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USGS2012

Effects of a drawdown on plant communities in a freshwater impoundment at Lacassine National Wildlife Refuge, Louisiana

Disturbance is an important natural process in the creation and maintenance of wetlands. Water depth manipulation and prescribed fire are two types of disturbance commonly used by humans to influence vegetation succession and composition in wetlands with the intention of improving wildlife habitat value. A 6,475-hectare (ha) impoundment was constructed in 1943 on Lacassine National Wildlife Refuge in southwest Louisiana to create freshwater wetlands as wintering waterfowl habitat. Ten years after construction of the impoundment, called Lacassine pool, was completed, refuge staff began expressing concerns about increasing emergent vegetation cover, organic matter accumulation, and decreasing area of open water within the pool. Because the presence of permanent standing water impedes actions that can address these concerns, a small impoundment within the pool where it was possible to manipulate water depth was created. The 283-ha subimpoundment called Unit D was constructed in 1989. Water was pumped from Unit D in 1990, and the unit was permanently reflooded about 3 years later. Four prescribed fires were applied during the drawdown. A study was initiated in 1990 to investigate the effect of the experimental drawdown on vegetation and soils in Unit D. Four plant community types were described, and cores were collected to measure the depth of the soil organic layer. A second study of Unit D was conducted in 1997, 4 years after the unit was reflooded, by using the same plots and similar sampling methods. This report presents an analysis and synthesis of the data from the two studies and provides an evaluation of the impact of the management techniques applied. We found that plant community characteristics often differed among the four communities and varied with time. Species richness increased in two of the communities, and total aboveground biomass increased in all four during the drawdown. These changes, however, did not persist when Unit D was reflooded; by 1997, species richness and aboveground biomass were equivalent to values before the drawdown. The change in waterfowl food value of the plant communities during the drawdown varied; it did not change in two communities, increased in one, and decreased in one. A consistent pattern noted was that waterfowl food value was higher in communities that contained open water than in those dominated by emergent plants, both soon after the drawdown was initiated in Unit D and 4 years after reflooding. A reduction in depth of the soil organic layer became apparent 20 months after drawdown was initiated, and this reduction persisted in 1997, 4 years after reflooding. A separate 2003 study on soil characteristics in Lacassine pool found that the depth to the clay layer was lower in Unit D than in the rest of the pool. We were not able to establish a cause-and-effect relation between any changes noted and the fact water levels in the unit were drawn down because the initial study in 1990 did not include control plots. Changes in vegetation and soil organic layer depth identified in Unit D may have occurred in the surrounding Lacassine pool habitat as well. Similarly, we were unable to form any conclusions about the effect of the prescribed fire treatments because there was no information on which plots were burned. Because of the known relation between anaerobic soil conditions and reduced decomposition of organic matter, however, it is likely that the drawdown in Unit D resulted in an increased decomposition rate and a reduction in the depth of the soil organic layer.

Louisiana↗

USGS2004

Water-quality, biological, and physical-habitat conditions at fixed sites in the Cook Inlet Basin, Alaska, National Water-Quality Assessment Study Unit, October 1998-September 2001

The Cook Inlet Basin study unit of the U.S. Geological Survey National Water-Quality Assessment Program comprises 39,325 square miles in south-central Alaska. Data were collected at eight fixed sites to provide baseline information in areas where no development has taken place, urbanization or logging have occurred, or the effects of recreation are increasing. Collection of water-quality, biology, and physical-habitat data began in October 1998 and ended in September 2001 (water years 1999-2001). The climate for the water years in the study may be categorized as slightly cool-wet (1999), slightly warm-wet (2000), and significantly warm-dry (2001). Total precipitation was near normal during the study period, and air temperatures ranged from modestly cool in water year 1999 to near normal in 2000, and to notably warm in 2001. Snowmelt runoff dominates the hydrology of streams in the Cook Inlet Basin. Average annual flows at the fixed sites were approximately the same as the long-term average annual flows, with the exception of those in glacier-fed basins, which had above-average flow in water year 2001. Water temperature of all streams studied in the Cook Inlet Basin remained at 0 oC for about 6 months per year, and average annual water temperatures ranged from 3.3 to 6.2 degrees Celsius. Of the water-quality constituents sampled, all concentrations were less than drinking-water standards and only one constituent, the pesticide carbaryl, exceeded aquatic-life standards. Most of the stream waters of the Cook Inlet Basin were classified as calcium bicarbonate, which reflects the underlying geology. Streams in the Cook Inlet Basin draining areas with glaciers, rough mountainous terrain, and poorly developed soils have low concentrations of nitrogen, phosphorus, and dissolved organic carbon compared with concentrations of these same constituents in streams in lowland or urbanized areas. In streams draining relatively low-lying areas, most of the suspended sediment, nutrients, and dissolved organic carbon are transported in the spring from the melting snowpack. The urbanized stream, Chester Creek, had the highest concentrations of calcium, magnesium, chloride, and sodium, most likely because of the application of de-icing materials during the winter. Several volatile organic compounds and pesticides also were detected in samples from this stream. Aquatic communities in the Cook Inlet Basin are naturally different than similar sites in the contiguous United States because of the unique conditions of the northern latitudes where the Cook Inlet Basin is located, such as extreme diurnal cycles and long periods of ice cover. Blue-green algae was the dominant algae found at all sites although in some years green algae was the most dominant algae. Macroinvertebrate communities consist primarily of Diptera (true flies), Ephemeroptera (mayflies), and Plecoptera (stoneflies). Lowland areas have higher abundance of aquatic communities than glacier-fed basins. However, samples from the urbanized stream, Chester Creek, were dominated by oligochaetes, a class of worms. Most of the functional feeding groups were collector-gatherers. The number of taxa for both algae and macroinvertebrates were highest in water year 2001, which may be due to the relative mild winter of 2000?2001 and the above average air temperatures for this water year. The streams in the Cook Inlet Basin typically are low gradient. Bank substrates consist of silt, clay, or sand, and bed substrate consists of coarse gravel or cobbles. Vegetation is primarily shrubs and woodlands with spruce or cottonwood trees. Canopy angles vary with the size of the stream or river and are relatively low at the smaller streams and high at the larger streams. Suitable fish habitat, such as woody debris, pools, cobble substrate, and overhanging vegetation, is found at most sites. Of the human activities occurring in the fixed site basins ? high recreational use, logging, and urbanizat

Scientific Investigations Report↗

USGS2007

Evaluation of Street Sweeping as a Stormwater-Quality-Management Tool in Three Residential Basins in Madison, Wisconsin

Recent technological improvements have increased the ability of street sweepers to remove sediment and other debris from street surfaces; the effect of these technological advancements on stormwater quality is largely unknown. The U.S. Geological Survey, in cooperation with the City of Madison and the Wisconsin Department of Natural Resources, evaluated three street-sweeper technologies from 2002 through 2006. Regenerative-air, vacuum-assist, and mechanical-broom street sweepers were operated on a frequency of once per week (high frequency) in separate residential basins in Madison, Wis., to measure each sweeper's ability to not only reduce street-dirt yield but also improve the quality of stormwater runoff. A second mechanical-broom sweeper operating on a frequency of once per month (low frequency) was also evaluated to measure reductions in street-dirt yield only. A paired-basin study design was used to compare street-dirt and stormwater-quality samples during a calibration (no sweeping) and a treatment period (weekly sweeping). The basis of this paired-basin approach is that the relation between paired street-dirt and stormwater-quality loads for the control and tests basins is constant until a major change is made at one of the basins. At that time, a new relation will develop. Changes in either street-dirt and/or stormwater quality as a result of street sweeping could then be quantified by use of statistical tests. Street-dirt samples collected weekly during the calibration period and twice per week during the treatment period, once before and once after sweeping, were dried and separated into seven particle-size fractions ranging from less than 63 micrometers to greater than 2 millimeters. Street-dirt yield evaluation was based on a computed mass per unit length of pounds per curb-mile. An analysis of covariance was used to measure the significance of the effect of street sweeping at the end of the treatment period and to quantify any reduction in street-dirt yield. Both the regenerative-air and vacuum-assist sweepers produced reductions in street-dirt yield at the 5-percent significance level. Street-dirt yield was reduced by an average of 76, 63, and 20 percent in the regenerative-air, vacuum-assist, and high-frequency broom basins, respectively. The low-frequency broom basin showed no significant reductions in street-dirt yield. Sand-size particles (greater than 63 micrometers) recorded the greatest overall reduction. Street-sweeper pickup efficiency was determined by computing the difference between weekly street-dirt yields before and after sweeping cleaning. The regenerative-air and vacuum-assist sweepers had similar pickup efficiencies of 25 and 30 percent, respectively. The mechanical broom sweeper operating at high frequency was considerably less efficient, removing an average of 5 percent of street-dirt yield. The effects of street sweeping on stormwater quality were evaluated by use of statistical tests to compare event mean concentrations and loads computed for individual storms at the control and test basins. Loads were computed by multiplying the event mean concentrations by storm-runoff volumes. Only ammonia-nitrogen for the test basin with the vacuum-assist sweeper showed significant load increases over the control basin, at the 10-percent significance level, of 63 percent. Difficulty in detecting significant changes in constituent stormwater-quality loads could be due, in part, to the large amount of variability in the data. Coefficients of variation for the majority of constituent loads were greater than 1, indicating substantial variability. The ability to detect changes in constituent stormwater-quality loads was likely hampered by an inadequate number of samples in the data set. However, sediment transport in the storm-sewer pipe, sediment washing onto the street from other source areas, winter sand application, and sampling challenges were additional sources of variability within each study ba

