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USGS2003

Water-quality trend analysis and sampling design for streams in North Dakota, 1971-2000

This report presents the results of a study conducted by the U.S. Geological Survey, in cooperation with the North Dakota Department of Health, to analyze historical water-quality trends in selected dissolved major ions, nutrients, and dissolved trace metals for 10 streams in southwestern and eastern North Dakota and to develop an efficient sampling design to monitor future water-quality trends. A time-series model for daily streamflow and constituent concentration was used to identify significant concentration trends, separate natural hydroclimatic variability in concentration from variability that could have resulted from anthropogenic causes, and evaluate various sampling designs to monitor future water-quality trends. The interannual variability in concentration as a result of variability in streamflow, referred to as the annual concentration anomaly, generally was high for all constituents and streams used in the trend analysis and was particularly sensitive to the severe drought that occurred in the late 1980's and the very wet period that began in 1993 and has persisted to the present (2002). Although climatic conditions were similar across North Dakota during the trend-analysis period (1971-2000), significant differences occurred in the annual concentration anomalies from constituent to constituent and location to location, especially during the drought and the wet period. Numerous trends were detected in the historical constituent concentrations after the annual concentration anomalies were removed. The trends within each of the constituent groups (major ions, nutrients, and trace metals) showed general agreement among the streams. For most locations, the largest dissolved major-ion concentrations occurred during the late 1970's and concentrations in the mid- to late 1990's were smaller than concentrations during the late 1970's. However, the largest concentrations for three of the Missouri River tributaries and one of the Red River of the North tributaries occurred during the mid- to late 1990's. Concentration trends for total ammonia plus organic nitrogen showed close agreement among the streams for which that constituent was evaluated. The largest concentrations occurred during the early 1980's, and the smallest concentrations occurred during the early 1990's. Nutrient data were not available for the early 1970's or late 1990's. Although a detailed analysis of the causes of the trends was beyond the scope of this report, a preliminary analysis of cropland, livestock-inventory, and oil-production data for 1971-2000 indicated the concentration trends may be related to the livestock-inventory and oil-production activities in the basins. Dissolved iron and manganese concentrations for the southwestern North Dakota streams generally remained stable during 1971-2000. However, many of the recorded concentrations for those streams were less than the detection limit, and trends that were masked by censoring may have occurred. Several significant trends were detected in dissolved iron and manganese concentrations for the eastern North Dakota streams. Concentrations for those streams either remained stable or increased during most of the 1970's and then decreased rapidly for about 2 years beginning in the late 1970's. The concentrations were relatively stable from the early 1980's to 2000 except at two locations where dissolved iron concentrations increased during the early 1990's. The most efficient overall sampling designs for the detection of annual trends (that is, trends that occur uniformly during the entire year) consisted of balanced designs in which the sampling dates and the number of samples collected remained fixed from year to year and in which the samples were collected throughout the year rather than in a short timespan. The best overall design for the detection of annual trends consisted of three samples per year, with samples collected near the beginning of December, April, and August. That design had acceptable sensitivity for the detection of trends in most constituents at all locations. Little improvement in sensitivity was achieved by collecting more than three samples per year. The sampling designs that were first evaluated for annual trends also were evaluated with regard to their sensitivity to detect seasonal trends that occurred during three seasons--April through August, August through December, and December through April. Design results indicated that an average of one extra sample per station per year resulted in an efficient design for detecting seasonal trends. However, allocation of the extra samples varied depending on the station, month, and constituent group (major ions, nutrients, and trace metals).

North Dakota↗

USGS1997

Effects of urbanization on water quality in the Kansas River, Shunganunga Creek Basin, and Soldier Creek, Topeka, Kansas, October 1993 through September 1995

A study of urban-related water-qulity effects in the Kansas River, Shunganunga Creek Basin, and Soldier Creek in Topeka, Kansas, was conducted from October 1993 through September 1995. The purpose of this report is to assess the effects of urbanization on instream concentrations of selected physical and chemical constituents within the city of Topeka. A network of seven sampling sites was established in the study area. Samples principally were collected at monthly intervals from the Kansas River and from the Shunganunga Creek Basin, and at quarterly intervals from Soldier Creek. The effects of urbanization werestatistically evaluated from differences in constituent concentrations between sites on the same stream. No significant differences in median concentrations of dissolved solids, nutrients, or metals and trace elements, or median densities offecal bacteria were documented between sampling sites upstream and downstream from the major urbanized length of the Kansas River in Topeka.Discharge from the city's primary wastewater- treatment plant is the largest potential source of contamination to the Kansas River. This discharge increased concentrations of dissolved ammonia, totalphosphorus, and densities of fecal bacteria.Calculated dissolved ammonia as nitrogen concentrations in water from the Kansas River ranged from 0.03 to 1.1 milligrams per liter after receiving treatment-plant discharge. However, most of the calculated concentrations wereconsiderably less than 50 percent of Kansas Department of Health and Environment water- quality criteria, with a median value of 20 percent.Generally, treatment-plant discharge increased calculated total phosphorus concentrations in water from the Kansas River by 0.01 to 0.04 milligrams per liter, with a median percentage increase of 7.6 percent. The calculated median densities of fecal coliform and fecal Streptococci bacteria in water from the Kansas River increased from 120 and 150colonies per 100 milliliters of water, respectively, before treatment-plant discharge to a calculated 4,900 and 4,700 colonies per 100 milliliters of water, respectively, after discharge. Median concentrations of dissolved solids were not significantly different between three sampling sites in the Shunganunga Creek Basin. Median concentrations of dissolved nitrate as nitrogen, total phosphorus, and dissolved orthophosphate were significantly larger in water from the upstream- most Shunganunga Creek sampling site than in water from either of the other sampling sites in the Shunganunga Creek Basin probably because of the site's proximity to a wastewater-treatment plant.Median concentrations of dissolved nitrate as nitrogen and total phosphorus during 1993-95 at upstream sampling sites were either significantlylarger than during 1979-81 in response to increase of wastewater-treatment plant discharge or smaller because of the elimination of wastewater-treatment plant discharge. Median concentrations of dissolved ammonia as nitrogen were significantly less during 1993-95 than during 1979-81. Median concentrations of total aluminum, iron, maganese, and molybdenum were significantly larger in water from the downstream-mostShunganunga Creek sampling site than in water from the upstream-most sampling site. This probably reflects their widespread use in the urbanenvironment between the upstream and downstream Shunganunga Creek sampling sites. Little water-quality effect from the urbanization was indicated by results from the Soldier Creek sampling site. Median concentrations of most water-quality constituents in water from this sampling site were the smallest in water from any sampling site in the study area. Herbicides were detected in water from all sampling sites. Some of the more frequently detected herbicides included acetochlor, alachlor,atrazine, cyanazine, EPTC, metolachlor, prometon, simazine, and tebuthiuron. Detected insecticides including chlordane,

