such as winddriven mixing of the water column and increase in rainfall intensity and volume, and biological factors such as phytoplankton biomass and the presence of submerged aquatic vegetation. Continuing to track water quality response and investigating these influencing factors are important steps to understanding water quality patterns and changes in the Rappahannock River. The intended audiences for this report include, but are not limited to, 1) technical managers within jurisdictions who are looking at tidal water quality data and trying to understand why patterns are occurring, 2) local watershed organizations that are trying to understand these analyses and working to connect them to their local area(s), and 3) federal, state, and academic researchers. Figure 1 presents a conceptual model highlighting these intended audiences. Our goal is for the Tributary Summary documents to be sources of readily available background for change over time in tidal water quality observed with monitoring data. The intended purpose of the Tributary Summary documents is to help answer questions related to water quality, show how landscape factors drive water quality change over time, provide support for management decisions that may alter water quality trends and living resources conditions, and highlight where there may be information or knowledge gaps.

Virginia↗

USGS2025

Potomac Tributary Summary: A summary of trends in tidal water quality and associated factors, 1985 - 2022

The Potomac Tributary Summary outlines change over time for a suite of monitored tidal water quality parameters and associated potential drivers of those trends for the period of 1985 to 2022, and provides a brief description of the current state of knowledge explaining these observed changes. Water quality parameters described include surface (above pycnocline) total nitrogen (TN), surface total phosphorus (TP), surface water temperature (WTEMP), spring (March-May) and summer (July-September) surface chlorophyll a, summer bottom (below pycnocline) dissolved oxygen (DO) concentrations, and Secchi disk depth (a measure of water clarity). Results for annual bottom TP, bottom TN, surface ortho-phosphate (PO4), surface dissolved inorganic nitrogen (DIN), surface total suspended solids (TSS), and summer surface DO concentrations are provided in Appendix B. Drivers discussed include physiographic watershed characteristics, changes in TN, TP, and sediment loads from the watershed to tidal waters, expected effects of changing land use, and implementation of nutrient management and natural resource conservation practices. Factors internal to estuarine waters that also play a role as drivers are described including biogeochemical processes, physical forces such as wind driven mixing of the water column and increase in rainfall intensity and volume, and biological factors such as phytoplankton biomass and the presence of submerged aquatic vegetation. Continuing to track water quality response and investigating these influencing factors are important steps to understanding water quality patterns and changes in the Potomac River. The intended audiences for this report include, but are not limited to, 1) technical managers within jurisdictions who are looking at tidal water quality data and trying to understand why patterns are occurring, 2) local watershed organizations that are trying to understand these analyses and working to connect them to their local area(s), and 3) federal, state, and academic researchers. Figure 1 presents a conceptual model highlighting these intended audiences. Our goal is for the Tributary Summary documents to be sources of readily available background for change over time in tidal water quality observed with monitoring data. The intended purpose of the Tributary Summary documents is to help answer questions related to water quality, show how landscape factors drive water quality change over time, provide support for management decisions that may alter water quality trends and living resources conditions, and highlight where there may be information or knowledge gaps.

Maryland, Pennsylvania, Virginia, West Virginia↗

USGS2026

Lower Eastern Shore Tributary summary: A summary of trends in tidal water quality and associated factors, 1985-2023

The Lower Eastern Shore Tributary Summary outlines change over time according to a suite of monitored tidal water quality parameters and associated potential drivers of those trends for the period 1985 – 2023, and provides a brief description of the current state of knowledge explaining these observed changes. Water quality parameters described include surface (above pycnocline) total nitrogen (TN), surface total phosphorus (TP), surface water temperature (WTEMP), spring (March-May) and summer (July-September) surface chlorophyll a, summer bottom (below pycnocline) dissolved oxygen (DO) concentrations, and Secchi disk depth (a measure of water clarity). Results for annual bottom TP, bottom TN, surface ortho-phosphate (PO4), surface dissolved inorganic nitrogen (DIN), surface total suspended solids (TSS), and summer surface DO concentrations are provided in an Appendix B. Drivers discussed include physiographic watershed characteristics, changes in TN, TP, and sediment loads from the watershed to tidal waters, expected effects of changing land use, and implementation of nutrient management and natural resource conservation practices. Factors internal to estuarine waters that also play a role as drivers are described including biogeochemical processes, physical forces such as winddriven mixing of the water column and increase in rainfall intensity and volume, and biological factors such as phytoplankton biomass and the presence of submersed aquatic vegetation. Continuing to track water quality response and investigating these influencing factors are important steps to understanding water quality patterns and changes in the Lower Eastern Shore. The intended audiences for this report include, but are not limited to, 1) technical managers within jurisdictions who use tidal water quality to inform management decisions, 2) local watershed organizations that are trying to understand these analyses and working to connect them to their local area(s), and 3) federal, state, and academic researchers. Figure 1 presents a conceptual model highlighting these intended audiences. The Tributary Summary documents are sources of readily available background for change over time in tidal water quality observed with monitoring data. They help answer questions related to water quality, show how landscape factors drive water-quality changes over time, provide support for management decisions that may alter water quality trends and living resources conditions, and highlight where there may be information or knowledge gaps.

Maryland, Virginia↗

USGS1988

High calcium concentration in water increases mortality of salmon and trout eggs

Several experiments were conducted to investigate the effect of water chemistry during water hardening on survival of eggs of Atlantic salmon ( Salmo salar ), rainbow trout ( Salmo gairdneri ), and. brook trout (Salvelinus fontinalis). Results of these experiments showed that survival was very low when eggs were exposed to very hard water containing high concentrations of calcium (approximately 520 mg/L or greater) during the first few hours of water hardening. Such high concentrations of calcium were associated with gypsum (calcium sulfate) in the water supply. In contrast, survival of eggs significantly increased when they were initially water‐hardened (1–3 h) in softer water (Ca concentrations, 34–64 mg/L). Incubation of eggs in high‐calcium water after the initial water‐hardening period did not significantly affect survival. Results of another experiment on water hardening of rainbow trout eggs showed a significant increase in survival when eggs were initially water‐hardened in either low‐gypsum water or in high‐gypsum water softened by ion exchange to markedly reduce the calcium; but not the sulfate, content.

Progressive Fish-Culturist↗

USGS2003

What Became of the Water on Mars?

Focuses on several exploratory missions to the planet Mars to investigate the role of water within the planet. Facts about Mars that were gathered from two National Aeronautics and Space Administration orbiters, the Mars Global Surveyor and Mars Odyssey; Features of Mars that are similar with the planet Earth; Factors that contribute to the possible existence of water in Mars; Background on the geology of Mars.

Natural History↗

USGS2014

The need for a nation‐wide program of observation‐wells

During the severe droughts of recent years almost the only water‐supplies available throughout large areas of the United States have been those obtained from underground sources. Consequently, a great interest has developed in the ground‐water resources of the country and there has been much concern lest the declining water‐levels in wells and the diminished flow of springs may be warnings of the ultimate exhaustion of our ground‐water supplies. As is well known, the United States Geological Survey has for half a century conducted investigations of the ground‐water of the country and numerous investigations have been made by State geological surveys and other agencies. However, the time is now ripe for a coordinated, continuing program to obtain systematic records of water‐levels in observation ‐ wells and correlative records of natural discharge and artificial withdrawals of ground‐water.

Eos, Transactions, American Geophysical Union↗