Scientific Investigations Report↗

USGS2012

Status of groundwater quality in the Coastal Los Angeles Basin, 2006-California GAMA Priority Basin Project

Groundwater quality in the approximately 860-square-mile (2,227-square-kilometer) Coastal Los Angeles Basin study unit (CLAB) was investigated as part of the Priority Basin Project of the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The study area is located in southern California in Los Angeles and Orange Counties. The GAMA Priority Basin Project is being conducted by the California State Water Resources Control Board in collaboration with the U.S. Geological Survey (USGS) and the Lawrence Livermore National Laboratory. The GAMA CLAB study was designed to provide a spatially unbiased assessment of the quality of untreated (raw) groundwater in the primary aquifer system. The assessment is based on water-quality and ancillary data collected in 2006 by the USGS from 69 wells and on water-quality data from the California Department of Public Health (CDPH) database. The primary aquifer system was defined by the depth interval of the wells listed in the CDPH database for the CLAB study unit. The quality of groundwater in the primary aquifer system may be different from that in the shallower or deeper water-bearing zones; shallow groundwater may be more vulnerable to surficial contamination. This study assesses the status of the current quality of the groundwater resource by using data from samples analyzed for volatile organic compounds (VOCs), pesticides, and naturally occurring inorganic constituents, such as major ions and trace elements. This status assessment is intended to characterize the quality of groundwater resources in the primary aquifer system of the CLAB study unit, not the treated drinking water delivered to consumers by water purveyors. Relative-concentrations (sample concentration divided by the health- or aesthetic-based benchmark concentration) were used for evaluating groundwater quality for those constituents that have Federal and (or) California regulatory or non-regulatory benchmarks for drinking-water quality. A relative-concentration greater than (>) 1.0 indicates a concentration greater than a benchmark, and a relative-concentration less than or equal to (≤) 1.0 indicates a concentration equal to or less than a benchmark. Relative-concentrations of organic and special-interest constituents [perchlorate, N -nitrosodimethylamine (NDMA), 1,2,3-trichloropropane (1,2,3-TCP), and 1,4-dioxane] were classified as "high" (relative-concentration>1.0), "moderate" (0.5 status assessment for evaluating regional-scale groundwater quality. High aquifer-scale proportion is defined as the percentage of the area of the primary aquifer system with a relative-concentration greater than 1.0 for a particular constituent or class of constituents; percentage is based on an areal rather than a volumetric basis. Moderate and low aquifer-scale proportions were defined as the percentage of the primary aquifer system with moderate and low relative-concentrations, respectively. Two statistical approaches-grid-based and spatially weighted-were used to evaluate aquifer-scale proportions for individual constituents and classes of constituents. Grid-based and spatially weighted estimates were comparable in the CLAB study unit (within 90-percent confidence intervals). Inorganic constituents with human-health benchmarks were detected at high relative-concentrations in 5.6 percent of the primary aquifer system and moderate in 26 percent. High aquifer-scale proportion of inorganic constituents primarily reflected high aquifer-scale proportions of arsenic (1.9 percent), nitrate (1.9 percent), and uranium (1.2 percent). Inorganic constituents with secondary maximum contaminant levels (SMCL) were detected at high relative-concentrations in 18 percent of the primary aquifer system and moderate in 47 percent. The constituents present at high relative-concentrations included total dissolved solids (1.9 percent), manganese (15 percent), and iron (9.4 percent). Relative-concentrations of organic constituents (one or more) were high in 3.7 percent, and moderate in 13 percent, of the primary aquifer system. The high aquifer-scale proportion of organic constituents primarily reflected high aquifer-scale proportions of solvents, including trichloroethene (TCE; 1.7 percent), perchloroethene (PCE; 1.1 percent), and carbon tetrachloride (1.0 percent). Of the 204 organic constituents analyzed, 44 constituents were detected. Eleven organic constituents had detection frequencies of greater than 10 percent: the trihalomethanes chloroform and bromodichloromethane, the solvents TCE, PCE, cis -1,2-dichloroethene, and 1,1-dichloroethene, the herbicides atrazine, simazine, prometon, and tebuthiuron, and the gasoline additive methyl tert -butyl ether (MTBE). Most detections were at low relative-concentrations. The special-interest constituent perchlorate was detected at high relative-concentrations in 0.5 percent of the primary aquifer system, and at moderate relative-concentrations in 35 percent. The special-interest constituent 1,4-dioxane was detected at high relative-concentrations, but an insufficient number of samples was analyzed to provide a representative estimate of aquifer-scale proportion.

California↗

USGS2007

Ground-Water Quality and Potential Effects of Individual Sewage Disposal System Effluent on Ground-Water Quality in Park County, Colorado, 2001-2004

In 2000, the U.S. Geological Survey, in cooperation with Park County, Colorado, began a study to evaluate ground-water quality in the various aquifers in Park County that supply water to domestic wells. The focus of this study was to identify and describe the principal natural and human factors that affect ground-water quality. In addition, the potential effects of individual sewage disposal system (ISDS) effluent on ground-water quality were evaluated. Ground-water samples were collected from domestic water-supply wells from July 2001 through October 2004 in the alluvial, crystalline-rock, sedimentary-rock, and volcanic-rock aquifers to assess general ground-water quality and effects of ISDS's on ground-water quality throughout Park County. Samples were analyzed for physical properties, major ions, nutrients, bacteria, and boron; and selected samples also were analyzed for dissolved organic carbon, human-related (wastewater) compounds, trace elements, radionuclides, and age-dating constituents (tritium and chlorofluorocarbons). Drinking-water quality is adequate for domestic use throughout Park County with a few exceptions. Only about 3 percent of wells had concentrations of fluoride, nitrate, and (or) uranium that exceeded U.S. Environmental Protection Agency national, primary drinking-water standards. These primary drinking-water standards were exceeded only in wells completed in the crystalline-rock aquifers in eastern Park County. Escherichia coli bacteria were detected in one well near Guffey, and total coliform bacteria were detected in about 11 percent of wells sampled throughout the county. The highest total coliform concentrations were measured southeast of the city of Jefferson and west of Tarryall Reservoir. Secondary drinking-water standards were exceeded more frequently. About 19 percent of wells had concentrations of one or more constituents (pH, chloride, fluoride, sulfate, and dissolved solids) that exceeded secondary drinking-water standards. Currently (2004), there is no federally enforced drinking-water standard for radon in public water-supply systems, but proposed regulations suggest a maximum contaminant level of 300 picocuries per liter (pCi/L) and an alternative maximum contaminant level of 4,000 pCi/L contingent on other mitigating remedial activities to reduce radon levels in indoor air. Radon concentrations in about 91 percent of ground-water samples were greater than or equal to 300 pCi/L, and about 25 percent had radon concentrations greater than or equal to 4,000 pCi/L. Generally, the highest radon concentrations were measured in samples collected from wells completed in the crystalline-rock aquifers. Analyses of ground-water-quality data indicate that recharge from ISDS effluent has affected some local ground-water systems in Park County. Because roughly 90 percent of domestic water used is assumed to be recharged by ISDS's, detections of human-related (wastewater) compounds in ground water in Park County are not surprising; however, concentrations of constituents associated with ISDS effluent generally are low (concentrations near the laboratory reporting levels). Thirty-eight different organic wastewater compounds were detected in 46 percent of ground-water samples, and the number of compounds detected per sample ranged from 1 to 17 compounds. Samples collected from wells with detections of wastewater compounds also had significantly higher (p-value < 0.05) chloride and boron concentrations than samples from wells with no detections of wastewater compounds. ISDS density (average subdivision lot size used to estimate ISDS density) was related to ground-water quality in Park County. Chloride and boron concentrations were significantly higher in ground-water samples collected from wells located in areas that had average subdivision lot sizes of less than 1 acre than in areas that had average subdivision lot sizes greater than or equal to 1 acre. For wells completed in the crystalline-