Water-Resources Investigations Report↗

USGS1998

Surface-water quality at fixed sites in the Western Lake Michigan Drainages, Wisconsin and Michigan, and the effects of natural and human factors, 1993-95

Streamwater samples were collected from April 1993 through July 1995 at 11 fixed sites in the Western Lake Michigan Drainages Study Unit of the U.S. Geological Survey's National Water-Quality Assessment Program. Water samples were collected monthly at all Fixed Sites, and an additional two to four samples were collected each year during periods of high flow. Streamflow was monitored continuously at the Fixed Sites for the duration of the study period. This report describes field techniques used to collect the water samples, and the analytical methods used for laboratory analyses, statistical analyses of the data, and an attempt to determine the effect of natural and anthropogenic factors on concentrations of nutrients and selected major ions and suspended solids. Locations of eight of the Fixed Sites were selected to represent areas with unique combinations of land use/land cover, surficial deposits, and bedrock geology and are referred to as 'indicator sites.' The remaining three sites were located near the mouths of major rivers and are referred to as 'integrator sites.' The integrator sites represent a large part of the total flow from the Study Unit to Green Bay and western Lake Michigan, and drain various combinations of land use, bedrock, and surficial deposits. These data indicate that land use and surficial deposits may be the primary factors affecting nitrate and total phosphorus concentrations in this Study Unit. Median concentrations of nitrate at the forested sites were less than the National Median Concentration (NMC), and those at urban fixed sites were similar to the NMC. Median nitrate concentrations at the Tomorrow River, North Branch Milwaukee River, and Duck Creek agricultural indicator sites were twice the NMC, but median concentrations at the remaining agricultural indicator sites were similar to the NMC. Nitrate concentrations at one agricultural indicator site exceeded the U. S. Environmental Protection Agency (USEPA) maximum contaminant level in three run-off samples in the growing seasons of 1994 and 1995. Median concentrations of total phosphorus at the forested indicator sites were below the NMC. Tomorrow River was the only agricultural indicator site where the median total-phosphorus concentration was less than the NMC; median concentrations at the remaining agricultural Fixed Sites were similar to the NMC and exceeded 0.1 mg/L, the USEPA suggested total-phosphorus concentration in flowing water. The USEPA recommends that total-phosphorus concentration not exceed this limit to discourage excessive aquatic plant growth in flowing waters. Median total-phosphorus concentration at the urban indicator site was less than the urban NMC. Median concentrations for both nitrate and total phosphorus at the mouth of the Fox River and the Milwaukee River integrator sites were similar to the NMC for the dominant land use, agriculture, within their basins, and were lower than that at the Menominee River integrator site with a dominant forest land use. During this study, potassium concentrations were generally highest in areas of clay-dominated surficial deposits, silica was generally highest in areas of sandy surficial deposits, iron generally highest in areas of igneous/metamorphic bedrock, and calcium generally highest in areas of carbonate bedrock. The highest median fluoride concentration occurred at an urban site that receives treated water.

Michigan, Wisconsin↗

USGS2000

Hydrogeology and simulation of ground-water flow at Dover Air Force Base, Delaware

Dover Air Force Base in Kent County, Delaware, has many contaminated sites that are in active remediation. To assist in this remediation, a steady-state model of ground-water flow was developed to aid in understanding the hydrology of the system, and for use as a ground-watermanagement tool. This report describes the hydrology on which the model is based, a description of the model itself, and some applications of the model.Dover Air Force Base is underlain by unconsolidated sediments of the Atlantic Coastal Plain. The primary units that were investigated include the upper Calvert Formation and the overlying Columbia Formation. The uppermost sand unit in the Calvert Formation at Dover Air Force Base is the Frederica aquifer, which is the deepest unit investigated in this report. A confining unit of clayey silt in the upper Calvert Formation separates the Frederica aquifer from the lower surficial aquifer, which is the basal Columbia Formation. North and northwest of Dover Air Force Base, the Frederica aquifer subcrops beneath the Columbia Formation and the upper Calvert Formation confining unit is absent. The Calvert Formation dips to the southeast. The Columbia Formation consists predominately of sands, silts, and gravels, although in places there are clay layers that separate the surficial aquifer into an upper and lower surficial aquifer. The areal extent of these clay layers has been mapped by use of gamma logs. Long-term hydrographs reveal substantial changes in both seasonal and annual ground-water recharge. These variations in recharge are related to temporal changes in evaporation, transpiration, and precipitation. The hydrographs show areas where extensive silts and clays are present in the surficial aquifer. In these areas, the vertical gradient between water levels in wells screened above and below the clays can be as large as several feet, and local ground-water highs typically form during normal recharge conditions. When drought conditions persist, water drains off these highs and the vertical gradients decrease. At the south end of Dover Air Force Base, hydrographs of water levels in the Frederica aquifer show that off-Base pumping can cause the water levels to decline below sea level during part of the year.A 4-layer, steady-state numerical model of ground-water flow was developed for Dover Air Force Base and the surrounding area. The upper two layers represent the upper and lower surficial aquifers, which are in the Columbia Formation. In some areas of the model, a semi-confining unit is used to represent an intermittent clay layer between the upper and lower surficial aquifer. This semi-confining unit causes the local groundwater highs in the surficial aquifer. The third model layer represents the upper part of the Calvert Formation, a confining unit. The fourth model layer represents the Frederica aquifer. The model was calibrated to hydraulic heads and to ground-water discharge in Pipe Elm Branch, both of which were measured in September 1997. For the calibrated model, the root-mean-squared errors for the hydraulic heads and the ground-water discharge in the Pipe Elm Branch were 9 percent of the range of head and 3 percent of discharge, respectively. Heads simulated by use of the model were consistent with a map showing average water levels in the region. The U.S. Geological Survey?s MODPATH program was used to simulate ground-water-flow directions for several areas on the Base. This analysis showed the effects of the local groundwater highs. In these areas, ground water can flow from the highs and then dramatically change flow direction as it enters the lower surficial aquifer. The steady-state model has several limitations. The entire ground-water system is under transient hydraulic conditions, due mainly to seasonal and yearly changes in recharge and to withdrawal from irrigation wells. Yet this steady-state model is still considered to be an effective tool for understanding the ground-water-flow system u

