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At least 721 records · Page 40Linked to original sources
USGS2010

Effects of groundwater levels and headwater wetlands on streamflow in the Charlie Creek basin, Peace River watershed, west-central Florida

The Charlie Creek basin was studied from April 2004 to December 2005 to better understand how groundwater levels in the underlying aquifers and storage and overflow of water from headwater wetlands preserve the streamflows exiting this least-developed tributary basin of the Peace River watershed. The hydrogeologic framework, physical characteristics, and streamflow were described and quantified for five subbasins of the 330-square mile Charlie Creek basin, allowing the contribution of its headwaters area and tributary subbasins to be separately quantified. A MIKE SHE model simulation of the integrated surface-water and groundwater flow processes in the basin was used to simulate daily streamflow observed over 21 months in 2004 and 2005 at five streamflow stations, and to quantify the monthly and annual water budgets for the five subbasins including the changing amount of water stored in wetlands. Groundwater heads were mapped in Zone 2 of the intermediate aquifer system and in the Upper Floridan aquifer, and were used to interpret the location of artesian head conditions in the Charlie Creek basin and its relation to streamflow. Artesian conditions in the intermediate aquifer system induce upward groundwater flow into the surficial aquifer and help sustain base flow which supplies about two-thirds of the streamflow from the Charlie Creek basin. Seepage measurements confirmed seepage inflow to Charlie Creek during the study period. The upper half of the basin, comprised largely of the Upper Charlie Creek subbasin, has lower runoff potential than the lower basin, more storage of runoff in wetlands, and periodically generates no streamflow. Artesian head conditions in the intermediate aquifer system were widespread in the upper half of the Charlie Creek basin, preventing downward leakage from expansive areas of wetlands and enabling them to act as headwaters to Charlie Creek once their storage requirements were met. Currently, the dynamic balance between wetland storage, rainfall-runoff processes, and groundwater-level differences in the upper basin allow it to generate approximately half of the streamflow from the Charlie Creek basin. Therefore, future development in the upper basin that would alter the hydraulic connectivity of wetlands during high flow conditions or expand recharging groundwater conditions could substantially affect streamflow in Charlie Creek. LIDAR (Light detection and ranging) based topographic maps and integrated modeling results were used to quantify the water stored in wetlands and other topographic depressions, and to describe the network of shallow stream channels connecting wetlands to Charlie Creek and its tributaries over distances of several thousand feet. Peak flows at all but one streamflow station were underpredicted in MIKE SHE simulations, possibly because the hydraulics of surface channels connecting wetlands to stream channels were not explicitly simulated in the model. Explicitly simulating the smaller channels connecting wetlands and stream channels should improve the ability of future watershed models to simulate peak flows in streams with headwater wetlands. The runoff potential was greater in the lower half of the Charlie Creek basin than in the upper half, and the streambed of Charlie Creek had greater potential to both directly gain streamflow from groundwater and lose streamflow to groundwater. Charlie Creek is more incised into the surficial aquifer in the lower basin than in the upper basin, and the streambed intersects the top of the intermediate aquifer system at two known locations. Groundwater levels in the intermediate aquifer system varied widely in the lower half of the basin from artesian conditions inducing upward flow toward the surficial aquifer and streams, to recharging conditions allowing downward flow and stream leakage. Recharge areas were greatest in May 2004 when rainfall was at a seasonal low and irrigation pumping was at a seasonal high. Recharge conditions

Scientific Investigations Report↗
USGS2014

Equations for estimating selected streamflow statistics in Rhode Island

Regional regression equations were developed for estimating selected natural—unaffected by alteration—streamflows of specific flow durations and low-flow frequency statistics for ungaged stream sites in Rhode Island. Selected at-site streamflow statistics are provided for 41 long-term streamgages, 21 short-term streamgages, and 135 partial-record stations in Rhode Island, eastern Connecticut, and southeastern and south-central Massachusetts. The regression equations for estimating selected streamflow statistics and the at-site statistics estimated for each of the 197 sites may be used by Federal, State, and local water managers in addressing water issues in and near Rhode Island. Multiple and simple linear regression equations were developed to estimate the 99-, 98-, 95-, 90-, 85-, 80-, 75-, 70-, 60-, 50-, 40-, 30-, 25-, 20-, 15-, 10-, 5-, 2-, and 1-percent flow durations and the 7Q2 (7-day, 2-year) and 7Q10 (7-day, 10-year) low-flow-frequency statistics. An additional 49 selected statistics, for which regression equations were not developed, also were estimated for the long- and short-term streamgages and partial-record stations for flow durations between the 99.99 and 0.01 percent and for the mean annual, mean monthly, and median monthly streamflows. A total of 70 selected streamflow statistics were estimated for 41 long-term streamgages, 21 short-term streamgages, and 135 partial-record stations in and near Rhode Island. Estimates of the long-term streamflow statistics for the 21 short-term streamgages and 135 partial-record stations were developed by the Maintenance of Variance Extension, type 1 (MOVE.1), record-extension technique. The equations used to estimate selected streamflow statistics were developed by relating the 19 flow-duration and 2 low-flow-frequency statistics to 31 different basin characteristics (physical, land-cover, and climatic) at the 41 long-term and 19 of 21 short-term streamgages (a total of 60 streamgages) in and near Rhode Island. The 135 partial-record stations were not used in the regression analyses. The regression analyses were done by using a user-weighted least-squares technique in the weighted-multiple-linear regression program for the 90- to 1-percent flow-duration statistics. For the 99-, 98-, and 95-percent flow durations and the 7Q2 and 7Q10 statistics, left-censored regression analyses were used to account for zero flows at a few streamgages. The regression analyses determined that two basin characteristics—drainage area and stream density—were the only significant explanatory variables for 16 of the 19 flow-duration and the 2 low-flow regression equations. For the 10-, 15-, and 20-percent flow-duration regression equations, drainage area was the only significant explanatory variable. The standard error of the estimate for the 21 regression equations ranged from 17.58 to 141.83 percent. The 99- to 85-percent flow durations and the low-flow statistics 7Q2 and 7Q10 had the highest standard errors of the estimate, ranging from 48.68 to 141.83 percent. The standard error of the estimate for the medium- to high-flow statistics—the 80- to 1-percent flow durations—ranged from 17.58 to 37.65 percent, with the standard errors for the 60- to 1-percent flow durations all being less than about 21 percent. Data also are provided to allow the user to calculate the 90-percent prediction intervals for the 21 streamflow statistics. The equations, which are based on data from streams with little to no flow alterations, will provide an estimate of the natural flows for a selected site. They will not estimate flows for altered sites with dams, surface-water withdrawals, groundwater withdrawals (pumping wells), diversions, and wastewater discharges. If the equations are used to estimate streamflow statistics for altered sites, the user should adjust the flow estimates for the alterations. The regression equations should be used only for ungaged sites with drainage areas between 0.52 and 294 square miles and stream densities between 0.94 and 3.49 miles per square mile; these are the ranges of the explanatory variables in the equations.

Rhode Island↗
USGS2007

Investigation of Ground-Water Contamination at Solid Waste Management Unit 12, Naval Weapons Station Charleston, North Charleston, South Carolina