Scientific Investigations Report↗

USGS2008

Simulations of Ground-Water Flow, Transport, Age, and Particle Tracking near York, Nebraska, for a Study of Transport of Anthropogenic and Natural Contaminants (TANC) to Public-Supply Wells

Contamination of public-supply wells has resulted in public-health threats and negative economic effects for communities that must treat contaminated water or find alternative water supplies. To investigate factors controlling vulnerability of public-supply wells to anthropogenic and natural contaminants using consistent and systematic data collected in a variety of principal aquifer settings in the United States, a study of Transport of Anthropogenic and Natural Contaminants to public-supply wells was begun in 2001 as part of the U.S. Geological Survey National Water-Quality Assessment Program. The area simulated by the ground-water flow model described in this report was selected for a study of processes influencing contaminant distribution and transport along the direction of ground-water flow towards a public-supply well in southeastern York, Nebraska. Ground-water flow is simulated for a 60-year period from September 1, 1944, to August 31, 2004. Steady-state conditions are simulated prior to September 1, 1944, and represent conditions prior to use of ground water for irrigation. Irrigation, municipal, and industrial wells were simulated using the Multi-Node Well package of the modular three-dimensional ground-water flow model code, MODFLOW-2000, which allows simulation of flow and solutes through wells that are simulated in multiple nodes or layers. Ground-water flow, age, and transport of selected tracers were simulated using the Ground-Water Transport process of MODFLOW-2000. Simulated ground-water age was compared to interpreted ground-water age in six monitoring wells in the unconfined aquifer. The tracer chlorofluorocarbon-11 was simulated directly using Ground-Water Transport for comparison with concentrations measured in six monitoring wells and one public supply well screened in the upper confined aquifer. Three alternative model simulations indicate that simulation results are highly sensitive to the distribution of multilayer well bores where leakage can occur and that the calibrated model resulted in smaller differences than the alternative models between simulated and interpreted ages and measured tracer concentrations in most, but not all, wells. Results of the first alternative model indicate that the distribution of young water in the upper confined aquifer is substantially different when well-bore leakage at known abandoned wells and test holes is removed from the model. In the second alternative model, simulated age near the bottom of the unconfined aquifer was younger than interpreted ages and simulated chlorofluorocarbon-11 concentrations in the upper confined aquifer were zero in five out of six wells because the conventional Well Package fails to account for flow between model layers though well bores. The third alternative model produced differences between simulated and interpreted ground-water ages and measured chlorofluorocarbon-11 concentrations that were comparable to the calibrated model. However, simulated hydraulic heads deviated from measured hydraulic heads by a greater amount than for the calibrated model. Even so, because the third alternative model simulates steady-state flow, additional analysis was possible using steady-state particle tracking to assess the contributing recharge area to a public supply well selected for analysis of factors contributing to well vulnerability. Results from particle-tracking software (MODPATH) using the third alternative model indicates that the contributing recharge area of the study public-supply well is a composite of elongated, seemingly isolated areas associated with wells that are screened in multiple aquifers. The simulated age distribution of particles at the study public-supply well indicates that all water younger than 58 years travels through well bores of wells screened in multiple aquifers. The age distribution from the steady-state model using MODPATH estimates the youngest 7 percent of the water to have a flow-weighted mean age

Scientific Investigations Report↗

USGS2023

Changes in phosphorus and suspended solids loading in the Fox River, northeastern Wisconsin, 1989–2021

The entire Lower Fox River and inner bay of Green Bay, in northeastern Wisconsin, have been listed as impaired by the Wisconsin Department of Natural Resources (WDNR) for low dissolved oxygen and degraded habitat, with total phosphorus (TP) and total suspended solids (TSS) concentrations listed as the likely causes of these impairments. To restore the Fox River and Green Bay, total maximum daily loads (TMDLs) were developed for TP and TSS, and actions were taken throughout the Fox River Basin to improve water quality. In this study, we estimated concentrations and loads of TP, dissolved phosphorus (DP), and TSS at the Lake Winnebago outlet, De Pere, and the mouth of the Fox River from water year (WY) 1989 to WY 2021; described changes in concentrations and loads through time during this period; and compared the concentrations and loads for the most recent 5-year period (WYs 2017–21) with the WDNR criteria for TP impairment and the TMDL loading goals. TP, DP, TSS, and total suspended sediment concentration data were obtained from NEW Water (the brand of the Green Bay Metropolitan Sewerage District), the WDNR, and the U.S. Geological Survey and combined into one dataset. All the TSS and total suspended sediment data were used together with no adjustment factor and are referred to as simply “TSS.” During WYs 1989–2021, mean annual TP concentrations increased from 0.089 milligram per liter (mg/L) at the Lake Winnebago outlet to 0.128 mg/L at the mouth of the Fox River, and concentrations decreased at all three sites from WY 1989 to WY 2021. The most recent (WYs 2017–21) median May–October TP concentrations were just less than the 0.1-mg/L WDNR criterion for TP impairment at the two upstream sites (Lake Winnebago outlet and De Pere) but were slightly greater than the criterion for impairment at the mouth of the Fox River. Mean annual DP concentrations increased from 0.024 mg/L at the Lake Winnebago outlet to 0.036 mg/L at the mouth of the Fox River. DP concentrations increased from WY 1989 to WY 2021 at the Lake Winnebago outlet but not at the other sites. Mean annual TSS concentrations increased from 13.5 mg/L at the Lake Winnebago outlet to 23.9 mg/L at the mouth of the Fox River and have decreased at all three sites from WY 1989 to WY 2021. The recent median May–October TSS concentrations were less than the 20-mg/L WDNR criterion for impairment at all three sites. Streamflow and TP, DP, and TSS loads increased from the Lake Winnebago outlet to the mouth of the Fox River (TP loads increased from 360,000 to 557,000 kilograms per year [kg/yr], DP loads increased from 114,000 to 162,000 kg/yr, and TSS loads increased from 60,400 metric tons per year [t/yr] to 122,600 t/yr). At the Lake Winnebago outlet, DP concentrations and TP and DP loads increased from WY 1989 to WY 2021 because of an increase in DP concentrations in Lake Winnebago resulting from the lake becoming nitrogen limited as a result of biological processes not consuming the DP in the lake and an increase in streamflow leaving the lake. Although TP and TSS concentrations decreased at De Pere and the mouth of the Fox River, there was little change in the loading because of an increase in flow. Flow-normalized TP and TSS loads at De Pere and the mouth of the Fox River decreased possibly because of implementation of agricultural conservation management practices, reductions in point-source discharges in its drainage basin, and deposition of sediment and phosphorus in recently dredged areas of the Lower Fox River. Additional studies are needed to determine the relative importance of each of these actions and whether the decrease in concentrations and flow-normalized loads will continue to be observed in the Fox River.

Wisconsin↗

USGS2007

An Assessment of Hydrology, Fluvial Geomorphology, and Stream Ecology in the Cardwell Branch Watershed, Nebraska, 2003-04