Water-Resources Investigations Report↗

USGS1999

An assessment of stream habitat and nutrients in the Elwha River basin: implications for restoration

The Elwha River was once famous for its 10 runs of anadromous salmon which included chinook that reportedly exceeded 45 kilograms. These runs either ceased to exist or were significantly depleted after the construction of the Elwha (1912) and Glines Canyon (1927) Dams, which resulted in the blockage of more than 113 kilometers of mainstem river and tributary habitat. In 1992, in response to the loss of the salmon runs in the Elwha River Basin, President George Bush signed the Elwha River Ecosystem and Fisheries Restoration Act, which authorizes the Secretary of the Interior to remove both dams for ecosystem restoration. The objective of this U.S. Geological Survey (USGS) study was to begin describing baseline conditions for assessing changes that will result from restoration. The first step was to review available physical, chemical, and biological information on the Elwha River Basin. We found that most studies have focused on anadromous fish and habitat and that little information is available on water quality, habitat classification, geomorphic processes, and riparian and aquatic biological communities. There is also a lack of sufficient data on baseline conditions for assessing future changes if restoration occurs. The second component of this study was to collect water-quality and habitat data, filling information gaps. This information will permit a better understanding of the relation between physical habitat and nutrient conditions and changes that may result from salmon restoration. We collected data in the fall of 1997 and found that the concentrations of nitrogen and phosphorous were generally low, with most samples having concentrations below detection limits. Detectable concentrations of nitrogen were associated with sites in the lower reach of the Elwha River, whereas the few detections of phosphorus were at sites throughout the basin. Nutrient data indicate that the Elwha River and its tributaries are oligotrophic. Results of the stream classification indicated that most of the habitat that would be usable by salmon is found in the mainstem of the Elwha River due to natural gradient barriers at the lower end of most tributaries. Habitat is diverse in the mainstem due to large woody debris accumulations and the existence of secondary channels. We concluded that restoring salmon runs to the Elwha River system will affect the ecosystem profoundly. Decaying carcasses of migrating salmon will be the source of large quantities of nutrients to the Elwha River. The complex instream habitat of the mainstem will enhance cycling of these nutrients because carcasses will be retained long enough to be assimilated thereby increasing primary and secondary production, size of immature salmonids, and overall higher salmon recruitment.

Washington↗

USGS2001

Ground-water flow to Death Valley, as inferred from the chemistry and geohydrology of selected springs in Death Valley National Park, California and Nevada

Death Valley lies downgradient from adjacent valleys to the north, south, east, and west in California and Nevada, and is the site of substantial ground-water discharge. The sources of the discharging waters have been discussed by several investigators in the past and are of heightened concern because of the potential disposal of high-level radioactive waste at Yucca Mountain, Nevada, and because of ground-water withdrawals attendant to commercial mining in the northwestern Amargosa Valley region. This report describes high- and low-discharge springs in and along the Amargosa Range that were sampled to augment the level of understanding of the extent and distribution of westward ground-water flow through the range. The Black Mountains do not seem to be part of a significant path of ground-water flow from the Amargosa region. This is attributed to the complex lithology and geologic history of the Black Mountains structural block and to the presence of the intervening Furnace Creek fault zone. The only ground-water discharge associated with the Black Mountains where water chemistry reflects an external source or sources is Saratoga Spring, for which δ 2 H and δ 18 O data indicate recharge in the Spring Mountains to the east. The southern part of the Funeral Mountains transmits a large volume of water through faulted and fractured rocks of Cambrian age that lie at or along the distal part of the northeast -oriented Spotted Range-Mine Mountain structural zone. Waters discharging from springs in the Furnace Creek Ranch vicinity (Travertine and Nevares) both compositionally and isotopically resemble waters from the Ash Meadows spring group in the Amargosa Desert. The Ash Meadows springs and water in the Amargosa Valley alluvium likely are chemically representative of ground water entering the southern Funeral Mountains. Much less ground water flows through the central and northern Funeral Mountains than flows through the southern part, as indicated by the geologic setting and chemistry of Keane Wonder Spring. The northern one-half of the mountains comprises early-to-middle Proterozoic metamorphic rocks that are the core of the Funeral Mountains anticlinorium. The core is largely unfaulted, plunges to the northeast and southwest, and is truncated to some extent on the east by the shallow-dipping Boundary Canyon fault. This structural setting and the paucity of springs in the northern one-half of the Funeral Mountains indicate a long traveltime from the Amargosa region to the western margin of the northern and central parts of the mountains. The Grapevine Mountains include the highest elevations in the Amargosa Range. Substantial precipitation and recharge above about 2,000 meters are evinced by numerous small springs and seeps along the east and west margins. The local nature of the recharge is reflected in δ 2 H and δ 18 O values and in the spring chemistries that indicate control by Tertiary volcanic rocks. The highest spring discharges associated with the Grapevine Mountains are near the north end of the mountains in the Grapevine Ranch area. The springs in this area are similar chemically and isotopically, except for one or two order-of-magnitude differences in calcium, magnesium, and strontium concentrations and a 1.2 per mil difference in δ 13 C values. These differences can be attributed to differences in the distal parts of the respective flow paths. The springs also lie at the end of a northeast -oriented structural zone in the Walker Lane Belt, and their δ 2 H, δ 13 C, and δ 18 O values indicate a recharge area likely to the northeast, outside of the Grapevine Mountains.