The U.S. Geological Survey and the Naval Facilities Engineering Command Southeast investigated natural and engineered remediation of chlorinated volatile organic compound ground-water contamination at Solid Waste Management Unit 12 at the Naval Weapons Station Charleston, North Charleston, South Carolina. The primary contaminants of interest are tetrachloroethene, 1,1,1-trichloroethane, trichloroethene, cis-1,2-dichloroethene, vinyl chloride, 1,1-dichloroethane, and 1,1-dichloroethene. In general, the hydrogeology of Solid Waste Management Unit 12 consists of a surficial aquifer, composed of sand to clayey sand, overlain by dense clay that extends from about land surface to a depth of about 8 to 10 feet and substantially limits local recharge. During some months in the summer, evapotranspiration and limited local recharge result in ground-water level depressions in the forested area near wells 12MW-12S and 12MW-17S, seasonally reflecting the effects of evapotranspiration. Changes in surface-water levels following Hurricane Gaston in 2004 resulted in a substantial change in the ground-water levels at the site that, in turn, may have caused lateral shifting of the contaminant plume. Hydraulic conductivity, determined by slug tests, is higher along the axis of the plume in the downgradient part of the forests than adjacent to the plume, implying that there is some degree of lithologic control on the plume location. Hydraulic conductivity, hydraulic gradient, sulfur-hexafluoride measurements, and historical data indicate that ground-water flow rates are substantially slower in the forested area relative to upgradient areas. The ground-water contamination, consisting of chlorinated volatile organic compounds, extends eastward in the surficial aquifer from the probable source area near a former underground storage tank. Engineered remediation approaches include a permeable reactive barrier and phytoremediation. The central part of the permeable reactive barrier along the main axis of the contaminant plume appears to be actively removing contamination; however, ground-water contamination is moving around the southern end of the permeable reactive barrier. Changes in the contaminant concentrations along the path of ground-water transport reflect a complex variety of influences. Potential influences include dechlorination, sorption and desorption, transpirative removal by trees, lateral shifting of the plume, and the presence of zones of differing concentrations possibly reflecting one or more pulse releases of contamination from the source area. Near the source area at well 12MW-10S, volatile organic compound concentrations of cis-1,2-dichlorothene, vinyl chloride, 1,1-dichloroethane, and 1,1,1-trichloroethane continued an irregular decline, while tetrachloroethene and 1,1-dichloroethene showed marked fluctuations in concentration during 2005 and 2006. Volatile organic compound concentrations at well 12MW-03S continued to show decreasing concentrations with the June 2006 concentrations being the lowest yet recorded at that well for several volatile organic compounds. Concentration and delta carbon 13 data indicate that in the upgradient part of the plume, tetrachloroethene is being degraded to trichloroethene, which is being degraded to cis-1,2-dichloroethene, and cis-1,2-dichloroethene is accumulating faster than it is being depleted. Ground-water volatile organic compound concentrations also changed in some wells in the forested area in the midpart of the plume. Increasing tetrachloroethene and decreasing trichloroethene and 1,1-dichloroethene concentrations were observed at wells 12MW-05S and 12MW-29S, possibly reflecting a lateral shift in the axis of the contamination plume or an advancing contamination pulse. Substantial decreases in contamination occur in the forested area downgradient from well 12MW-05S. Probable major loss mechanisms in this area include evapotranspiration and sorption.

North Carolina, South Carolina↗
USGS2018

Preliminary synthesis and assessment of environmental flows in the middle Verde River watershed, Arizona

A 3-year study was undertaken to evaluate the suitability of the available modeling tools for characterizing environmental flows in the middle Verde River watershed of central Arizona, describe riparian vegetation throughout the watershed, and estimate sediment mobilization in the river. Existing data on fish and macroinvertebrates were analyzed in relation to basin characteristics, flow regimes, and microhabitat, and a pilot study was conducted that sampled fish and macroinvertebrates and the microhabitats in which they were found. The sampling for the pilot study took place at five different locations in the middle Verde River watershed. This report presents the results of this 3-year study. The Northern Arizona Groundwater Flow Model (NARGFM) was found to be capable of predicting long-term changes caused by alteration of regional recharge (such as may result from climate variability) and groundwater pumping in gaining, losing, and dry reaches of the major streams in the middle Verde River watershed. Over the period 1910 to 2006, the model simulated an increase in dry reaches, a small increase in reaches losing discharge to the groundwater aquifer, and a concurrent decrease in reaches gaining discharge from groundwater. Although evaluations of the suitability of using the NARGFM and Basin Characteristic Model to characterize various streamflow intervals showed that smallerscale basin monthly runoff could be estimated adequately at locations of interest, monthly stream-flow estimates were found unsatisfactory for determining environmental flows. Orthoimagery and Moderate Resolution Imaging Spectroradiometer data were used to quantify stream and riparian vegetation properties related to biotic habitat. The relative abundance of riparian vegetation varied along the main channel of the Verde River. As would be expected, more upland plant species and fewer lowland species were found in the upper-middle section compared to the lower-middle section, and vice-versa. Vegetation changes within the upper-middle and lower-middle reaches are related to differences in climate and hydrology. In general, the riparian vegetation of the middle Verde River watershed is that of a healthy ecosystem’s mixed age, mixed patch structure, likely a result of the mostly unaltered disturbance regime. The frequency of in-river hydrogeomorphic features (pool, riffle, run) varied along the middle Verde River channel. There was a greater abundance of riffle habitat in the upper-middle reach; the lower-middle reach included more pool habitat. The Oak Creek tributary was more homogenous in geomorphic stream habitat composition than West Clear Creek, where runs dominated the upper reaches and pools dominated many of the lower reaches. On the basis of the period of record and discharges recorded at 15-minute intervals, five flows were found to reach the gravel-transport threshold. Sediment mobilization computed with flows averaged over daily time steps yielded just three flows that reached the gravel-transport threshold, and monthly averaged flows yielded none. In the middle Verde River watershed, 15-minute data should be used when possible to evaluate sediment transport in the river system. Data from more than 300 fish surveys conducted from 1992 to 2011 were analyzed using two schemes, one that divided the river into five reaches based on basin characteristics, and a second that divided the river into five reaches based on degree of flow alteration (specifically, diversions). Fish community metrics and assemblage data were used to analyze patterns of species composition and abundance in the two approaches. Overall, native and non-native species were regularly interacting and probably competing for similar resources. Fish abundances were also analyzed in response to floods and other flow metrics. Although the data are limited, native fish abundances increased more rapidly than non-native fish abundances in response to large floods. The basin-characteristic reach analysis showed native fish in greater abundance in the upper-middle reaches of the Verde River watershed and generally decreasing with downstream distance. The median relative abundance of native fish decreased by 50 percent from reach 1 to reach 5. Using the reach scheme based on degree of flow alteration, nondiverted reaches were found to have a greater abundance of native fish than diverted reaches. In heavily diverted reaches, non-native species outnumbered native species. Fish metrics and stream-flow metrics for the 30, 90, and 365-day periods before collection were computed and the results analyzed statistically. Only abundance of all fish species was associated with the 30-day flow metrics. The 90-day flow metrics were generally positively associated with fish metrics, whereas the 365-day flow metrics had more negative correlations. In particular, significant relations were found between fish metrics and the magnitude and frequency of high flows, including maximum monthly flow, median annual number of high-flow events, and median annual maximum streamflow. Native sucker (Catostomidae) populations tended to decrease in periods of extended base flow, and fish in the non-native sunfish family (Centrarchidae) decreased in periods of flashy, high magnitude flows. A pilot study surveyed fish at five locations in the upper part of the middle Verde River watershed as a means to measure microhabitat availability and quantify native and non-native fish use of that available microhabitat. Results indicated that native and non-native species exhibit some clear differences in microhabitat use. Although at least some native and non-native fish were found in each velocity, depth, and substrate category, preferential microhabitat use was common. On a percentage basis, non-native species had a strong preference for slow-moving and deeper water with silt and sand substrate, with a secondary preference for faster moving and very shallow water and a coarse gravel substrate. Native species showed a general preference for somewhat faster, moderate depth water over coarse gravel and had no clear secondary preference. Macroinvertebrate-variables index period, high-flow year, and collection location (upper-middle Verde River, lowermiddle Verde River, or Verde River tributaries) were found to be important explanatory variables in differentiating among community metrics. Overall richness (number of unique taxa), Shannon’s diversity index, and the percent of the most dominant taxa were all highly correlated, but their response to each macroinvertebrate variable was different. The percentage of mayfly (order Ephemeroptera) taxa was significantly higher in Oak Creek and the upper-middle and lower-middle Verde River reaches, locations which have higher flows and more urbanization than other reaches. When community metrics were related to hydrologic metrics, caddisfly (order Trichoptera) populations appeared to increase and mayfly populations to decrease in response to less flashy and more stable streamflows. Conversely, caddisfly populations appeared to decrease and mayfly populations to increase in response to greater flow variability. Six locations along the Verde River were sampled for macroinvertebrates as part of a pilot study associated with this report—(1) below Granite Creek, (2) near Campbell Ranch, (3) at the U.S. Geological Survey Paulden gage, (4) at the Perkinsville Bridge, (5) at the USGS Clarkdale gage, and (6) near the Reitz Ranch property. A nonmetric multidimensional scaling ordination of macroinvertebrate assemblages showed that the Verde River below Granite Creek site was different from the five other sites and that the Perkinsville Bridge and near Reitz Ranch samples had similar community structure. The near Campbell Ranch and Paulden gage locations had similar microhabitat characteristics, with the exception of riparian cover, yet the assemblage structure was very different. The different community composition at Verde River below Granite Creek was likely due to it having the smallest substrate sizes, lowest velocities, shallowest depths, and most riparian cover of the six sites.