An assessment of the 16.3-square-mile Cardwell Branch watershed characterized the hydrology, fluvial geomorphology, and stream ecology in 2003-04. The study - performed by the U.S. Geological Survey in cooperation with the City of Lincoln, Nebraska, and the Lower Platte South Natural Resources District - focused on the 7.7-square-mile drainage downstream from Yankee Hill Reservoir. Hydrologic and hydraulic models were developed using the Hydrologic Modeling System (HEC-HMS) and River Analysis System (HEC-RAS) of the U.S. Army Corps of Engineers Hydraulic Engineering Center. Estimates of streamflow and water-surface elevation were simulated for 24-hour-duration design rainstorms ranging from a 50-percent frequency to a 0.2-percent frequency. An initial HEC-HMS model was developed using the standardized parameter estimation techniques associated with the Soil Conservation Service curve number technique. An adjusted HEC-HMS model also was developed in which parameters were adjusted in order for the model output to better correspond to peak streamflows estimated from regional regression equations. Comparisons of peak streamflow from the two HEC-HMS models indicate that the initial HEC-HMS model may better agree with the regional regression equations for higher frequency storms, and the adjusted HEC-HMS model may perform more closely to regional regression equations for larger, rarer events. However, a lack of observed streamflow data, coupled with conflicting results from regional regression equations and local high-water marks, introduced considerable uncertainty into the model simulations. Using the HEC-RAS model to estimate water-surface elevations associated with the peak streamflow, the adjusted HEC-HMS model produced average increases in water-surface elevation of 0.2, 1.1, and 1.4 feet for the 50-, 1-, and 0.2-percent-frequency rainstorms, respectively, when compared to the initial HEC-HMS model. Cross-sectional surveys and field assessments conducted between November 2003 and March 2004 indicated that Cardwell Branch and its unnamed tributary appear to be undergoing incision (the process of downcutting) (with three locations showing 2 or more feet of streambed incision since 1978) that is somewhat moderated by the presence of grade controls and vegetation along the channel profile. Although streambank failures were commonly observed, 96 percent of the surveyed cross sections were classified as stable by planar and rotational failure analysis-a disconnect that may have been the result of assumed soil properties. Two process-based classification systems each indicated that the reaches within the study area were incising and widening, and the Rosgen classification system characterized the streams as either type E6 or B6c. E6 channels are hydraulically efficient with low width-depth ratios, low to moderate sinuosity, and gentle to moderately steep slopes. B6c channels typically are incised with low width-depth ratios maintained by riparian vegetation, low bedload transport, and high washload transport. No obvious nickpoints (interruption or break in slope) were observed in the thalweg profile (line of maximum streambed descent), and the most acute incision occurred immediately downstream from bridges and culverts. Nine water-quality samples were collected between August 2003 and November 2004 near the mouth of the watershed. Sediment-laden rainfall-runoff substantially affected the water quality in Cardwell Branch, leading to greater biochemical and chemical oxygen demands as well as increased concentrations of several nutrient, bacteriological, sediment, and pesticide constituents. The storage of rainfall runoff in Yankee Hill Reservoir may prolong the presence of runoff-related constituents downstream. Across the study area, there was a lack of habitat availability for aquatic biota because of low dissolved oxygen levels and low streamflows or dry channels. In August 2003, the aquatic community near the mouth of

Scientific Investigations Report↗

USGS2009

Physical and Vegetative Characteristics of a Newly Constructed Wetland and Modified Stream Reach, Tredyffrin Township, Chester County, Pennsylvania, 2000-2006

To compensate for authorized disturbance of naturally occurring wetlands and streams during roadway improvements to U.S. Highway 202 in Chester and Montgomery Counties, Pa., the Pennsylvania Department of Transportation (PennDOT) constructed 0.42 acre of emergent wetland and 0.94 acre of scrub-shrub/forested wetland and modified sections of a 1,600-foot reach of Valley Creek with woody riparian plantings and streambank-stabilization structures (including rock deflectors). In accordance with project permits and additional guidance issued by the U.S. Army Corps of Engineers, the U.S. Geological Survey (USGS), in cooperation with PennDOT, collected data from 2000 through 2006 to quantify changes in 1) the vegetation, soils, and extent of emergent and scrub-shrub/forested parts of the constructed wetland, 2) the profile, dimension, and substrate in the vicinity of rock deflectors placed at two locations within the modified stream reach, and 3) the woody vegetation within the planted riparian buffer. The data for this investigation were collected using an approach adapted from previous investigations so that technology and findings may be more easily transferred among projects with similar objectives. Areal cover by planted and non-planted vegetation growing within the emergent and scrub-shrub/forested parts of the constructed wetland exceeded 85 percent at the end of each growing season, a criterion in special condition 25c in the U.S. Army Corps of Engineers project permit. Areal cover of vegetation in emergent and scrub-shrub/forested parts of the constructed wetland exceeded 100 percent in all but one growing season. Frequent and long-lasting soil saturation favored obligate-wetland species like Typha latifolia (broadleaf cattail) and Scirpus validus (great bulrush), both of which maintained dominance in the emergent wetland throughout the study (percent cover was 20 and 78 percent, respectively, in 2006). Echinocloa crusgalli (barnyard grass), an annual invasive from Eurasia, initially established in the newly disturbed soils of the scrub-shrub/forested wetland (areal cover was 56 percent in 2000), but by 2002, E. crusgalli was not growing in any sample plots and other species including Agrostis stolonifera (creeping bent grass), Festuca rubra (red fescue), Cornus spp. (dogwood species), and Salix nigra (black willow) were becoming more common. Sal. nigra contributed 30-percent cover in the scrub-shrub/forested wetland part by fall 2003. Rapid colonization of this species in subsequent years increased annual cover through 2006, when 15- to 25-foot tall Sal. nigra trees dominated the tree/shrub stratum (48 percent of the areal cover in 2006). The understory of the scrub-shrub/forested wetland was mostly shaded because of the canopy of Sal. nigra trees. Herbaceous species growing under and near the margins of the canopy included Ag. stolonifera and Ty. latifolia (29- and 23-percent areal cover, respectively). Flows in Valley Creek are responsible for transporting sediment and shaping the channel. Annual mean streamflow during the period the modified stream reach was monitored ranged from 15.2 cubic feet per second (ft3/s) in the 2002 water year to 53.0 ft3/s in the 2004 water year. This is a range of about 55 percent lower to 58 percent higher than the annual mean streamflow for the period of record. Despite the variability in streamflow, longitudinal profiles surveyed near rock deflectors in two short (100-foot) reaches within the modified stream reach maintained a constant slope throughout the monitoring period, most likely because of the presence of bedrock control. Cross-section geometry in the upstream reach was virtually unchanged during the monitoring period but 10 feet of bank migration was measured downstream, leaving the rock deflectors in mid-stream. As indicated by the change in channel morphology at the downstream reach, it is apparent that the rock deflectors were ineffective at adequately protecting the bank

Scientific Investigations Report↗

USGS2011

Status of groundwater quality in the Southern, Middle, and Northern Sacramento Valley study units, 2005-08: California GAMA Priority Basin Project

Groundwater quality in the Southern, Middle, and Northern Sacramento Valley study units was investigated as part of the Priority Basin Project of the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The study units are located in California’s Central Valley and include parts of Butte, Colusa, Glenn, Placer, Sacramento, Shasta, Solano, Sutter, Tehama, Yolo, and Yuba Counties. The GAMA Priority Basin Project is being conducted by the California State Water Resources Control Board in collaboration with the U.S. Geological Survey and the Lawrence Livermore National Laboratory. The three study units were designated to provide spatially-unbiased assessments of the quality of untreated groundwater in three parts of the Central Valley hydrogeologic province, as well as to provide a statistically consistent basis for comparing water quality regionally and statewide. Samples were collected in 2005 (Southern Sacramento Valley), 2006 (Middle Sacramento Valley), and 2007–08 (Northern Sacramento Valley). The GAMA studies in the Southern, Middle, and Northern Sacramento Valley were designed to provide statistically robust assessments of the quality of untreated groundwater in the primary aquifer systems that are used for drinking-water supply. The assessments are based on water-quality data collected by the USGS from 235 wells in the three study units in 2005–08, and water-quality data from the California Department of Public Health (CDPH) database. The primary aquifer systems (hereinafter, referred to as primary aquifers) assessed in this study are defined by the depth intervals of the wells in the CDPH database for each study unit. The quality of groundwater in shallow or deep water-bearing zones may differ from quality of groundwater in the primary aquifers; shallow groundwater may be more vulnerable to contamination from the surface. The status of the current quality of the groundwater resource was assessed by using data from samples analyzed for volatile organic compounds (VOC), pesticides, and naturally occurring inorganic constituents, such as major ions and trace elements. This status assessment is intended to characterize the quality of groundwater resources within the primary aquifers of the three Sacramento Valley study units, not the treated drinking water delivered to consumers by water purveyors. Relative-concentrations (sample concentrations divided by benchmark concentrations) were used for evaluating groundwater quality for those constituents that have Federal or California regulatory or non-regulatory benchmarks for drinking-water quality. A relative-concentration greater than 1.0 indicates a concentration greater than a benchmark. For organic (volatile organic compounds and pesticides) and special-interest (perchlorate) constituents, relative-concentrations were classified as high (greater than 1.0); moderate (equal to or less than 1.0 and greater than 0.1); or low (equal to or less than 0.1). For inorganic (major ion, trace element, nutrient, and radioactive) constituents, the boundary between low and moderate relative-concentrations was set at 0.5. Aquifer-scale proportions were used in the status assessment for evaluating regional-scale groundwater quality. High aquifer-scale proportion is defined as the percentage of the area of the primary aquifers that have a relative-concentration greater than 1.0 for a particular constituent or class of constituents; percentage is based on an areal rather than a volumetric basis. Moderate and low aquifer-scale proportions were defined as the percentage of the primary aquifers that have moderate and low relative-concentrations, respectively. Two statistical approaches—grid-based, which used one value per grid cell, and spatially-weighted, which used the full dataset—were used to calculate aquifer-scale proportions for individual constituents and classes of constituents. High and moderate aquifer-scale proportions were significantly greater for inorganic constituents than organic constituents in all three study units. In the Southern Sacramento Valley study unit, relative-concentrations for one or more inorganic constituents with health-based benchmarks (HBBs) were high in 30 percent (%), moderate in 30%, and low in 40% of the primary aquifer. In the Middle Sacramento Valley study unit, aquifer-scale proportions for inorganic constituents with HBBs were high in 24%, moderate in 38%, and low in 38% of the primary aquifer. Arsenic, boron, and nitrate were detected at high relative-concentrations in the Southern and Middle Sacramento Valley study units. In the Northern Sacramento Valley study unit, high, moderate, and low relative-concentrations of inorganic constituents relative to HBBs were 2.1, 12, and 86% of the primary aquifer, respectively. Arsenic was the only constituent detected at high relative-concentrations. The high aquifer-scale proportions for inorganic constituents with non-health-based benchmarks were 32, 27, and 4.6% of the primary aquifer for the Southern, Middle, and Northern Sacramento Valley study units, respectively. The high aquifer-scale proportions for organic constituents with HBBs were less than 1% in the Southern, Middle, and Northern Sacramento Valley study units. Organic constituents were detected at moderate relative-concentrations in about 3% of the Southern and Middle Sacramento Valley study units and in 1% of the Northern Sacramento Valley study unit. Of the 227 organic constituents analyzed for, 86 were detected, and of those detected, 56 have HBBs. Six organic constituents (atrazine, bentazon, chloroform, simazine, tetrachloroethene, and trichloroethene) were detected in 10% or more of the sampled wells in one or more of the three Sacramento Valley study units.