California;Nevada↗

USGS1997

Nitrate in ground water and stream base flow in the lower Susquehanna River Basin, Pennsylvania and Maryland

High concentrations of nitrate in both ground and surface water have been identified as a significant water-quality issue in the Lower Susquehanna River Basin. This report uses data collected by the National Water Quality Assessment (NAWQA) Program in the basin and compares nitrate concentrations found in ground water and surface water on both a spatial and temporal basis and relates nitrate concentrations to land use. Nitrate concentrations in the Lower Susquehanna River Basin in Pennsylvania and Maryland were higher in ground water than in surface water in agricultural areas underlain by carbonate bedrock and agricultural areas underlain by crystalline bedrock. Nitrate concentrations were higher in surface water than in ground water in urban areas underlain by carbonate bedrock. Nitrate concentrations also were higher in surface water than ground water in both agricultural and forested areas underlain by sandstone and shale. Nitrate concentrations in ground water vary in areas with different land use and bedrock type. Ground-water nitrate concentrations were highest in agricultural areas underlain by carbonate bedrock, where 45 percent of the samples exceeded the U.S. Environmental Protection Agency (USEPA) Maximum Contaminant Level (MCL) of 10 mg/L (milligrams per liter as N). Waters from 36 percent of the wells in agricultural areas underlain by crystalline bedrock also had nitrate concentrations greater than 10 mg/L. Nitrate concentrations in water from wells in urban areas underlain by carbonate bedrock and in forested and agricultural areas underlain by sandstone and shale seldom exceeded the MCL. Nitrate concentrations were generally higher in surface water in areas underlain by carbonate bedrock than in areas underlain by noncarbonate bedrock; however, when an agricultural area underlain by carbonate bedrock and an agricultural area underlain by sandstone and shale with similar manure application rates were compared, nitrate concentrations in surface water were not significantly different. A comparison of three agricultural areas underlain by carbonate bedrock shows that the manure application rate is strongly correlated with nitrate concentration. Nitrate concentrations in stream base flow at seven sites where samples were collected throughout the year were commonly higher in the winter months than in the summer months. A statistically significant correlation between streamflow and nitrate concentration existed for six of the seven sites, indicating that seasonal variability in precipitation may be the cause of some of the seasonal variation in concentration. Other possible explanations for this variation include the seasonal cycle in plant uptake of nitrogen and seasonal fluctuations in uptake of nitrate by algae in streams. Because no information was available about the traveltime for ground water, interpretation of this temporal variation was not conclusive. Estimates of base-flow loads and yields of nitrate showed that agricultural areas underlain by carbonate bedrock provide the highest yield of nitrate when compared with the other areas studied. Agricultural areas underlain by sandstone and shale and crystalline bedrock also provide large amounts of nitrate to the river. The large amount of nitrate in the water from these areas cause a significant increase in nitrate loads transported by the Susquehanna River to the Chesapeake Bay. Urban areas underlain by carbonate bedrock had a high yield of nitrate but comprise such a small part of the basin that the nitrate load from these areas was small. In contrast, forested areas underlain by sandstone and shale bedrock had low base-flow nitrate yields, but these areas comprise a large percentage of the basin, making the overall nitrate load from these areas high.

Maryland, Pennsylvania↗

USGS2002

Pesticides in surface water of the Yakima River basin, Washington, 1999–2000 — Their occurrence and an assessment of factors affecting concentrations and loads

The occurrence, distribution, and transport of pesticides in surface water of the Yakima River Basin were assessed using data collected during 19992000 as part of the U.S. Geological Survey National Water-Quality Assessment (NAWQA) Program. Samples were collected at 34 sites located throughout the basin in August 1999 using a Lagrangian sampling design. Samples also were collected weekly and monthly from May 1999 through January 2000 at three of the sites. This report includes data for 47 pesticide compounds from the analysis of filtered water using ocadecyl (C-18) solid-phase extraction and gas chromatography/mass spectrometry. Twenty-five pesticide compounds were detected in samples collected during the study. Detection frequencies ranged from about 1 percent for ethalfluralin, ethoprophos, and lindane to 82 percent for atrazine. Maximum concentrations of azinphos-methyl, carbaryl, diazinon, para,para'-dichlorodiphenyldichloroethylene (p,p'-DDE), and lindane exceeded chronic-toxicity guidelines for the protection of freshwater aquatic life. Twenty pesticide compounds were detected during sampling in August 1999. Atrazine was the most widely detected herbicide, and azinphos-methyl was the most widely detected insecticide. The median number of sites at which a particular pesticide compound was detected was six. Pesticide compounds detected at more than six sites include atrazine, simazine, terbacil, trifluralin, deethylatrazine, azinphos-methyl, carbaryl, diazinon, malathion, and p,p'-DDE. Because many factors affect the transport of pesticides from areas of application to surface water, there was not a simple correspondence between pesticide occurrence and use in the Yakima River Basin. For example, the high detection rates of atrazine, simazine, deethylatrazine, and p,p'-DDE are probably related more to their mobility and wide distribution in the hydrologic system than to their usage. Likewise, higher detection frequencies of the insecticides azinphos-methyl and carbaryl compared with chlorpyrifos appear to be related more to differences in their physical and chemical properties than to usage. The highest detection frequencies and concentrations of pesticides generally occurred during irrigation season, which is from mid-March to mid-October. Pesticides are applied during irrigation season, and runoff of excess irrigation water from fields transports them to surface water. Ground-water discharges also transport some pesticides to surface water. Atrazine, deethylatrazine, and simazine were frequently detected in samples collected after the irrigation season when there was little or no surface runoff and most of the flow in irrigation drains was derived from ground water. Daily loads of atrazine, terbacil, azinphos-methyl, and carbaryl discharged to the Yakima River from inflows between river mile 103.7 and river mile 72 varied widely between sites. For example, East Toppenish Drain discharged over 50 percent of the total load of terbacil to this reach of the Yakima River, but none of the total load of carbaryl and only about 4 percent of the total load of atrazine. Pesticide loads from the wastewater treatment plants were relatively small compared with loads from other inflows because their discharges were small. Pesticide losses, defined as the ratio of the amount discharged from a basin from May 1999 through January 2000 divided by the amount applied during 1999, were estimated for Moxee and Granger Drains and the Yakima River at Kiona. Losses ranged from less than 0.01 to 1.5 percent of pesticides applied and are comparable to those observed (0.01 to 2.2 percent) in irrigated agricultural basins in the Central Columbia Plateau of Washington State.