Arizona↗
USGS2008

A comparison of runoff quantity and quality from two small basins undergoing implementation of conventional- and low-impact-development (LID) strategies: Cross Plains, Wisconsin, water years 1999–2005

Environmental managers are often faced with the task of designing strategies to accommodate development while minimizing adverse environmental impacts. Low-impact development (LID) is one such strategy that attempts to mitigate environmental degradation commonly associated with impervious surfaces. The U.S. Geological Survey, in cooperation with the Wisconsin Department of Natural Resources, studied two residential basins in Cross Plains, Wis., during water years 1999–2005. A paired-basin study design was used to compare runoff quantity and quality from the two basins, one of which was developed in a conventional way and the other was developed with LID. The conventional-developed basin (herein called “conventional basin”) consisted of curb and gutter, 40-foot street widths, and a fully connected stormwater-conveyance system. The LID basin consisted of grassed swales, reduced impervious area (32-foot street widths), street inlets draining to grass swales, a detention pond, and an infiltration basin. Data collected in the LID basin represented predevelopment through near-complete build-out conditions. Smaller, more frequent precipitation events that produced stormwater discharge from the conventional basin were retained in the LID basin. Only six events with precipitation depths less than or equal to 0.4 inch produced measurable discharge from the LID basin. Of these six events, five occurred during winter months when underlying soils are commonly frozen, and one was likely a result of saturated soil from a preceding storm. In the conventional basin, the number of discharge events, using the same threshold of precipitation depth, was 180, with nearly one-half of those resulting from precipitation depths less than 0.2 inch. Precipitation events capable of producing appreciable discharge in the LID basin were typically those of high intensity or precipitation depth or those that occurred after soils were already saturated. Total annual discharge volume measured from the conventional basin ranged from 1.3 to 9.2 times that from the LID basin. Development of the LID basin did not appreciably alter the hydrologic response to precipitation characterized during predevelopment conditions. Ninety-five percent or more of precipitation in the LID basin was retained during each year of construction from predevelopment through near-complete build-out, surpassing the 90-percent benchmark established for new development by the Wisconsin Department of Natural Resources. The amount of precipitation retained in the conventional basin did not exceed 94 percent and fell below the 90-percent standard 2 of the 6 years monitored. Much of the runoff in the LID basin was retained by an infiltration basin, the largest control structure used to mitigate storm-runoff quantity and quality. The infiltration basin also was the last best-management practice (BMP) used to treat runoff before it left the LID basin as discharge. From May 25, 2002, to September 30, 2005, only 24 of 155 precipitation events exceeded the retention/ infiltrative capacity of the infiltration basin. The overall reduction in runoff volume from these few events was 51 percent. The effectiveness of the infiltration basin decreased as precipitation intensities exceeded 0.5 inch per hour. Annual loads were estimated to characterize the overall effectiveness of low-impact design practices for mitigating delivery of total solids, total suspended solids, and total phosphorus. Annual loads of these three constituents were greater in the LID basin than in the conventional basin in 2000 and 2004. Seventy percent or more of all constituent annual loads were associated with two discharge events in 2000, and a single discharge event produced 50 percent or more of constituent annual loads in 2004. Each of these discharge events was associated with considerable precipitation depths and (or) intensities, ranging from 4.89 to 6.21 inches and from 1.13 to 1.2 inches per hour, respectively. These same storms did not contribute as much of the annual load in the conventional basin. With large storms and saturated soils, the ability of low-impact design techniques to reduce runoff, and thus constituent loads, can be greatly diminished. For both the LID and conventional basins, the temperature of runoff was largely affected by ambient air temperatures. However, the temperature of discharge from the LID basin increased upon runoff cessation. This increase is likely due to solar heating of water that is temporarily stored in the detention pond and infiltration basin.

Wisconsin↗
USGS2024

Geomorphic change, hydrology, and hydraulics of Caulks Creek, Wildwood, Missouri

Caulks Creek is a small stream that flows through the city of Wildwood in western St. Louis County, Missouri. The U.S. Geological Survey, in cooperation with the city of Wildwood, has documented historical and recent geomorphic change along Caulks Creek, simulated the hydrologic and hydraulic response of Caulks Creek to a variety of design storm scenarios, and simulated bank retreat resulting from fluvial erosion and mass failure processes. Six study reaches were selected for monitoring geomorphic change based on known locations of erosion issues documented by the city of Wildwood. Recent short-term rates and patterns of geomorphic change in the study reaches, with a focus on bank retreat, were determined from repeat terrestrial light detection and ranging surveys and field observations of the six study reaches. Historical aerial photographs of the study reaches were analyzed to determine long-term rates of bank retreat and channel widening. In general, rapid bank retreat and widening was observed at the outer banks of meander bends and where banks are unforested. Short-term bank retreat varied substantially within individual study reaches, across the study area, and during the study period from no change to as much as 16 feet of retreat between consecutive surveys (5 to 8 months). The field surveys and visual observations indicated that bank retreat occurs episodically owing to a combination of fluvial erosion and mass failure processes, as well as freezing and thawing cycles. Long-term rates of bank retreat ranged from 0.6 to 4.4 feet per year. Hydrologic and hydraulic models of Caulks Creek were used to quantify the peak, volume, and timing of the flow response and the spatial distribution of hydraulic drivers of erosion (velocity and shear stress) along Caulks Creek for design storm scenarios that represent current (as of this publication) and projected future climate. The projected climate conditions resulted in higher peak flows compared to current conditions, including 6 to 21 percent for the year 2050 and 10 to 42 percent for the year 2099 at the downstream end of the study area. Additionally, for a given design storm, projected climate change is predicted to result in faster flows with greater shear stress, as well as more within-stream variability in velocity and shear stress. Many factors affect the velocity and shear stress at a given location, but in general, somewhat fast velocities and high shear stresses tended to occur where the channel is relatively narrow and straight. The velocity and shear stress in the study reaches (known areas of widening and bank retreat) were not particularly high, at least in part owing to the relatively large widths and high sinuosity of the present-day channel in these reaches. The potential mitigating effect of adding runoff storage to the basin also was examined for a selection of design storm scenarios. Additional runoff storage was more effective at mitigating peak flows and total runoff volumes for higher-frequency, lower-intensity storms than for lower-frequency, higher-intensity storms. The additional storage also resulted in an overall reduction in velocity (by as much as 28 percent) and shear stress (by as much as 40 percent) in the study area. However, the effect of the additional storage on peak flows, total runoff volumes, velocity, and shear stress decreased with distance downstream through the study area. For the simulated scenarios, added runoff storage was effective at mitigating the increases in peak flows, total runoff volumes, velocity, and shear stress caused by projected climate change. Lastly, the bank stability and toe erosion model (BSTEM) was used to predict bank erosion and potential bank failure surfaces at five locations along Caulks Creek for a selection of design storm scenarios. The lower-frequency, higher-magnitude design storms resulted in more bank retreat than the higher-frequency, lower-magnitude design storms, though the magnitude of the difference was site dependent. Although scenarios with additional storage were not directly simulated in BSTEM, it is likely that the additional storage would result in reduced bank retreat compared to the same design storm with existing storage, based on the hydraulic modeling results for scenarios with added runoff storage.

Missouri↗
USGS2013

Effects of surface applications of biosolids on groundwater quality and trace-element concentrations in crops near Deer Trail, Colorado, 2004-2010