California↗

USGS2019

Pecos River Basin salinity assessment, Santa Rosa Lake, New Mexico, to the confluence of the Pecos River and the Rio Grande, Texas, 2015

The elevated salinity of the Pecos River throughout much of its length is of paramount concern to water users and water managers. Dissolved-solids concentrations in the Pecos River exceed 3,000 milligrams per liter in many of its reaches in the study area, from Santa Rosa Lake, New Mexico, to the confluence of the Pecos River with the Rio Grande, Texas. The salinity of the Pecos River increases downstream and affects the availability of useable water in the Pecos River Basin. In this report, “salinity” and “dissolved-solids concentration” are considered synonymous; both terms are used to refer to the total ionic concentration of dissolved minerals in water. The sources of salinity in the Pecos River Basin are natural (geologic) and anthropogenic, including but not limited to groundwater discharge, springs, and irrigation return flows. Previous studies in the Pecos River Basin were project specific and designed to address salinity issues in specific parts of the basin; therefore, in 2015, the U.S. Geological Survey in cooperation with the U.S. Army Corps of Engineers, New Mexico Interstate Stream Commission, Texas Commission on Environmental Quality, and Texas Water Development Board assessed the major sources of salinity throughout the extent of the basin where elevated salinity in the Pecos River is well documented (that is, in the drainage area of the Pecos River from Santa Rosa Lake to the confluence of the Pecos River and the Rio Grande). The goal was to gain a better understanding of how specific areas might be contributing to the elevated salinity in the Pecos River and how salinity of the Pecos River has changed over time. This assessment includes a literature review and compilation of previously published salinity-related data, which guided the collection of additional water-quality samples and streamflow gain-loss measurements. Differences in water quality of surface-water and groundwater samples, streamflow measurements, and geophysical data were assessed to gain new insights regarding sources of salinity in the Pecos River Basin and a more detailed assessment of potential areas of elevated salinity in the basin. The datasets compiled for this assessment are available in a companion data release. The literature review identified several potential sources of salinity inputs to the Pecos River in New Mexico and Texas. In New Mexico, sources of salinity inputs included sinkhole springs discharging into El Rito Creek, the Bitter Lake National Wildlife Refuge inflow to the Pecos River, inflow from the Rio Hondo, including the main channel and a restored channel at the Bitter Lake National Wildlife Refuge referred to as the “Rio Hondo spring channel,” the outflow from Lea Lake at Bottomless Lakes State Park, and the Malaga Bend region of the Pecos River. In Texas, sources of salinity inputs included Salt Creek downstream from Red Bluff Reservoir and the area near the Horsehead Crossing ford on the Pecos River. The compilation of historical water-quality data revealed a lack of consistent sampling of the same constituents at the same sites along the main stem of the Pecos River, which results in data gaps that hinder the ability to effectively analyze long-term changes in water quality that may help with the understanding of how salinity in the Pecos River has changed over time and identifying the sources of salinity in the Pecos River Basin. To help fill these data gaps, water-quality and streamflow data were collected in the study area in February 2015 by the U.S. Geological Survey. Historical water-quality data and newly collected data from February 2015 were evaluated for selected major-ion concentrations, dissolved-solids concentrations, and deuterium, oxygen, and strontium isotopes. Analysis of the data indicated several areas of increasing salinity in the Pecos River. Most notable increases were in two subreaches of the river, between Acme, N. Mex., and Artesia, N. Mex., and between Orla, Tex., and Grandfalls, Tex. Increasing sodium and chloride concentrations from Acme to Artesia coincided with changes in isotopic ratios within the Pecos River Basin. Changes in isotopic ratios in this reach indicate a likely inflow from an isotopically different source of water compared to the water in the main stem of the Pecos River, such as groundwater inflow, inflow from surface-water features distinct from the main stem of the Pecos River, or both. In the subreach between Orla and Grandfalls, an increase in dissolved-solids concentrations was observed along with a shift in isotope values, indicating that neither evaporative processes in Red Bluff Reservoir nor inflow from Salt Creek likely solely influences the salinity of the Pecos River in this subreach. The highest dissolved-solids concentrations in the Pecos River Basin were measured downstream from Grandfalls, where dissolved-solids concentrations are greater than 16,000 milligrams per liter near Iraan, Tex. Changes in isotopic values (deuterium, oxygen, and strontium) indicate mixing of different waters at several areas along the main stem of the Pecos River. The spatial distribution of the areas of interest from the literature review and the water-quality data are available in the companion data release.

Texas, New Mexico↗

USGS2015

Groundwater-level and storage-volume changes in the Equus Beds aquifer near Wichita, Kansas, predevelopment through January 2015

Development of the Wichita well field began in the 1940s in the Equus Beds aquifer to provide the city of Wichita, Kansas, a new water-supply source. After development of the Wichita well field began, groundwater levels began to decline. Extensive development of irrigation wells that began in the 1970s also contributed to substantial groundwater-level declines. Groundwater-level declines likely enhance movement of brine from past oil and gas production near Burrton, Kansas, and natural saline water from the Arkansas River into the Wichita well field. Groundwater levels reached a historical minimum in 1993 because of drought conditions, irrigation, and the city of Wichita’s withdrawals from the aquifer. In 1993, the city of Wichita adopted the Integrated Local Water Supply Program to ensure that Wichita’s water needs would be met through the year 2050 and beyond as part of its efforts to manage the part of the Equus Beds aquifer Wichita uses. A key component of the Integrated Local Water Supply Program was the Equus Beds Aquifer Storage and Recovery project. The Aquifer Storage and Recovery project’s goal is to store and eventually recover groundwater and help protect the Equus Beds aquifer from oil-field brine water near Burrton, Kansas, and saline water from the Arkansas River. Since 1940, the U.S. Geological Survey has monitored groundwater levels and storage-volume changes in the Equus Beds aquifer to provide data to the city of Wichita in order to better manage its water supply. Groundwater mostly flowed from west to east in the shallow and deep parts of the Equus Beds aquifer in January 2015. A large area of declines greater than 10 feet in the shallow part of the Equus Beds aquifer from predevelopment (before substantial pumpage began in the area in September 1940) to January 2015 covered most of the central part of the study area, where the city of Wichita well field is located, and extended beyond it. Groundwater-level rises of greater than 10 feet from 1993 (the historical minimum groundwater levels) to January 2015 covered most of the central part of the study area in the shallow and deep parts of the Equus Beds aquifer; rises of greater than 20 feet mostly were within the north-central part of the study area. The 1993 to January 2015 recovery of storage volume previously lost from predevelopment to 1993 was about 46 percent (55,200 acre-feet) for the central part of the study area and the percentage recovery was larger than the 31 percent (59,800 acre-feet) recovery for the entire study area. Groundwater-level rises and the larger percentage recovery of storage volume in the central part of the study area was most likely a result of the city of Wichita adopting the Integrated Local Water Supply Program strategy which reduced Wichita’s pumpage from the Equus Beds aquifer in 2014 to the smallest amount since 1940. January 2015 storage volumes were about 96 percent (3,057,000 acre-feet) and 94 percent (960,000 acre-feet) of total aquifer storage for the study area and the central part of the study area, respectively. Groundwater levels from January 2014 to January 2015 in the central part of the study area rose about 3 feet in some places, probably because Wichita reduced its withdrawals from the aquifer in 2014 by more than 50 percent. Groundwater levels probably recovered less than anticipated because of decreased recharge and net groundwater flow and increased agricultural pumpage. A volumetric water budget for the central part of the study area between 2013 and 2014 showed that the substantial decrease in total pumping (10,412 acre-feet) did not result in an increase in storage volume because it was more than offset by decreased recharge (6,502 acre-feet; artificial and from precipitation) and an even greater decrease in net groundwater flow (11,710 acre-feet).