Washington↗

USGS1995

Simulation of ground-water flow in the Albuquerque Basin, central New Mexico, 1901-1994, with projections to 2020

This report describes a three-dimensional finite-difference ground-water-flow model of the Santa Fe Group aquifer system in the Albuquerque Basin, which comprises the Santa Fe Group (late Oligocene to middle Pleistocene age) and overlying valley and basin-fill deposits (Pleistocene to Holocene age). The model is designed to be flexible and adaptive to new geologic and hydrologic information as it becomes available, by using a geographic information system as a data-base manager to interface with the model. The aquifer system was defined and quantified in the model consistent with the current (July 1994) understanding of the structural and geohydrologic framework of the basin. Rather than putting the model through a rigorous calibration process, discrepancies between simulated and measured responses in hydraulic head were taken to indicate that the understanding of a local part of the aquifer system was incomplete or incorrect. The model simulates ground-water flow over an area of about 2,400 square miles to a depth of 1,730 to about 2,020 feet below the water table with 244 rows, 178 columns, and 11 layers. Of the 477,752 cells in the model, 310,376 are active. The top four model layers approximate the 80- foot thickness of alluvium in the incised and refilled valley of the Rio Grande to provide detail of the effect of ground-water withdrawals on the surface-water system. Away from the valley, these four layers represent the interval within the Santa Fe Group aquifer system between the computed predevelopment water table and a level 80 feet below the grade of the Rio Grande. The simulations include initial conditions (steady-state), the 1901-1994 historical period, and four possible ground-water withdrawal scenarios from 1994 to 2020. The model indicates that for the year ending in March 1994, net surface-water loss in the basin resulting from the City of Albuquerque's ground-water withdrawal totaled about 53,000 acre-feet. The balance of the about 123,000 acre-feet of withdrawal came from aquifer storage depletion (about 67,800 acre-feet) and captured or salvaged evapotranspiration (about 2,500 acrefeet). In the four scenarios projected from 1994 to 2020, City of Albuquerque annual withdrawals ranged from about 98,700 to about 177,000 acre-feet by the year 2020. The range of resulting surface-water loss was from about 62,000 to about 77,000 acre-feet. The range of aquifer storage depletion was from about 33,400 to about 95,900 acre-feet. Captured evapotranspiration and drain-return flow remained nearly constant for all scenarios. From 1994 to 2020, maximum projected declines in hydraulic head in the primary water-production zone of the aquifer (model layer 9) for the four scenarios ranged from 55 to 164 feet east of the Rio Grande and from 91 to 258 feet west of the river. Average declines in a 383.7-square-mile area around Albuquerque ranged from 28 to 65 feet in the production zone for the same period.

New Mexico↗

USGS2004

Hydrologic Effects of the 1988 Galena Fire, Black Hills Area, South Dakota

The Galena Fire burned about 16,788 acres of primarily ponderosa pine forest during July 5-8, 1988, in the Black Hills area of South Dakota. The fire burned primarily within the Grace Coolidge Creek drainage basin and almost entirely within the boundaries of Custer State Park. A U.S. Geological Survey gaging station with streamflow records dating back to 1977 was located along Grace Coolidge Creek within the burned area. About one-half of the gaging station's 26.8-square-mile drainage area was burned. The drainage basin for Bear Gulch, which is tributary to Grace Coolidge Creek, was burned particularly severely, with complete deforestation occurring in nearly the entirety of the area upstream from a gaging station that was installed in 1989. A study to evaluate effects of the Galena Fire on streamflow, geomorphology, and water quality was initiated in 1988. The geomorphologic and water-quality components of the study were completed by 1990 and are summarized in this report. A data-collection network consisting of streamflow- and precipitation-gaging stations was operated through water year 1998 for evaluation of effects on streamflow characteristics, including both annual-yield and peak-flow characteristics, which are the main focus of this report. Moderately burned areas did not experience a substantial increase in the rate of surface erosion; however, severely burned areas underwent surficial erosion nearly twice that of the unburned areas. The sediment production rate of Bear Gulch estimated 8 to 14 months after the fire was 870 ft3/acre (44 tons/acre). Substantial degradation of stream channels within the severely burned headwater areas of Bear Gulch was documented. Farther downstream, channel aggradation resulted from deposition of sediments transported from the headwater areas. The most notable water-quality effect was on concentrations of suspended sediment, which were orders of magnitude higher for Bear Gulch than for the unburned control area. Effects on several other water-quality constituents, such as organic carbon and nitrogen and phosphorus nutrient constituents, probably were influenced by the large concentrations of suspended matter that were documented in initial post-fire, storm-flow events. The first post-fire stormflow produced the highest measured concentrations of specific conductance, nitrogen, phosphorus, organic carbon, calcium, magnesium, potassium, manganese, and sulfate in the burned areas. For most constituents sampled, differences in concentrations between burned and unburned areas were no longer discernible within about 1 year following the Galena Fire. The effects of the Galena Fire on annual-yield characteristics of Grace Coolidge Creek were evaluated primarily from comparisons with long-term streamflow records for Battle Creek, which is hydrogeologically similar and is located immediately to the north. Annual yield for Grace Coolidge Creek increased by about 20 percent as a result of the fire. This estimate was based on relations between annual yield for Grace Coolidge Creek and Battle Creek for pre- and post-burn periods. Many of the post-burn data points are well beyond the range of the pre-burn data, which is a source of uncertainty for this estimate. Substantial increases in peak-flow characteristics for severely burned drainages were visually apparent from numerous post-fire field observations. Various analyses of streamflow data indicated substantial increases in peak-flow response for burned drainage areas; however, quantification of effects was particularly difficult because peak-flow response diminished quickly and returned to a generally pre-burn condition by about 1991. Field observations of vegetation and analysis of remotely sensed data indicated that establishment of grasses and forbs occurred within a similar timeframe. Comparison of pre-fire peak flows to post-1991 peak flows indicates that these grasses and forbs were equally effective in suppressing peak flows