The U.S. Geological Survey (USGS), in cooperation with Metro Wastewater Reclamation District (Metro District), studied biosolids composition and the effects of biosolids applications on groundwater quality and trace-element concentrations in crops of the Metro District properties near Deer Trail, Colorado, during 2004 through 2010. Priority parameters for each monitoring component included the nine trace elements regulated by Colorado for biosolids (arsenic, cadmium, copper, lead, mercury, molybdenum, nickel, selenium, and zinc); other constituents also were analyzed. All concentrations for the priority parameters in monthly biosolids samples were less than Colorado regulatory limits, and the concentrations were relatively consistent. Biosolids likely were the largest source of nitrogen and phosphorus on the Metro District properties. Plutonium isotopes were not detected in the biosolids, but many organic wastewater compounds (organic wastewater compounds: wastewater indicators, pharmaceuticals, and hormones) were detected in substantial concentrations relative to minimum reporting levels and various surface-water concentrations. Bismuth, copper, mercury, nitrogen, phosphorus, silver, biogenic sterols, detergent degradates, disinfectants, fire retardants, fragrances, pharmaceuticals, and plasticizers would be the most likely biosolids signature to indicate the presence of Metro District biosolids in soil or streambed sediment from the study area. Antimony, cadmium, cobalt, copper, molybdenum, nickel, nitrogen, phosphorus, selenium, tungsten, vanadium, zinc, detergent degradates, disinfectants, fire retardants, fragrances, pharmaceuticals or their degradates, and plasticizers would be the most likely biosolids signature for groundwater and surface water in the study area. More biosolids-signature components detected and larger concentration differences from untreated materials, baseline, and blank samples indicate more evidence of biosolids presence or effects. Although the inorganic constituent concentrations were relatively large in samples from one monitoring well, the concentrations of organic wastewater compounds in groundwater samples were not correspondingly large. Concentrations of organic wastewater compounds in the groundwater samples from all five monitoring wells were less than the minimum reporting levels with only a few detections. Some of the organic wastewater compounds detected could have anthropogenic sources that are not biosolids. Concentrations of priority parameters in groundwater varied spatially and temporally but generally were less than Colorado regulatory limits. Concentrations of dissolved nitrate, arsenic, and selenium, in addition to chloride, sulfate, total dissolved solids, boron, iron, manganese, and uranium, in samples from some wells exceeded the Colorado standards. Concentrations of dissolved nitrate (three wells), molybdenum (one well), selenium (two wells), and uranium (one well) in shallow groundwater had significant (alpha = 0.05) upward trends in some parts of the study area. The biosolids-signature results indicate that the aquifers intercepted by the five routinely sampled wells likely have received some recharge through treated (biosolids-applied) fields or biosolids-affected ponds. Adverse effects from this biosolids-related recharge range from few (if any) at one well to large and significantly (alpha = 0.05) increasing nitrate concentrations at another well. A statistical evaluation of five paired wheat-grain samples from treated (biosolids-applied) fields and untreated (control) fields did not indicate any evidence that biosolids applications significantly (alpha = 0.05 or 0.10) increased concentration of any of these constituents in wheat grain. The wheat-grain concentrations from this study were similar to those from other studies for fields in North America where no biosolids were applied. The data for the limited crop samples indicate that biosolids applications are not increasing the concentrations of arsenic, cadmium, copper, lead, mercury, molybdenum, nickel, selenium, sulfur, and zinc in mature wheat grain from the study area.

Colorado↗
USGS2019

Trends in streamflow and concentrations and flux of nutrients and total suspended solids in the Upper White River at Muncie, near Nora, and near Centerton, Indiana

The U.S. Geological Survey (USGS), in cooperation with The Nature Conservancy, completed a study to estimate and assess trends in streamflow and annual mean concentrations and flux of nutrients (nitrate plus nitrite, total Kjeldahl nitrogen, and total phosphorus) and total suspended solids at three USGS streamgages (hereafter referred to as “study gages”) on the Upper White River at Muncie (USGS station 03347000), near Nora (USGS station 03351000), and near Centerton (USGS station 03354000), Indiana. Water-quality data used in the analyses were collected by several agencies between calendar years 1991 and 2017, and streamflow (discharge) data were collected by the USGS. For most of the water-quality constituents, there were suitable data to facilitate an analysis of the 26-year period extending from calendar years 1991 to 2017 (water years 1992 to 2017); however, shorter analytical periods were necessary for total Kjeldahl nitrogen for the study gages at Muncie and near Centerton and for total suspended solids for the study gage near Centerton. Temporal trends in streamflows at the study gages for the period extending from water years 1978 to 2017 were assessed using Exploration and Graphics for RivEr Trends (EGRET) and Mann-Kendall and Pettitt tests. With just one exception, the annual maximum and mean daily streamflows and the annual minimum 7-day mean streamflows at the study gages demonstrated upward trends (increasing streamflows) in the EGRET analyses. The exception was the annual 7-day minimum streamflow at the study gage near Nora, which indicated no trend. Mann-Kendall tests also indicated that the average trend for the annual maximum daily, annual mean daily, and annual 7-day minimum streamflow statistics between water years 1978 and 2017 was upward at each of the study gages; however, only the trends in the annual mean daily streamflows at the study gage at Muncie and the annual maximum daily streamflows at the study gages near Nora and near Centerton were statistically significant at a 0.05 probability level. The Pettitt tests indicated that a statistically significant step trend (abrupt change) in annual mean daily streamflows occurred at each of the study gages around water year 2001. The seasonal distributions of total suspended solids, total phosphorus, nitrate plus nitrite, and total Kjeldahl nitrogen concentrations at the study gages were evaluated to identify patterns and other distinguishing characteristics by examining boxplots of concentrations as a function of month of the year. Seasonal distributions of nitrate plus nitrite concentrations and total suspended solids concentrations differed from each other but were generally similar among the three study gages for a given constituent. Median concentrations of nitrate plus nitrite were highest during the January–June months, whereas median concentrations of total suspended solids were highest during June and July. Seasonal distributions of total phosphorus concentrations were similar at the study gages near Nora and near Centerton, but the seasonal distribution was noticeably different at the study gage at Muncie, which had monthly median concentrations that were substantially lower than at the two downstream study gages (near Nora and near Centerton). The seasonal distribution of total Kjeldahl nitrogen concentrations differed in pattern among the three study gages; however, in general, some of the higher monthly median total Kjeldahl nitrogen concentrations at each study gage were associated with the late spring and summer periods. The Weighted Regressions on Time, Discharge, and Season (WRTDS) method implemented in EGRET was used to estimate water-year annual mean daily concentrations and flux of nutrients and total suspended solids, as well as estimates of concentrations and flux that were “normalized” to remove the effect of year-to-year variation in streamflow. The approximate coefficients of determination for the WRTDS regression models ranged from a high of 0.82 for total phosphorus for the study gage near Centerton to a low of 0.19 for nitrate plus nitrite for the study gage near Nora. Loads and yields of total suspended solids, total phosphorus, nitrate plus nitrite, and total Kjeldahl nitrogen were estimated for analytical periods consisting of the longest periods of concurrent record at the three study gages. Loads of each of the constituents increased sequentially from the most upstream study gage to the most downstream study gage; however, the same was not true for yields. The highest yields of total suspended solids, total phosphorus, and total Kjeldahl nitrogen occurred at the most upstream study gage (at Muncie); however, the highest yield of nitrate plus nitrite occurred at the most downstream study gage (near Centerton). WRTDS bootstrap tests were used to assess the magnitude, direction, and likelihood of changes in annual flow-normalized mean daily concentrations and flux of total suspended solids, total phosphorus, nitrate plus nitrite, and total Kjeldahl nitrogen at the study gages between water years 1997 and 2017. Changes in flow-normalized concentrations and flux of the constituents between water years 1997 and 2017 were mostly downward (decreasing). The exceptions were likely to highly likely upward (increasing) changes in (1) flow-normalized annual mean daily concentration and annual flux for total suspended solids and total phosphorus at the study gage at Muncie, (2) flow-normalized annual mean daily total phosphorus concentration at the study gage near Centerton, (3) flow-normalized annual flux of total phosphorus at the study gage near Centerton, and (4) flow-normalized annual mean daily nitrate plus nitrite concentration at the study gage near Centerton. Although an upward change in flow-normalized nitrate plus nitrite concentrations was likely at the study gage near Centerton, flow-normalized annual flux of nitrate plus nitrite at that study gage was determined to have a highly likely downward change. EGRET and Exploration and Graphics for RivEr Trends Confidence Intervals (EGRETci) analyses can be used to improve our understanding of how concentrations and flux change as functions of time and streamflow, as well as provide information on how the relations between streamflow and constituent concentrations have changed within the calendar year between any 2 years included in the analyses. Examples of those uses, illustrating changes between calendar years 1992 and 2017, were given for total suspended solids concentrations at the study gage near Nora and for nitrate plus nitrite concentrations at the study gage near Centerton.