Kansas↗

USGS2015

Water-quality trends in the Scituate reservoir drainage area, Rhode Island, 1983-2012

The Scituate Reservoir is the primary source of drinking water for more than 60 percent of the population of Rhode Island. Water-quality and streamflow data collected at 37 surface-water monitoring stations in the Scituate Reservoir drainage area, Rhode Island, from October 2001 through September 2012, water years (WYs) 2002-12, were analyzed to determine water-quality conditions and constituent loads in the drainage area. Trends in water quality, including physical properties and concentrations of constituents, were investigated for the same period and for a longer period from October 1982 through September 2012 (WYs 1983-2012). Water samples were collected and analyzed by the Providence Water Supply Board, the agency that manages the Scituate Reservoir. Streamflow data were collected by the U.S. Geological Survey. Median values and other summary statistics for pH, color, turbidity, alkalinity, chloride, nitrite, nitrate, total coliform bacteria, Escherichia coli ( E. coli ), and orthophosphate were calculated for WYs 2003-12 for all 37 monitoring stations. Instantaneous loads and yields (loads per unit area) of total coliform bacteria and E. coli , chloride, nitrite, nitrate, and orthophosphate were calculated for all sampling dates during WYs 2003-12 for 23 monitoring stations with streamflow data. Values of physical properties and concentrations of constituents were compared with State and Federal water-quality standards and guidelines and were related to streamflow, land-use characteristics, varying classes of timber operations, and impervious surface areas. Tributaries in the Scituate Reservoir drainage area for WYs 2003-12 were slightly acidic (median pH of all stations equal to 6.1) and contained low median concentrations of chloride (22 milligrams per liter [mg/L]), nitrate (0.01 mg/L as nitrogen), nitrite (0.001 mg/L as nitrogen), and orthophosphate (0.02 milligrams per liter as phosphorus [mg/L as P]). Turbidity and alkalinity values also were low with medians of 0.57 nephelometric turbidity units and 5.1 mg/L as calcium carbonate, respectively. Total coliform bacteria and E. coli were detected in most samples from all stations, but median concentrations were generally low-43 colony-forming units per 100 milliliters (mL) and 15 colony-forming units per 100 milliliters, respectively. Median values of several physical properties and median concentrations of several constituents correlated positively with the percentages of developed land and negatively with the percentages of forest cover in the drainage areas above the monitoring stations. Median concentrations of chloride correlated positively with the percentages of impervious land use in the subbasins of monitoring stations, likely reflecting the effects of deicing compounds applied to roadways during winter maintenance. Median concentrations of alkalinity also correlated positively with the percentage of impervious land use, which may be related to the deterioration of fabricated structures containing calcium carbonate. Median values of color correlated positively with the percentage of wetland area in the subbasins of monitoring stations, reflecting the natural sources of color in tributaries. Streamflows were negatively correlated with turbidity and concentrations of total coliform bacteria and E. coli, possibly reflecting seasonal patterns in which relatively high values of these properties and constituents occur during warmer low-flow conditions late in the water year. Similar seasonal patterns were observed for pH, alkalinity, and color. Negative correlations between concentrations of chloride and streamflow also were significant, indicating that deicing salts from roadways and other impervious surfaces that lack direct connection to the tributaries are likely infiltrating to the groundwater and discharging to some of the tributaries late in the water year. While salt-laden runoff directly enters some of the tributaries at roadway crossings, most of the roadway runoff infiltrates into the adjacent berms throughout the drainage area. Statistically significant correlations were not identified between various degrees of tree-canopy reduction caused by timber operations in the subbasins and median values or concentrations of water-quality properties. Loads and yields of chloride, nitrate, nitrite, orthophosphate, and bacteria varied at monitoring stations in the Scituate Reservoir drainage area in WYs 2003-12. Loads generally were greater at stations in the Barden Reservoir and the Regulating Reservoir Subbasins that have larger drainage areas than in subbasins with smaller drainage areas. Subbasin yields of fecal-indicator bacteria and orthophosphate generally were largest in the Westconnaug Reservoir Subbasin, and subbasin yields for chloride, nitrate, and nitrite were largest in the Moswansicut Reservoir Subbasin in the northeastern part of the drainage area. Upward trends in pH were identified for nearly half of the monitoring stations for WYs 1983-2012 and may reflect regional reductions in acid precipitation. Many upward trends in alkalinity also were identified for both the WYs 1983-2012 and for WYs 2003-12 periods and are likely related to the natural weathering of structures containing concrete or, in some cases, the application of lime or fertilizers on agriculture lands. Significant trends in chloride concentrations at most stations during WYs 1983-2012 were upward; however, results for WYs 2003-12 substantiate few significant upward trends and, in a few cases, downward trends were identified in several tributary drainage areas.

Rhode Island↗

USGS2004

Documentation of the Santa Clara Valley regional ground-water/surface-water flow model, Santa Clara Valley, California

The Santa Clara Valley is a long, narrow trough extending about 35 miles southeast from the southern end of San Francisco Bay where the regional alluvial-aquifer system has been a major source of water. Intensive agricultural and urban development throughout the 20th century and related ground-water development resulted in ground-water-level declines of more than 200 feet and land subsidence of as much as 12.7 feet between the early 1900s and the mid-1960s. Since the 1960s, Santa Clara Valley Water District has imported surface water to meet growing demands and reduce dependence on ground-water supplies. This importation of water has resulted in a sustained recovery of the ground-water flow system. To help support effective management of the ground-water resources, a regional ground-water/surface-water flow model was developed. This model simulates the flow of ground water and surface water, changes in ground-water storage, and related effects such as land subsidence. A numerical ground-water/surface-water flow model of the Santa Clara Valley subbasin of the Santa Clara Valley was developed as part of a cooperative investigation with the Santa Clara Valley Water District. The model better defines the geohydrologic framework of the regional flow system and better delineates the supply and demand components that affect the inflows to and outflows from the regional ground-water flow system. Development of the model includes revisions to the previous ground-water flow model that upgraded the temporal and spatial discretization, added source-specific inflows and outflows, simulated additional flow features such as land subsidence and multi-aquifer wellbore flow, and extended the period of simulation through September 1999. The transient-state model was calibrated to historical surface-water and ground-water data for the period 1970–99 and to historical subsidence for the period 1983–99. The regional ground-water flow system consists of multiple aquifers that are grouped into upper- and lower-aquifer systems. Ground-water inflow occurs as natural recharge in the form of streamflow infiltration and areal infiltration of precipitation along stream channels, artificial recharge from infiltration of imported water at recharge ponds and along selected stream channels, and leakage along selected transmission pipelines. Ground-water outflow occurs as evapotranspiration, stream base flow, discharge through pumpage from wells, and subsurface flow to the San Francisco Bay. The geohydrologic framework of the regional ground-water flow system was represented as six model layers. The hydraulic properties were redefined on the basis of cell-based lithologic properties that were delineated in terms of aggregate thicknesses of coarse-grained, fine-grained, and mixed textural categories. The regional aquifer systems also are dissected by several laterally extensive faults that may form at least partial barriers to the lateral flow of ground water. The spatial extent of the ground-water flow model was extended and refined to cover the entire Santa Clara Valley, including the Evergreen subregion. The temporal discretization was refined and the period of simulation was extended to 1970–99. The model was upgraded to MODFLOW-2000 (MF2K) and was calibrated to fit historical ground-water levels, streamflow, and land subsidence for the period 1970–99. The revised model slightly overestimates measured water levels with an root-mean-square error of -7.34 feet. The streamflow generally shows a good match on gaged creeks and rivers for flows greater than 1.2 cubic feet per second. The revised model also fits the measured deformation at the borehole extensometer site located near San Jose within 16 to 27 percent and the extensometer site near Sunnyvale within 3 percent of the maximum measured seasonal deformation for the deepest extensometers. The total ground-water inflow and outflow of about 225,500 acre-feet per year (acre-ft/yr) for the period 1970–89 and of about 205,300 acre-feet per year for the period for the period 1970–99 is comparable with that of the previous model, 207,200 acre-ft/yr for the period 1970–89. Overall the simulated net change in storage increased by about 189,500 acre-ft/yr for the entire period of simulation, which represents about one and a half years of the 1970–99 average pumping. The changes in ground-water flow and storage generally reflect the major climate cycles and the additional importation of water by Santa Clara Valley Water District, with the basin in recovery since the drought of the late 1980s and early 1990s. The average total recharge rate, from natural and artificial recharge and from streamflow infiltration for the revised model for the entire simulation period 1970–99, was about 157,100 acre-ft/yr, which represents about 59 percent of the inflow to the ground-water flow system. The average rate of artificial recharge of about 77,600 acre-ft/yr represents about 30 percent of the inflow to the ground-water flow system. The average pumpage for the entire 29.75-year simulation period is about 133,400 acre-ft/yr and represents about 69 percent of the outflow from the ground-water flow system. Most of the simulated recharge infiltrates and flows through the uppermost layers (i.e. model layers 1 and 3) of the aquifer system. Most of the water that flows to the deeper model layers is occurring through wellbores, with wellbore flow representing 19 percent of the total ground-water inflow between model layers.