Water-Resources Investigations Report↗

USGS1998

Depth-duration frequency of precipitation for Texas

The U.S. Geological Survey, in cooperation with the Texas Department of Transportation, conducted a study of the depth-duration frequency of precipitation for Texas. Depth-duration frequency is an estimate of the depth of precipitation for a specified duration and frequency or recurrence interval. For this report, precipitation durations of 15, 30, and 60 minutes; 1, 2, 3, 6, 12, and 24 hours; and 1, 2, 3, 5, and 7 days were investigated. The recurrence intervals for the frequencies range from 2 to 500 years. The time series of precipitation annual maxima for 173 fifteen-minute, 274 hourly, and 865 daily National Weather Service precipitation stations with at least 10 years of record in Texas provide the basis of depth-duration frequency for each identified duration. In total, about 3,030; 10,160; and 38,120 cumulative years of record are available for the 15-minute, hourly, and daily stations, respectively. L-moment statistics of the precipitation annual maxima were calculated for each duration and for each station using unbiased L-moment estimators. The statistics calculated were the mean, L-scale, L-coefficient of variation, L-skew, and L-kurtosis. The mean for each station and duration was corrected for the bias associated with fixed-interval recording of precipitation. The generalized logistic distribution was determined, using L-moment ratio diagrams, as an appropriate probability distribution for modeling the frequency of annual maxima for durations of 15 minutes to 24 hours; whereas, the generalized extreme-value distribution was determined as appropriate for durations of 1 to 7 days. The location, scale, and shape parameters of the distributions for each duration and each station were calculated from the L-moments. These parameters were contoured using spatial interpolation, based on the geostatistical method of kriging, to produce 37 maps that depict the spatial variation and magnitude of each parameter. Contour maps of the shape parameter for the generalized extreme-value distribution for durations of 1 to 7 days are not presented; the root mean square errors of preliminary maps for 1- to 7-day shape parameters were not appreciably smaller than the statewide standard deviation. Therefore, a single statewide mean shape parameter was used for 1- to 7-day durations. The depth-duration frequency for any location in Texas can be estimated using the contour maps and the equation of the corresponding distribution.

Texas↗

USGS1999

Characteristics of fractures in crystalline bedrock determined by surface and borehole geophysical surveys, eastern surplus superfund site, Meddybemps, Maine

Surface and borehole geophysical methods were used to determine fracture orientation in crystalline bedrock at the Eastern Surplus Superfund Site in Meddybemps, Maine. Fracture-orientation information is needed to address concerns about the fate of contaminants in ground water at the site. Azimuthal square-array resistivity surveys were conducted at 3 locations at the site, borehole-acoustic televiewer and borehole-video logs were collected in 10 wells, and single-hole directional radar surveys were conducted in 9 wells. Borehole-video logs were used to supplement the results of other geophysical techniques and are not described in this report. Analysis of azimuthal square-array resistivity data indicated that high-angle fracturing generally strikes northeast-southwest at the three locations. Borehole-acoustic televiewer logs detected one prominent low-angle and two prominent high-angle fracture sets. The low-angle fractures strike generally north-northeast and dip about 20 degrees west-northwest. One high-angle fracture set strikes north-northeast and dips east-southeast; the other high-angle set strikes east-northeast and dips south-southeast. Single-hole directional radar surveys identified two prominent fracture sets: a low-angle set striking north-northeast, dipping west-northwest; and a high-angle fracture set striking north-northeast, dipping east-southeast. Two additional high-angle fracture sets are defined weakly, one striking east-west, dipping north; and a second striking east-west, dipping south. Integrated results from all of the geophysical surveys indicate the presence of three primary fracture sets. A low-angle set strikes north-northeast and dips west-northwest. Two high-angle sets strike north-northeast and east-northeast and dip east-southeast and south-southeast. Statistical correction of the fracture data for orientation bias indicates that high-angle fractures are more numerous than observed in the data but are still less numerous than the low-angle fractures. The orientation and distribution of water-yielding fractures sets were determined by correlating the fracture data from this study with previously collected borehole-flowmeter data. The water-yielding fractures are generally within the three prominent fracture sets observed for the total fracture population. The low-angle water-yielding fractures primarily strike north-northeast to west-northwest and dip west-northwest to south-southwest. Most of the high-angle water-yielding fractures strike either north-northeast or east-west and dip east-southeast or south. The spacing between water-yielding fractures varies but the probable average spacing is estimated to be 30 feet for low-angle fractures; 27 feet for the east-southeast dipping, high-angle fractures; and 43 feet for the south-southeast dipping, high-angle fractures. The median estimated apparent transmissivity of individual water-yielding fractures or fracture zones was 0.3 feet squared per day and ranged from 0.01 to 382 feet squared per day. Ninety-five percent of the water-yielding fractures or fracture zones had an estimated apparent transmissivity of 19.5 feet squared per day or less. The orientation, spacing, and hydraulic properties of water-yielding fractures identified during this study can be used to help estimate recharge, flow, and discharge of ground water contaminants. High-angle fractures provide vertical pathways for ground water to enter the bedrock, interconnections between low-angle fractures, and, subsequently, pathways for water flow within the bedrock along fracture planes. Low-angle fractures may allow horizontal ground-water flow in all directions. The orientation of fracturing and the hydraulic properties of each fracture set strongly affect changes in ground-water flow under stress (pumping) conditions.