Indiana↗
USGS2007

Hydrogeology and Aquifer Storage and Recovery Performance in the Upper Floridan Aquifer, Southern Florida

Well construction, hydraulic well test, ambient water-quality, and cycle test data were inventoried and compiled for 30 aquifer storage and recovery facilities constructed in the Floridan aquifer system in southern Florida. Most of the facilities are operated by local municipalities or counties in coastal areas, but five sites are currently being evaluated as part of the Comprehensive Everglades Restoration Plan. The relative performance of all sites with adequate cycle test data was determined, and compared with four hydrogeologic and design factors that may affect recovery efficiency. Testing or operational cycles include recharge, storage, and recovery periods that each last days or months. Cycle test data calculations were made including the potable water (chloride concentration of less than 250 milligrams per liter) recovery efficiency per cycle, total recovery efficiency per cycle, and cumulative potable water recovery efficiencies for all of the cycles at each site. The potable water recovery efficiency is the percentage of the total amount of potable water recharged for each cycle that is recovered; potable water recovery efficiency calculations (per cycle and cumulative) were the primary measures used to evaluate site performance in this study. Total recovery efficiency, which is the percent recovery at the end of each cycle, however, can be substantially higher and is the performance measure normally used in the operation of water-treatment plants. The Upper Floridan aquifer of the Floridan aquifer system currently is being used, or planned for use, at 29 of the aquifer storage and recovery sites. The Upper Floridan aquifer is continuous throughout southern Florida, and its overlying confinement is generally good; however, the aquifer contains brackish to saline ground water that can greatly affect freshwater storage and recovery due to dispersive mixing within the aquifer. The hydrogeology of the Upper Floridan varies in southern Florida; confinement between flow zones is better in southwestern Florida than in southeastern Florida. Vertical hydraulic conductivity in the upper part of the aquifer also may be higher in southeastern Florida because of unconformities present at formation contacts within the aquifer that may be better developed in this area. Recovery efficiencies per cycle varied widely. Eight sites had recovery efficiencies of less than about 10 percent for the first cycle, and three of these sites had not yet achieved recoveries exceeding 10 percent, even after three to five cycles. The highest recovery efficiency achieved per cycle was 94 percent. Three southeastern coastal sites and two southwestern coastal sites have achieved potable water recoveries per cycle exceeding 60 percent. One of the southeastern coastal sites and both of the southwestern coastal sites achieved good recoveries, even with long storage periods (from 174 to 191 days). The high recovery efficiencies for some cycles apparently resulted from water banking?an operational approach whereby an initial cycle with a large recharge volume of water is followed by cycles with much smaller recharge volume. This practice flushes out the aquifer around the well and builds up a buffer zone that can maintain high recovery efficiency in the subsequent cycles. The relative performance of all sites with adequate cycle test data was determined. Performance was arbitrarily grouped into ?high? (greater than 40 percent), ?medium? (between 20 and 40 percent), and ?low? (less than 20 percent) categories based primarily on their cumulative recovery efficiency for the first seven cycles, or projected to seven cycles if fewer cycles were conducted. The ratings of three sites, considered to be borderline, were modified using the overall recharge rate derived from the cumulative recharge volumes. A higher overall recharge rate (greater than 300 million gallons per year) can improve recovery efficiency because of the water-bankin

Scientific Investigations Report↗
USGS2016

Estimating spatially and temporally varying recharge and runoff from precipitation and urban irrigation in the Los Angeles Basin, California

A daily precipitation-runoff model, referred to as the Los Angeles Basin watershed model (LABWM), was used to estimate recharge and runoff for a 5,047 square kilometer study area that included the greater Los Angeles area and all surface-water drainages potentially contributing recharge to a 1,450 square kilometer groundwater-study area underlying the greater Los Angeles area, referred to as the Los Angeles groundwater-study area. The recharge estimates for the Los Angeles groundwater-study area included spatially distributed recharge in response to the infiltration of precipitation, runoff, and urban irrigation, as well as mountain-front recharge from surface-water drainages bordering the groundwater-study area. The recharge and runoff estimates incorporated a new method for estimating urban irrigation, consisting of residential and commercial landscape watering, based on land use and the percentage of pervious land area. The LABWM used a 201.17-meter gridded discretization of the study area to represent spatially distributed climate and watershed characteristics affecting the surface and shallow sub-surface hydrology for the Los Angeles groundwater study area. Climate data from a local network of 201 monitoring sites and published maps of 30-year-average monthly precipitation and maximum and minimum air temperature were used to develop the climate inputs for the LABWM. Published maps of land use, land cover, soils, vegetation, and surficial geology were used to represent the physical characteristics of the LABWM area. The LABWM was calibrated to available streamflow records at six streamflow-gaging stations. Model results for a 100-year target-simulation period, from water years 1915 through 2014, were used to quantify and evaluate the spatial and temporal variability of water-budget components, including evapotranspiration (ET), recharge, and runoff. The largest outflow of water from the LABWM was ET; the 100-year average ET rate of 362 millimeters per year (mm/yr) accounted for 66 percent of the combined water inflow of 551 mm/yr, including 488 mm/yr from precipitation and 63 mm/yr from urban irrigation. The simulated ET rate varied from a minimum of 0 mm/yr for impervious areas to high values of more than 1,000 mm/yr for many areas, including the south-facing slopes of the San Gabriel Mountains, stream channels underlain by permeable soils and thick root zones, and pervious locations receiving inflows both from urban irrigation and surface water. Runoff was the next largest outflow, averaging 145 mm/yr for the 100-year period, or 26 percent of the combined precipitation and urban-irrigation inflow. Recharge averaged 45 mm/yr, or about 8 percent of the combined inflow from precipitation and urban irrigation. Simulation results indicated that recharge in response to urban irrigation was an important component of spatially distributed recharge, contributing an average of 56 percent of the total recharge to the eight LABWM subdomains containing the Los Angeles groundwater study area. The 100‑year average recharge rate for the eight subdomains was 41 mm/yr, or 8,473 hectare-meters per year (ha-m/yr), with urban irrigation included in the simulation compared to a recharge rate of 18 mm/yr, or 3,741 ha-m/yr, with urban irrigation excluded. In contrast to recharge, the effect of urban irrigation on runoff was slight; runoff was 72,667 ha-m/yr with urban irrigation included compared to 72,618 ha-m/yr with urban irrigation excluded, an increase of only 48 ha-m/yr (about 0.1 percent). Simulation results also indicated that potential recharge from hilly drainages outside of, but bordering and tributary to, the lower-lying area of the Los Angeles groundwater study area, in this study referred to as mountain-front recharge, could provide an important contribution to the total recharge for the groundwater basins. The time-averaged recharge rate was similar to the combined direct and mountain-front recharge components estimated in a previous study and used as input for a calibrated groundwater model. The annual (water year) recharge estimates simulated in this study, however, indicated much greater year-to-year variability, which was dependent on year-to-year variability in the magnitude and distribution of daily precipitation, compared to the previous estimates.

California↗
USGS2020

Modeling Escherichia coli in the Missouri River near Omaha, Nebraska, 2012–16

The city of Omaha, Nebraska, has a combined sewer system in some areas of the city. In Omaha, Nebr., a moderate amount of rainfall will lead to the combination of stormwater and untreated sewage or wastewater being discharged directly into the Missouri River and Papillion Creek and is called a combined sewer overflow (CSO) event. In 2009, the city of Omaha began the implementation of their Long Term Control Plan (LTCP) to mitigate the effects of CSOs on the Missouri River and Papillion Creek. As part of the LTCP, the city partnered with the U.S. Geological Survey (USGS) in 2012 to begin monitoring in the Missouri River. Since 2012, monthly discrete water-quality samples for many constituents have been collected from the Missouri River at four sites. At 3 of the 4 sites, water quality has been monitored continuously for selected constituents and physical properties. These discrete water-quality samples and continuous water-quality monitoring data (from July 2012 to 2020) have been collected to better understand the water quality of the Missouri River, how it is changing with time, how it changes upstream from the city of Omaha to downstream, and how it varies during base-flow conditions and during periods of runoff. The purpose of this report is to document the development of Escherichia coli ( E. coli ) concentration models for these four Missouri River sites. Analysis was completed using the first 5 years of data (through 2016) to determine if the current approach is sufficient to meet future analysis goals and to understand if proposed models such as Load Estimator (LOADEST) models will be able to represent water-quality changes in the Missouri River. Multiple linear regression models were developed to estimate E. coli concentration using LOADEST as implemented in the rloadest package in the R statistical software program. A set of explanatory variables, including streamflow and streamflow anomalies, precipitation, information about CSOs, and continuous water quality, were evaluated for potential inclusion in regression models. The best model at Missouri River at NP Dodge Park at Omaha, Nebr. (USGS station 412126095565201; hereafter “NP Dodge”) included basin explanatory variables of upstream antecedent precipitation index measured at Tekamah, Nebr.; decimal time; season; and turbidity. The best model at Missouri River at Freedom Park Omaha, Nebr. (USGS station 411636095535401; hereafter “Freedom Park”) included the same explanatory variables as the NP Dodge model with the addition of turbidity anomalies and flow anomalies. The best models at the two downstream sites (Missouri River near Council Bluffs, Iowa, USGS station 06610505 and Missouri River near La Platte, Nebr., USGS station 410333095530101) included the same explanatory variables as the Freedom Park model with the addition of local antecedent precipitation index as measured at Eppley Airport in Omaha, Nebr., and additional turbidity and flow anomalies. The final selected models were the best models given our modeling design constraint in which explanatory variables included in the model for the upstream site were included in the downstream models. Explanatory variables currently (2020) being collected and included in the selected models through 2016 explained 64–75 percent of the variability of E. coli concentration in the Missouri River. Explaining 64–75 percent of the variability might be considered low when working with physical constituents (total nitrogen or sediment), but with the natural variability of biological constituents such as E. coli , the uncertainty of E. coli laboratory measurements, and the added complexity of modeling in a large drainage basin with multiple sources, these results are adequate and indicate that the explanatory variables being collected and models such as LOADEST can represent water-quality changes in the Missouri River for E. coli concentration from 2012 to 2016.