California↗

USGS2014

Description of landscape features, summary of existing hydrologic data, and identification of data gaps for the Osage Nation, northeastern Oklahoma, 1890-2012

The Osage Nation of northeastern Oklahoma, conterminous with Osage County, is characterized by gently rolling uplands and incised stream valleys that have downcut into underlying sedimentary rock units of Pennsylvanian through Permian age. Cattle ranching and petroleum and natural-gas extraction are the principal land uses in this rural area. Freshwater resources in the Osage Nation include water flowing in the Arkansas River and several smaller streams, water stored in several lakes, and groundwater contained in unconsolidated alluvial aquifers and bedrock aquifers. The Vamoosa-Ada aquifer is the primary source of fresh groundwater in this area. Fresh groundwater is underlain by saline groundwater in aquifers underlying the Osage Nation. Because of the potential for future population increases, demands for water from neighboring areas such as the Tulsa metropolitan area, and expansion of petroleum and natural-gas extraction on water resources of this area, the U.S. Geological Survey, in cooperation with the Osage Nation, summarized existing hydrologic data and identified data gaps to provide information for planning of future development of water resources in the Osage Nation. Streamflows in the Osage Nation are substantially affected by precipitation. During the relatively wet periods from the 1970s to 2000, the annual streamflows in the Osage Nation increased by as much as a factor of 2 relative to preceding decades, with subsequent decreases in streamflow of as much as 50 percent being recorded during intermittent drier years of the early 2000s. This report summarizes hydrologic data from 3 surface-water sites and 91 wells distributed across the Osage Nation. Data collected at those sites indicate that surface water in the Osage Nation generally has sufficient dissolved oxygen for survival of both coldwater and warmwater aquatic biota. Total dissolved solids concentration exceeded the secondary drinking-water standard of 500 milligrams per liter (mg/L) in up to 75 percent of the surface-water samples, indicating limited availability of potable water at some sites. Some surface-water samples collected in the Osage Nation contained dissolved chloride concentrations exceeding the secondary drinking-water standard of 250 mg/L, with greater chloride concentrations in selected basins appearing to be associated with greater densities of petroleum well locations. Several lakes sampled in the Osage Nation from 2011–12 contained sufficient chlorophyll-a concentrations to be ranked as mesotrophic to eutrophic, indicating impairment by nutrients. Relatively large dissolved phosphorus concentrations in many surface-water samples, compared to water-quality standards, indicate that eutrophication can occur in local streams and lakes. The amount of fresh groundwater stored in alluvial aquifers and the Vamoosa-Ada bedrock aquifer is adequate for domestic and other purposes in the Osage Nation at the current rate of usage. In areas where these aquifers are absent, groundwater must be pumped from minor bedrock aquifers that produce smaller volumes of water. About 30 and 60 percent of 32 and 54 water samples collected from the alluvial and Vamoosa-Ada aquifers, respectively, contained total dissolved solids concentrations larger than the secondary drinking-water standard of 500 mg/L. Local factors, such as natural seepage of brines or leakage from petroleum and natural-gas extraction activities, may cause substantial variations in dissolved chloride concentration in groundwater in the Osage Nation. Total phosphorus concentrations measured in groundwater samples were similar to dissolved phosphorus concentrations measured in the base flow of several streams. Total fresh surface-water withdrawals (use) and fresh groundwater withdrawals in the Osage Nation were estimated to have increased from 0.75 to 16.19 million gallons per day and from 0.13 to 2.39 million gallons per day, respectively, over the period from 1890 through 2010. Estimated saline-groundwater reinjection volumes at the heavily developed Burbank Oil Field in the Osage Nation from 1950 through 2012 were many times larger than the total amounts of freshwater withdrawn in this area, with estimated increases in saline-groundwater reinjection in the 2000s probably being related to increased petroleum extraction. Estimates of freshwater resources in local streams, lakes, and freshwater aquifers and of net annual precipitation indicate that less than 1 percent of freshwater resources and net annual precipitation currently is being withdrawn annually in the Osage Nation. In addition to freshwater resources, the Osage Nation may be underlain by 45,000,000 million gallons of brines, a small portion of which are withdrawn and reinjected during petroleum and natural-gas extraction. Ongoing development of desalinization technology may lead to the ability to expand use of these saline waters in the future. Several additional studies could improve understanding of the hydrologic resources of the Osage Nation. Development of computer models (simulations) of groundwater and surface-water flow for this area could enable testing of scenarios of localized and widespread effects of future climate variations and water-use changes on streamflows, lake-water levels, and groundwater levels in the Osage Nation. Installation of additional long-term streamflow and water-quality sampling stations, some with continuous water-quality monitors, could expand and improve understanding of surface-water quality. Periodic measurement of groundwater levels and sampling of water from a network of wells could provide better information about trends of groundwater quantity and quality with time. Measurement of water withdrawals at selected sites could enable more accurate estimates of water use. Lastly, better understanding of aquifer properties and spatial distribution of saline groundwater provided by geophysical surveys could improve understanding of fresh and saline groundwater resources underlying the Osage Nation.

Oklahoma↗

USGS2017

The effects of forest cover on base flow of streams in the mountainous interior of Puerto Rico, 2010

The U.S. Geological Survey, in cooperation with the Puerto Rico Department of Natural and Environmental Resources, completed a study to determine whether a relation exists between the extent of forest cover and the magnitude of base flow at two sets of paired drainage basins in the highlands of the municipalities of Adjuntas and Utuado within the mountainous interior of Puerto Rico. One set of paired basins includes the Río Guaónica and Río Tanamá, both tributaries of the Río Grande de Arecibo. The other set includes two smaller basins in the drainage basin of the Río Coabey, which is a tributary of the Río Tanamá. The paired basins in each set have similar rainfall patterns, geologic substrate, and aspect; the principal difference identified in the study is the extent of forest cover and related land uses such as the cultivation of shade and sun coffee. Data describing the hydrology, hydrogeology, and streamflow were used in the analysis. The principal objective of the study was to compare base flow per unit area among basins having different areal extents of forest cover and land uses such as shade coffee and sun coffee cultivation. Within the mountainous interior of Puerto Rico, a substantial amount of the annual rainfall (45 to 39 percent in the Rio Guaónica and Rio Tanamá, respectively) can migrate to the subsurface and later emerge as base flow in streams. The magnitude of base flow within the two sets of paired basins varies seasonally. Minimum base flows occur during the annual dry season (generally from January to March), and maximum base flows occur during the wet season (generally from August to October). During the dry season or periods of below-normal rainfall, base flow is either the primary or the sole component of streamflow. Daily mean base flow ranged from 3.2 to 20.5 cubic feet per second (ft3 /s) at the Rio Guaónica Basin, and from 4.2 to 23.0 ft3 /s at the Rio Tanamá Basin. The daily mean base flows during 2010 ranged from 0.28 to 0.98 ft3 /s at Tributary 1 and from 0.22 to 0.58 ft3 /s at Tributary 2 of the Rio Coabey. The normalized daily base flow at the Río Guaónica and Río Tanamá Basin during 2010 ranged from 1.3 to 8.1 cubic feet per second per square mile (ft3 /s)/mi2 and from 1.1 to 6.1 (ft3 /s)/mi2 , respectively. The normalized daily base flow for the basins of Tributary 1 and Tributary 2 of Río Coabey during 2010 ranged from 1.0 to 3.6 (ft3 /s)/mi2 and from 1.5 to 3.9 (ft3 /s)/mi2 , respectively. The normalized mean annual base flow is similar within the larger paired basins of Río Tanamá (2.74 [ft3 /s]/mi2 ) and Río Guaónica (3.15 [ft3 /s]/mi2 ). The mean annual base flow per unit area for both of these basins is about 79 percent of the mean annual streamflow. In the large paired basins, the proportion of Type I land use (forest patches, shade and mixed shade/sun coffee with associated cash crops) is substantially higher in Rio Guaónica Basin (81 percent) than in the Rio Tanamá Basin (59 percent), and the base flow per unit area is also higher. In the small paired basins of Rio Coabey, the proportion of Type I land use is much higher at Tributary 1 (52 percent) than at Tributary 2 (15 percent), but, in contrast to the large basins, the mean annual base flow per unit area is lower (2.22 and 2.62 [ft3 /s]/mi2 , respectively). There is no consistent relation between land use and normalized base flow between the two sets of paired basins in the study.