Maine↗

USGS1995

Hydrogeology and water quality at the management systems evaluation area near Piketon, Ohio

This report presents the results of a study by the U.S. Geological Survey, The Ohio State University, and the U.S. Department of Agriculture to describe the hydrology, water quality, and geochemical factors controlling water quality at the Ohio Management Systems Evaluation Area (MSEA). The Ohio MSEA is located on a 650-acre farm in the Scioto River Valley in Pike County, south-central Ohio. The farm is underlain by an incised bedrock valley filled with about 70 feet of sand and gravel outwash deposits that are covered by a veneer of silty clay alluvium and silty loam and sandy loam soils. Outwash sediment are composed predominantly of dolomite, quartz, and calcite, and have a median organic carbon concentration of 0.39 weight percent. Horizontal hydraulic conductivity of the sediment based on results of multiple-well aquifer tests ranges from 400 to 560 feet per day. Ground-water flow is from east to west-southwest at an average velocity of 1.5 to 2.5 feet per day. Ground water and surface water at the site are highly interconnected. Big Beaver Creek recharges the outwash aquifer along the eastern edge of the study area, and ground water discharges to the Scioto River at the western edge of the study area. High-stage events on the Scioto River cause frequent flow reversals in the aquifer that allow streamwater to travel a maximum observed distance of 190 feet inland. A zone of oxidizing waters (characterized by high dissolved oxygen concentration and Eh) is found in shallow ground water for several hundred feet adjacent to Big Beaver Creek and the Scioto River. This zone of oxidizing ground water is caused by the periodic inflow of surface waters to the aquifer. A ground-water budget for the study area indicates that the aquifer received 17.7 inches of recharge during water year 1992; of this amount, 72 percent originated as infiltrating precipitation, 28 percent as infiltration of surface water from Big Beaver Creek, and 0.2 percent as leakage from bedrock. Areal variation in water quality is caused by areal differences in the relative importance of these three recharge sources. The effects of bedrock leakage are evident only in the northeast corner of the study area. Here, deep outwash waters are transitional in composition between the calcium magnesium bicarbonate waters found elsewhere in the outwash aquifer and the calcium sodium chloride waters of the bedrock aquifer. Mixing calculations indicate that these deep outwash waters are composed of as much as 26 percent bedrock water. In the southern part of the MSEA, ground water is diluted by surface water from Big Beaver Creek as it recharges the aquifer through a sand and gravel streambed. At the northeast corner of the MSEA, however, Big Beaver Creek flows across a shale streambed through which no infiltration occurs. Redox reactions in the outwash aquifer control variations in aquifer chemistry with depth. From the water table to about 40 feet below land surface, oxidizing conditions are characterized by the presence of dissolved oxygen and nitrates in ground water, Eh greater than 200 millivolts, ferrihydrite coatings on sediment grains, and the absence of dissolved iron and manganese. From about 40 feet below land surface to the base of the aquifer, reducing conditions are characterized by dissolved oxygen concentrations less than 2 mg/L, Eh less than 200 millivolts, and the presence of dissolved iron and manganese. Denitrification in the reducing zone naturally remediates anthropogenic nitrate contamination of the aquifer while oxidizing pyrite in the aquifer sediment.

Ohio↗

USGS2002

Evaluation of water quality, suspended sediment, and stream morphology with an emphasis on effects of stormflow on Fountain and Monument Creek basins, Colorado Springs and vicinity, Colorado, 1981 through 2001

This report documents water quality and suspended sediment with an emphasis on evaluating the effects of stormflow on Fountain Creek Basin in the vicinity of Colorado Springs, Colorado. Water-quality data collected at 11 sites between 1981 and 2001 were used to evaluate the effects of stormflow on water quality. Suspended-sediment data collected at seven sites from 1998 through 2001 were used to evaluate effects of stormflow on suspended-sediment concentrations, discharges, and yields. Data were separated into three flow regimes: base flow, normal flow, and stormflow. A comparison of stormwater-quality concentrations measured between 1981 and 2001 to Colorado acute instream standards indicated that, except for isolated occurrences, stormwater quality met acute instream standards. At several sites, 5-day biochemical oxygen demand, fecal coliform, and selected nutrient concentrations tended to be highest during stormflow and lowest during base flow. Dissimilar to the other nutrients, dissolved nitrite plus nitrate concentrations generally were highest during base flow and lowest during stormflow. Most dissolved trace-element concentrations associated with stormflow decreased or showed little change compared to base flow. However, median concentrations of total copper, iron, lead, nickel, manganese, and zinc for stormflow samples generally were much larger than nonstorm samples. The substantially larger concentrations of total copper, iron, lead, nickel, manganese, and zinc measured at site 5800 during stormflow as compared to other sites indicates a relatively large source of these metals in the reach between sites 5530 and 5800. Semi-volatile organic compounds in samples collected during stormflow were detected relatively infrequently at the four sites monitored; however, analysis of pesticide data collected during stormflow showed a relatively frequent detection of pesticides at low levels. Nitrogen, phosphorus, and particulate trace-element loads substantially increased during stormflow. Suspended-sediment concentrations, discharges, and yields associated with stormflow were significantly greater than during normal flow. Depending on the site and year, suspended-sediment concentrations associated with storm-flow generally were 3 to10 times greater than concentrations measured during normal flow, and suspended-sediment discharges were usually more than 10 times greater during stormflow. The April through October cumulative suspended-sediment discharges and streamflows were largest in 1999 at all sites. Although large spatial variations in suspended-sediment yields occurred during normal flows, the suspended-sediment yields associated with stormflow generally were more than 10 times greater than the suspended-sediment yields that occurred during normal flow. The smallest suspended-sediment yields generally were less than 1 ton per day per square mile during stormflow. The largest suspended-sediment yields occurred at sites located in the Cottonwood Creek Basin and were greater than 10 tons per day per square mile.