Nebraska↗
USGS2012

Variability in stream chemistry in relation to urban development and biological condition in seven metropolitan areas of the United States, 1999-2004

Beginning in 1999, the U.S. Geological Survey National Water Quality Assessment Program investigated the effects of urban development on stream ecosystems in nine metropolitan study areas across the United States. In seven of these study areas, stream-chemistry samples were collected every other month for 1 year at 6 to 10 sites. Within a study area, the sites collectively represented a gradient of urban development from minimally to highly developed watersheds, based on the percentage of urban land cover; depending on study area, the land cover before urban development was either forested or agricultural. The stream-chemistry factors measured in the samples were total nitrogen, total phosphorus, chloride, and pesticide toxicity. These data were used to characterize the stream-chemistry factors in four ways (hereafter referred to as characterizations)—seasonal high-flow value, seasonal low-flow value, the median value (representing a single integrated value of the factor over the year), and the standard deviation of values (representing the variation of the factor over the year). Aquatic macroinvertebrate communities were sampled at each site to infer the biological condition of the stream based on the relative sensitivity of the community to environmental stressors. A Spearman correlation analysis was used to evaluate relations between (1) urban development and each characterization of the stream-chemistry factors and (2) the biological condition of a stream and the different characterizations of chloride and pesticide toxicity. Overall, the study areas where the land cover before urban development was primarily forested had a greater number of moderate and strong relations compared with the study areas where the land cover before urban development was primarily agriculture; this was true when urban development was correlated with the stream-chemistry factors (except chloride) and when chloride and pesticide toxicity was correlated with the biological condition. Except for primarily phosphorus in two study areas, stream-chemistry factors generally increased with urban development, and among the different characterizations, the median value typically indicated the strongest relations. The variation in stream-chemistry factors throughout the year generally increased with urban development, indicating that water quality became less consistent as watersheds were developed. In study areas with high annual snow fall, the variation in chloride concentrations throughout the year was particularly strongly related to urban development, likely a result of road salt applications during the winter. The relations of the biological condition to chloride and pesticide toxicity were calculated irrespective of urban development, but the overall results indicated that the relations were still stronger in the study areas that had been forested before urban development. The weaker relations in the study areas that had been agricultural before urban development were likely the results of biological communities having been degraded from agricultural practices in the watersheds. Collectively, these results indicated that, compared with sampling a stream at a single point in time, sampling at regular intervals during a year may provide a more representative measure of water quality, especially in the areas of high urban development where water quality fluctuated more widely between samples. Furthermore, the use of "integrated" values of stream chemistry factors may be more appropriate when assessing relations to the biological condition of a stream because the taxa composition of a biological community typically reflects the water-quality conditions over time.

Scientific Investigations Report↗
USGS2005

Hydrology and simulation of ground-water flow in Cedar Valley, Iron County, Utah

Cedar Valley, located in the eastern part of Iron County in southwestern Utah, is experiencing rapid population growth. Cedar Valley traditionally has supported agriculture, but the growing population needs a larger share of the available water resources. Water withdrawn from the unconsolidated basin fill is the primary source for public supply and is a major source of water for irrigation. Water managers are concerned about increasing demands on the water supply and need hydrologic information to manage this limited water resource and minimize flow of water unsuitable for domestic use toward present and future public-supply sources. Surface water in the study area is derived primarily from snowmelt at higher altitudes east of the study area or from occasional large thunderstorms during the summer. Coal Creek, a perennial stream with an average annual discharge of 24,200 acre-feet per year, is the largest stream in Cedar Valley. Typically, all of the water in Coal Creek is diverted for irrigation during the summer months. All surface water is consumed within the basin by irrigated crops, evapotranspiration, or recharge to the ground-water system. Ground water in Cedar Valley generally moves from primary recharge areas along the eastern margin of the basin where Coal Creek enters, to areas of discharge or subsurface outflow. Recharge to the unconsolidated basin-fill aquifer is by seepage of unconsumed irrigation water, streams, direct precipitation on the unconsolidated basin fill, and subsurface inflow from consolidated rock and Parowan Valley and is estimated to be about 42,000 acre-feet per year. Stable-isotope data indicate that recharge is primarily from winter precipitation. The chloride mass-balance method indicates that recharge may be less than 42,000 acre-feet per year, but is considered a rough approximation because of limited chloride concentration data for precipitation and Coal Creek. Continued declining water levels indicate that recharge is not sufficient to meet demand. Water levels in many areas are at or close to historic lows. In 2000, withdrawal from wells was estimated to be 36,000 acre-feet per year. About 4,000 acre-feet per year are estimated to discharge to evapotranspiration or as subsurface outflow. Prior to large-scale ground-water development, ground-water discharge by evapotranspiration and discharge to springs was much larger. Ground water along the eastern margin of the valley between Cedar City and Enoch is unsuitable for domestic use because of high dissolved-solids and nitrate concentrations. The predominant ions of Ca and SO4 in this area indicate dissolution of gypsum in the Markagunt Plateau to the east. Data collected during this study were compared to historic data; there is no evidence to indicate deterioration in ground-water quality. The spatial distribution of ground water with high nitrate concentration does not appear to be migrating beyond its previously known extent. No single source can be identified as the cause for elevated nitrate concentrations in ground water. Low nitrogen-15 values north of Cedar City indicate a natural geologic source. Higher nitrogen-15 values toward the center of the basin and associated hydrologic data indicate probable recharge from waste-water effluent. Excess dissolved nitrogen gas and low nitrate concentrations in shallow ground water indicate that denitrification is occurring in some areas. A computer ground-water flow model was developed to simulate flow in the unconsolidated basin fill. The method of determining recharge from irrigation was changed during the calibration process to incorporate more areal and temporal variability. In general, the model accurately simulates water levels and water-level fluctuations and can be considered an adequate tool to help determine the valley-wide effects on water levels of additional ground-water withdrawals and changes in water use. The model was used to simulated water-level changes caused by projecting current withdrawal rates, increased withdrawal rates, and a 10-year drought. Water levels declined 20 to 275 feet in the southern and central parts of the valley and less than 20 feet north of Enoch

Utah↗
USGS2013

Organic wastewater compounds in water and sediment in and near restored wetlands, Great Marsh, Indiana Dunes National Lakeshore, 2009–11