Scientific Investigations Report↗

USGS2008

Quantifying Ground-Water and Surface-Water Discharge from Evapotranspiration Processes in 12 Hydrographic Areas of the Colorado Regional Ground-Water Flow System, Nevada, Utah, and Arizona

Rapid population growth in southern Nevada has increased the demand for additional water supplies from rural areas of northern Clark and southern Lincoln counties to meet projected water-supply needs. Springs and rivers in these undeveloped areas sustain fragile riparian habitat and may be susceptible to ground-water withdrawals. Most natural ground-water and surface-water discharge from these basins occurs by evapotranspiration (ET) along narrow riparian corridors that encompassed about 45,000 acres or about 1 percent of the study area. This report presents estimates of ground- and surface-water discharge from ET across 3.5 million acres in 12 hydrographic areas of the Colorado Regional Ground-Water Flow System. Ground-and surface-water discharge from ET were determined by identifying areas of ground- and surface-water ET, delineating areas of similar vegetation and soil conditions (ET units), and computing ET rates for each of these ET units. Eight ET units were identified using spectral-reflectance characteristics determined from 2003 satellite imagery, high-resolution aerial photography, and land classification cover. These ET units are dense meadowland vegetation (200 acres), dense woodland vegetation (7,200 acres), moderate woodland vegetation (6,100 acres), dense shrubland vegetation (5,800 acres), moderate shrubland vegetation (22,600 acres), agricultural fields (3,100 acres), non-phreatophytic areas (3,400,000 acres), and open water (300 acres). ET from diffuse ground-water and channelized surface-water is expressed as ETgs and is equal to the difference between total annual ET and precipitation. Total annual ET rates were calculated by the Bowen ratio and eddy covariance methods using micrometeorological data collected from four sites and estimated at 3.9 ft at a dense woodland site (February 2003 to March 2005), 3.6 ft at a moderate woodland site (July 2003 to October 2006), 2.8 ft at a dense shrubland site (June 2005 to October 2006), and 1.5 ft at a moderate shrubland site (April 2006 to October 2006). Annual ETgs rates were 3.4 ft for dense woodland vegetation, 3.2 ft for moderate woodland vegetation, 2.2 ft for dense shrubland vegetation, and 1.0 ft for moderate shrubland vegetation. Published annual rates of ETgs were used for the other ET units found in the study area. These rates were 3.4 ft for dense meadowland vegetation, 5.2 ft for agricultural fields, and 4.9 ft for open water. For the non-phreatophytic ET unit, ETgs was assumed to be zero. Estimated ground- and surface-water discharge from ET was calculated by multiplying the ETgs by the ET-unit acreage and equaled 24,480 acre-ft for dense woodland vegetation, 19,520 acre-ft for moderate woodland vegetation, 12,760 acre-ft for dense shrubland vegetation, 22,600 acre-ft for moderate shrubland vegetation, 680 acre-ft for dense meadowland vegetation, 16,120 acre-ft for agricultural fields, 1,440 acre-ft for open water, and 0 acre-ft for the non-phreatophytic ET unit. Estimated ground-water and surface-water discharge from ET from each hydrographic area was calculated by summing the total annual ETgs rate for ET units found within each hydrographic area and equaled 1,952 acre-ft for the Black Mountains Area, 6,080 acre-ft for California Wash, 4,090 acre-ft for the Muddy River Springs Area, 11,510 acre-ft for Lower Moapa Valley, 51,960 acre-ft for the Virgin River Valley, 16,168 acre-ft for Lower Meadow Valley Wash, 5,840 acre-ft for Clover Valley, and 0 acre-ft for Coyote Spring Valley, Kane Springs Valley, Tule Desert, Hidden Valley (North), and Garnet Valley. The annual discharge from ETgs for the study area totals about 98,000 acre-ft.

Scientific Investigations Report↗

USGS2024

Analysis of water use associated with hydraulic fracturing and determination of baseline water quality in watersheds within the shale play of eastern Ohio, 2021–23

The U.S. Geological Survey, in cooperation with the Ohio Department of Natural Resources, performed a two-part study to (1) assess water use and temporal trends and changes in streamflow, and to (2) characterize 2021–23 baseline water quality, as they relate to oil and gas extraction activities in selected eastern Ohio watersheds. Between calendar years 2010 and 2019, hydraulic fracturing water withdrawals totaling about 27,168 million gallons were reported at 643 locations in Ohio. In 2021, wells developed with hydraulic fracturing were the source of most of the oil and gas produced in Ohio. Daily streamflow time-series data from seven study gages and two reference gages were used to assess temporal trends and changes in streamflow. The study gages were in basins with reported water withdrawals for hydraulic fracturing. The reference gages, which have long periods of record and were subject to minimal streamflow regulation, were in nearby basins with no hydraulic fracturing water withdrawals. Trend slopes for the period of record annual minimum and median daily streamflows and for annual daily streamflow nonexceedance probabilities less than 0.9 were all uniformly positive at the study and reference gages. This trend indicates a consistently increasing pattern over the periods of record, except for high flows. In addition, analyses of annual streamflow statistics showed no general indication that low flows or extreme low flows at the reference or study gages have lowered, become more frequent, or lengthened in duration since 2010, when records for hydraulic fracturing water withdrawals began in Ohio. In fact, in almost all cases, the opposite was indicated. Nonexceedance percentiles of daily streamflows were compared between the full and pre-2012 periods of record for reference and study gages. The streamflows associated with nonexceedance percentiles in the lower quartile of daily streamflows determined for the full period of record were larger than or equal to those determined for the pre-2012 period of record for all study and reference gages. This indicates that low flows did not decrease during the post-2011 period of record when water was withdrawn for hydraulic fracturing. Water-quality data were collected eight times at each of eight sampling sites (six of which were colocated with the study gages). Sampling was done during a variety of flow conditions to assess baseline water quality. In 2021, the 8 sampling sites had drainage basins that were wholly or partially within 7 of the 10 most active counties in Ohio for oil and gas development. As part of the record of baseline conditions, water-quality data were used to assess (1) water types based on major-ion chemistry; (2) sources of salinity to streams; (3) exceedances of aquatic life use criteria; and (4) the correlations between water chemistry and drainage-basin characteristics, such as density of oil and gas wells, density of wastewater treatment plants, or the percentage of different types of land cover (agriculture, developed, forest). Seven of the water-quality sampling sites were designated as coal-mine impacted based on criteria developed for assessing mine-drainage impacts in Ohio. Mine drainage from historical coal mining in the region likely affected the quality of these streams and complicated the use of some constituents typically used as indicators of oil and gas influence. Based on major-ion chemistry, three main types of water were in the study area―sulfate (three sites), calcium-bicarbonate (one site), and mixed bicarbonate-chloride (four sites) type waters. One site had samples with a higher proportion of sodium and chloride ions than other stream samples, indicating potential contamination with oil-field brine or road salt. Binary mixing curves revealed that 11 samples from 4 of the sampling sites likely contained a component of brine. The results of the baseline assessment of surface-water quality in the study area showed no exceedances of Ohio Environmental Protection Agency aquatic life use criteria. Spearman’s rank correlation coefficients indicated no significant positive correlations with the density of vertical or horizontal oil and gas wells.

Ohio↗