A cooperative investigation between the U.S. Geological Survey and the National Park Service was completed from 2009 through 2011 to understand the occurrence, distribution, and environmental processes affecting concentrations of organic wastewater compounds in water and sediment in and near Great Marsh at the Indiana Dunes National Lakeshore in Beverly Shores, Indiana. Sampling sites were selected to represent hydrologic inputs to the restored wetlands from adjacent upstream residential and less developed areas and to represent discharge points of cascading cells within the restored wetland. A multiphase approach was used for the investigation. Discrete water samples and time-integrated passive samples were analyzed for 69 organic wastewater compounds. Continuous water-level information and periodic streamflow measurements characterized flow conditions at discharge points from restored wetland cells. Wetland sediments were collected and analyzed for sorptive losses of organic wastewater compounds and to evaluate of the potential for wetland sediments to biotransform organic wastewater compounds. A total of 52 organic wastewater compounds were detected in discrete water samples at 1 or more sites. Detections of organic wastewater compounds were widespread, but concentrations were generally low and 95 percent were less than 2.1 micrograms per liter. Six compounds were detected at concentrations greater than 2.1 micrograms per liter—four fecal sterols (beta-sitosterol, cholesterol, beta-stigmastanol, and 2-beta coprostanol), one plasticizer (bis-2-ethylhex ylphthalate), and a non-ionic detergent (4-nonylphenol diethoxylate). Two 1-month deployments of time-integrative passive samplers, called polar organic chemical integrative samplers, detected organic wastewater compounds at lower concentrations than were possible with discrete water samples. Isopropyl benzene (solvent), caffeine (plant alkaloid, stimulant), and hexahydrohexamethyl cyclopentabenzopyran (fragrance) were detected in more than half of the extracts from passive samplers, but they were not detected in any discrete water sample. The Yeast Estrogen Screen assay identified measurable estrogenicity in one passive sampler extract from the most downstream wetland site in both the April and November–December 2011 deployments and in passive sampler extracts from one residential and one upstream site in the November–December 2011 deployment only. Surface-water levels in the restored wetland cells were monitored continuously using submersible pressure transducers in hand-driven well points screened in the surface water. Surface-water levels in the wetland cells responded quickly to precipitation and substantially receded within 2 days following the largest rainfall events. Seasonal patterns in water levels generally showed higher and more variable surface-water levels in the wetland cells during spring and early summer. Water levels in the wetland cells fell below the elevation of the control structures and ceased to flow over the spillways during extended dry periods (primarily late summer and early fall). Daily loads of seven organic wastewater compounds, as indicators of septic system effluent, were estimated for samples collected at wetland outlet spillways when flow measurements could be made. Median daily loads of the indicator organic wastewater compounds increased in downstream order, and the largest median loads were measured at the most downstream site. Median daily loads were higher for samples collected in spring and summer than those collected in fall, as the higher seasonal water levels increased streamflow at the wetland outlet spillways. Wetland sediment samples were analyzed for 84 organic wastewater compounds, polycyclic aromatic hydrocarbons, and semivolatile organic compounds to investigate the fate of contaminants in Great Marsh. The top five detected compounds by total mass in wetland sediment samples were beta-sitosterol, beta-stigmastanol, cholesterol, bis(2-ethylhexyl) phthalate, and phenol. Polycyclic aromatic hydrocarbons also were frequently detected in wetland sediment samples. Source apportionment of polycyclic aromatic hydrocarbon detections indicated atmospheric sources of pyrogenic compounds, rather than residential sources. Comparisons of polycyclic aromatic hydrocarbon concentrations in wetland sediment samples to sediment quality target guidelines indicated the potential for harmful effects on sediment-dwelling organisms at several sites. Biodegradation of select endocrine-disrupting compounds (17α-ethinylestradiol, 4-nonylphenol, triclocarban, and bisphenol A) in shallow wetland sediments was evaluated in laboratory experiments by using carbon-14 radiolabeled model contaminants. Substantial biodegradation of certain organic wastewater compounds were demonstrated, primarily in oxic (oxygen containing) environments. One of four modeled compounds, bisphenol A, was biodegraded in anoxic (oxygen free) environments. Only sediments collected nearest residential areas exhibited degradation of the synthetic birth control pharmaceutical, 17α-ethinylestradiol, possibly owing to adaptation and acclimation of the indigenous microbial community to septic discharge and the resultant selection of a microbial capability for biodegradation of 17α-ethinylestradiol.

Indiana↗
USGS2005

Movement of the saltwater interface in the surficial aquifer system in response to hydrologic stresses and water-management practices, Broward County, Florida

A study was conducted to evaluate the relation between water-level fluctuations and saltwater intrusion in Broward County, Florida. The objective was achieved through data collection at selected wells in Broward County and through the development of a variable-density ground-water flow model. The numerical model is representative of many locations in Broward County that contain a well field, control structure, canal, the Intracoastal Waterway, and the Atlantic Ocean. The model was used to simulate short-term movement (from tidal fluctuations to monthly changes) and long-term movement (greater than 10 years) of the saltwater interface resulting from changes in rainfall, well-field withdrawals, sea-level rise, and upstream canal stage. The SEAWAT code, which is a combined version of the computer codes, MODFLOW and MT3D, was used to simulate the complex variable-density flow patterns. Model results indicated that the canal, control structure, and sea level have major effects on ground-water flow. For periods greater than 10 years, the upstream canal stage controls the movement and location of the saltwater interface. If upstream canal stage is decreased by 1 foot (0.3048 meter), the saltwater interface takes 50 years to move inland and stabilize. If the upstream canal stage is then increased by 1 foot (0.3048 meter), the saltwater interface takes 90 years to move seaward and stabilize. If sea level rises about 48 centimeters over the next 100 year as predicted, then inland movement of the saltwater interface may cause well-field contamination. For periods less than 10 years, simulation results indicated that a 3-year drought with increased well-field withdrawals probably will not have long-term effects on the position of the saltwater interface in the Biscayne aquifer. The saltwater interface returns to its original position in less than 10 years. Model results, however, indicated that the interface location in the lower part of the surficial aquifer system takes longer than 10 years to recover from a drought. Additionally, rainfall seems to have the greatest effect on saltwater interface movement in areas some distance from canals, but the upstream canal stage has the greatest effect on the movement of the saltwater interface near canals. Field data indicated that saltwater interface movement includes short-term fluctuations caused by tidal fluctuations and long-term seasonal fluctuations. Statistical analyses of daily-averaged data indicated that the saltwater interface moves in response to pumpage, rainfall, and upstream canal stage. In areas near the canal, the saltwater interface is most affected by canal stage because water-management structures control the stage in the upstream part of the canal and allow movement of the saltwater interface. In areas away from the canal, the saltwater interface is most affected by pumpage and rainfall, depending on the location of well fields. Data analyses also revealed that rainfall changes the vertical flow direction in the Biscayne aquifer. Results from the study indicated that upstream canal stage substantially affects the long-term position of the saltwater interface in the surficial aquifer system. The saltwater interface moves faster inland than seaward because of changes in upstream canal stage. For short-term problems, such as drought, the threat of saltwater intrusion in the Biscayne aquifer does not appear to be severe if the well-field withdrawal is increased; however, this conclusion is based on the assumption that well-field withdrawals will decrease once the drought is over. Sea-level rise may be a potential threat to the water supply in Broward County as the saltwater interface moves inland toward well fields.

Florida↗
USGS2009

Occurrence of volatile organic compounds in selected urban streams in the United States, 1995-2003

As part of the U.S. Geological Survey's (USGS) National Water-Quality Assessment (NAWQA) Program, urban indicator sites were monitored to (1) characterize the stream quality from drainage basins with predominantly residential and commercial land use, and (2) determine which selected natural and anthropogenic factors affect stream quality. A total of 869 water samples were collected from 37 urban streams during 1995-2003 and were analyzed for 87 volatile organic compounds (VOCs). The occurrence of VOCs in urban streams is described in this report for (1) all samples as a single dataset, (2) all samples grouped by streamflow pentiles, and (3) all samples grouped by warmer (April through September) and cooler (October through March) months by the detection frequency and (or) concentration of (a) any VOC, (b) VOC groups, and (c) individual compounds. An assessment level of 0.02 microgram per liter (ug/L) was used to compute the detection frequencies and concentrations of VOCs. Concentrations of VOCs were compared to (1) U.S. Environmental Protection Agency's (USEPA) drinking-water Maximum Contaminant Levels (MCLs) or Drinking Water Advisories, (2) Health-Based Screening Levels (HBSLs) developed by the USGS in collaboration with the USEPA and other agencies, and (3) USEPA and Canadian aquatic-life criteria. One or more VOCs were detected in 97.1 percent of 869 samples, and one or more VOCs were detected frequently (greater than 80 percent) at all sites. The median total VOC concentration for all samples was 0.57 ug/L, and total VOC concentrations in a single sample ranged from not detected to 698 ug/L. About 85 percent of the samples contained two or more VOCs, and about one-half contained five or more VOCs. The gasoline hydrocarbons were the most frequently occurring VOC group followed by solvents, trihalomethanes (THMs), gasoline oxygenates, organic synthesis compounds, fumigants, and refrigerants. Concentration ranges for most VOC groups were distributed over at least two orders of magnitude. Fifty-seven of the 87 VOCs analyzed were detected in at least one sample at an assessment level of 0.02 ug/L. More than one-half of the 30 VOCs not detected in samples were organic synthesis compounds. Fifteen compounds had detection frequencies greater than or equal to 10 percent. With the exception of toluene and chloroform, the median concentration of each VOC for all samples was less than the assessment level. Furthermore, the median concentrations of detections for the 15 most frequently occurring VOCs ranged from 0.03 to 3.9 ug/L, and typically were less than or equal to 0.10 ug/L. The 869 samples from the 37 sites were stratified into five streamflow pentiles (less than 20, 20-less than 40, 40-less than 60, 60-less than 80, and greater than or equal to 80 percent of estimated long-term streamflow statistics) for comparison of the occurrence of VOCs. The detection frequency of one or more VOCs by streamflow pentile varied only slightly from 96.7 to 97.7 percent. The median total VOC concentrations in samples for the five streamflow pentiles ranged from 0.39 to 1.0 ug/L. Two or more VOCs were present in more than 80 percent of samples in each of the five pentiles. The gasoline hydrocarbons, solvents, THMs, and gasoline oxygenates occurred frequently (greater than 30 percent) in all streamflow pentiles, in contrast to the organic synthesis compounds, fumigants, and refrigerants that occurred less frequently in urban streams under all streamflow conditions. The median total VOC concentrations for gasoline hydrocarbons, solvents, gasoline oxygenates, and organic synthesis compounds generally increased as streamflow increased. In contrast, the median total VOC concentrations for THMs and fumigants generally decreased as streamflow increased. The median total VOC concentrations for refrigerants showed no pattern as streamflow increased. Because differences between VOC occurrence and streamflow pentiles were small for most compariso

Scientific Investigations Report↗
USGS2021

Trends in groundwater levels in and near the Rosebud Indian Reservation, South Dakota, water years 1956–2017

The U.S. Geological Survey (USGS), in cooperation with the Rosebud Sioux Tribe, completed a study to characterize water-level fluctuations in observation wells to examine driving factors that affect water levels in and near the Rosebud Indian Reservation, which comprises all of Todd County. The study investigates concerns regarding potential effects of groundwater withdrawals and climate conditions on groundwater levels within an area that includes Todd County and a surrounding area that extends 10 miles north, east, and west of the county border. Characterization of water-level fluctuations in observation wells and relative driving factors was accomplished by statistical trend analysis. Two statistical methods were used for analysis of temporal trends for climatic and hydrologic data. To determine which trend analysis to use, applicable datasets were tested for statistically significant short-term persistence (STP). In the absence of significant STP, existence of statistical trends was determined using the standard Mann-Kendall test for probability values less than or equal to 0.10 (90-percent confidence level); however, a modified Mann-Kendall test was used for datasets where statistically significant STP was detected. Trend magnitudes were computed using the Sen’s slope estimator. Monthly data from the Parameter-elevation Regressions on Independent Slopes Model (PRISM) were aggregated to obtain annual and seasonal datasets for total precipitation, minimum air temperature ( T min ), and maximum air temperature ( T max ) for the study area and a surrounding buffer area. Trend tests for total precipitation, T min , and T max were completed for annual and seasonal time series for water years 1956–2017, which is about 2 years before the earliest available water-level measurements. A 2-year offset was arbitrarily selected because scrutiny of water-level and precipitation data indicated that responses of groundwater levels for many of the observation wells lagged major changes in precipitation patterns by about 2 years. Statistically significant upward trends were detected for annual precipitation and annual T min for almost all of the study area and the surrounding buffer area. Statistically significant downward trends in T max were detected for a very small part of the study area; however, the sparse spatial coverage reduces confidence that these are true trends. Spatial distributions of statistically significant trends in seasonal climate data were generally similar to the annual trends, but with substantial differences in the spatial density of the trends. Groundwater trends for 58 observation wells were analyzed for three separate water-level parameters (minimum, median, and maximum) because wells are measured sporadically and data are biased towards more frequent measurements during periods of heaviest irrigation demand. Trends in the time series of annual precipitation (from PRISM) starting 2 years earlier than for the associated water-level trend also were analyzed for the location of each individual observation well. Sen’s slope and Mann-Kendall probability values (p-values) were computed for the three water-level parameters and for the annual precipitation time series. Graphs showing results of trend analyses for each observation well also showed changes over time in the sum of licensed groundwater withdrawals within six specified radii (0.5, 1, 2, 3, 4, and 5 miles) of each well as a qualitative indicator of proximal groundwater demand. Of all 58 observation wells considered, 28 wells had significant upward trends for at least one of the three water-level parameters, 11 wells had significant downward trends for at least one water-level parameter, and 19 wells did not have any significant trends. Significant upward trends in annual precipitation were detected for 48 of the 58 wells. Results of trend analyses likely show the effects of groundwater withdrawals on water levels in the Ogallala aquifer in areas of substantial demand. Precipitation trends are significantly upward for 43 of the 48 wells completed in the Ogallala aquifer that were analyzed. Of the 48 Ogallala aquifer wells, 24 had significant upward trends for at least one water-level parameter (17 with all 3); however, 10 wells had statistically significant downward trends for at least one water-level parameter (8 with all 3 parameters). All but one of the wells with significant downward trends are located in the south-central part of the study area where licensed irrigation withdrawals are concentrated.

South Dakota↗
USGS2006

Diffuse-flow conceptualization and simulation of the Edwards aquifer, San Antonio region, Texas

A numerical ground-water-flow model (hereinafter, the conduit-flow Edwards aquifer model) of the karstic Edwards aquifer in south-central Texas was developed for a previous study on the basis of a conceptualization emphasizing conduit development and conduit flow, and included simulating conduits as one-cell-wide, continuously connected features. Uncertainties regarding the degree to which conduits pervade the Edwards aquifer and influence ground-water flow, as well as other uncertainties inherent in simulating conduits, raised the question of whether a model based on the conduit-flow conceptualization was the optimum model for the Edwards aquifer. Accordingly, a model with an alternative hydraulic conductivity distribution without conduits was developed in a study conducted during 2004-05 by the U.S. Geological Survey, in cooperation with the San Antonio Water System. The hydraulic conductivity distribution for the modified Edwards aquifer model (hereinafter, the diffuse-flow Edwards aquifer model), based primarily on a conceptualization in which flow in the aquifer predominantly is through a network of numerous small fractures and openings, includes 38 zones, with hydraulic conductivities ranging from 3 to 50,000 feet per day. Revision of model input data for the diffuse-flow Edwards aquifer model was limited to changes in the simulated hydraulic conductivity distribution. The root-mean-square error for 144 target wells for the calibrated steady-state simulation for the diffuse-flow Edwards aquifer model is 20.9 feet. This error represents about 3 percent of the total head difference across the model area. The simulated springflows for Comal and San Marcos Springs for the calibrated steady-state simulation were within 2.4 and 15 percent of the median springflows for the two springs, respectively. The transient calibration period for the diffuse-flow Edwards aquifer model was 1947-2000, with 648 monthly stress periods, the same as for the conduit-flow Edwards aquifer model. The root-mean-square error for a period of drought (May-November 1956) for the calibrated transient simulation for 171 target wells is 33.4 feet, which represents about 5 percent of the total head difference across the model area. The root-mean-square error for a period of above-normal rainfall (November 1974-July 1975) for the calibrated transient simulation for 169 target wells is 25.8 feet, which represents about 4 percent of the total head difference across the model area. The root-mean-square error ranged from 6.3 to 30.4 feet in 12 target wells with long-term water-level measurements for varying periods during 1947-2000 for the calibrated transient simulation for the diffuse-flow Edwards aquifer model, and these errors represent 5.0 to 31.3 percent of the range in water-level fluctuations of each of those wells. The root-mean-square errors for the five major springs in the San Antonio segment of the aquifer for the calibrated transient simulation, as a percentage of the range of discharge fluctuations measured at the springs, varied from 7.2 percent for San Marcos Springs and 8.1 percent for Comal Springs to 28.8 percent for Leona Springs. The root-mean-square errors for hydraulic heads for the conduit-flow Edwards aquifer model are 27, 76, and 30 percent greater than those for the diffuse-flow Edwards aquifer model for the steady-state, drought, and above-normal rainfall synoptic time periods, respectively. The goodness-of-fit between measured and simulated springflows is similar for Comal, San Marcos, and Leona Springs for the diffuse-flow Edwards aquifer model and the conduit-flow Edwards aquifer model. The root-mean-square errors for Comal and Leona Springs were 15.6 and 21.3 percent less, respectively, whereas the root-mean-square error for San Marcos Springs was 3.3 percent greater for the diffuse-flow Edwards aquifer model compared to the conduit-flow Edwards aquifer model. The root-mean-square errors for San Antonio and San Pedro Springs were appreciably greater, 80.2 and 51.0 percent, respectively, for the diffuse-flow Edwards aquifer model. The simulated water budgets for the diffuse-flow Edwards aquifer model are similar to those for the conduit-flow Edwards aquifer model. Differences in percentage of total sources or discharges for a budget component are 2.0 percent or less for all budget components for the steady-state and transient simulations. The largest difference in terms of the magnitude of water budget components for the transient simulation for 1956 was a decrease of about 10,730 acre-feet per year (about 2 per-cent) in springflow for the diffuse-flow Edwards aquifer model compared to the conduit-flow Edwards aquifer model. This decrease in springflow (a water budget discharge) was largely offset by the decreased net loss of water from storage (a water budget source) of about 10,500 acre-feet per year.

Texas↗