Colorado↗

USGS2002

Evaluation of water quality, suspended sediment, and stream morphology with an emphasis on effects of stormwater on Fountain and Monument Creek basins, Colorado Springs and vicinity, Colorado, 1981-2001

Water-Resources Investigations Report↗

USGS2003

Occurrence and temporal variability of methyl tert -butyl ether (MTBE) and other volatile organic compounds in select sources of drinking water : results of the focused survey

The large-scale use of the gasoline oxygenate methyl tert -butyl ether (MTBE), and its high solubility, low soil adsorption, and low biodegradability, has resulted in its detection in ground water and surface water in many places throughout the United States. Studies by numerous researchers, as well as many State and local environmental agencies, have discovered high levels of MTBE in soils and ground water at leaking underground gasoline-storage-tank sites and frequent occurrence of low to intermediate levels of MTBE in reservoirs used for both public water supply and recreational boating. In response to these findings, the American Water Works Association Research Foundation sponsored an investigation of MTBE and other volatile organic compounds (VOCs) in the Nation's sources of drinking water. The goal of the investigation was to provide additional information on the frequency of occurrence, concentration, and temporal variability of MTBE and other VOCs in source water used by community water systems (CWSs). The investigation was completed in two stages: (1) reviews of available literature and (2) the collection of new data. Two surveys were associated with the collection of new data. The first, termed the Random Survey, employed a statistically stratified design for sampling source water from 954 randomly selected CWSs. The second, which is the focus of this report, is termed the Focused Survey, which included samples collected from 134 CWS source waters, including ground water, reservoirs, lakes, rivers, and streams, that were suspected or known to contain MTBE. The general intent of the Focused Survey was to compare results with the Random Survey and provide an improved understanding of the occurrence, concentration, temporal variability, and anthropogenic factors associated with frequently detected VOCs. Each sample collected was analyzed for 66 VOCs, including MTBE and three other ether gasoline oxygenates (hereafter termed gasoline oxygenates). As part of the Focused Survey, 451 source-water samples and 744 field quality-control (QC) samples were collected from 78 ground-water, 39 reservoir and (or) lake, and 17 river and (or) stream source waters at fixed intervals for a period of 1 year. Using a common assessment level of 0.2 μg/L (micrograms per liter) (2.0 μg/L for methyl ethyl ketone), 37 of the 66 VOCs analyzed were detected in both surveys. However, VOCs, especially MTBE and other gasoline oxygenates, were detected more frequently in the Focused Survey than in the Random Survey. MTBE was detected in 55.5 percent of the CWSs sampled in the Focused Survey and in 8.7 percent of those sampled in the Random Survey. Little difference in occurrence, however, was observed for trihalomethanes (THMs), which were detected in 16.4 and 14.8 percent of Focused Survey and Random Survey CWSs, respectively. This may indicate a pervasive occurrence of THMs in several source-water types, regardless of CWS size or geographic location. Using data at or above the method detection limit to assess temporal variability and anthropogenic factors associated with frequent detection of select VOCs, concentrations in the Focused Survey in ground-water, reservoir, and river source waters were typically less than 1 μg/L. Also, at a 95-percent confidence interval, no statistically significant differences were observed in comparing concentrations in the first and second ground-water sample. A weak seasonal pattern was observed in samples collected from reservoirs and lakes where gasoline oxygenates and other gasoline compounds were detected more frequently during spring and summer, presumedly a result of increased use of motorized watercraft during these seasons. In contrast, seasonal patterns were not observed in samples collected from rivers and streams. The lack of seasonal differences in river and stream source waters sampled may indicate a common and continuous source of contamination. The most frequently detected VOC (MTBE) and the two most frequently occurring subgroups of VOCs (gasoline oxygenates and THMs) detected in CWS source waters were further characterized to evaluate some anthropogenic factors that may better explain their frequent occurrence. Gasoline oxygenates were detected in 73.9 percent of all CWSs sampled. The concentration of gasoline oxygenates was slightly correlated with watercraft use on reservoirs inside MTBE high-use areas (r2=0.3783) but not outside of these areas (r2=0.0242). In general, the concentration of gasoline oxygenates increased as watercraft use increased. THMs were detected in 47.8 percent of the CWSs supplied by surface water. The frequent occurrence of THMs in reservoir source waters was determined to be an artifact of disinfection and the recycling of chlorinated water to these reservoirs. All CWSs with frequent occurrence of THMs served by a reservoir indicated that chlorine was added to waters for various reasons and that the chlorinated water was then released back to, or upstream of, the reservoir or lake that was sampled.

Water-Resources Investigations Report↗

USGS1991

Hydrology and the hypothetical effects of reducing nutrient applications on water quality in the Bald Eagle Creek Headwaters, southeastern Pennsylvania prior to implementation of agricultural best-management practices

The report characterizes a 0.43-square-mile agricultural watershed in York County, underlain by albite-chlorite and oligoclase-mica schist in the Lower Susquehanna River basin, that is being studied as part of the U.S. Environmental Protection Agency's Chesapeake Bay Program. The water quality of Bald Eagle Creek was studied from October 1985 through September 1987 prior to the implementation of Best-Management Practices to reduce nutrient and sediment discharge into Muddy Creek, a tributary to the Chesapeake Bay. About 88 percent of the watershed is cropland and pasture, and nearly 33 percent of the cropland is used for corn. The animal population is entirely dairy cattle. About 85,640 pounds of nitrogen (460 pounds per acre) and 21,800 pounds of phosphorus (117 pounds per acre) were applied to fields; 52 percent of the nitrogen and 69 percent of the phosphorus was from commercial fertilizer. Prior to fertilization, nitrate nitrogen in the soil ranged from 36 to 136 pounds per acre and phosphorus ranged from 0.89 to 5.7 pounds per acre in the top 4 feet of soil. Precipitation was about 18 percent below normal and streamflow about 35 percent below normal during the 2-year study. Eighty-four percent of the 20.44 inches of runoff was base flow. Median concentrations of total nitrogen and dissolved phosphorous in base flow were 0.05 and 0.04 milligrams per liter as phosphorus, respectively. Concentrations of dissolved nitrate in base flow increased following wet periods after crops were harvested and manure was applied. During the growing season, concentrations decreased similarly to those observed in carbonate-rock areas as nutrient uptake and evapotranspiration by corn increased. About 4,550 pounds of suspended sediment, 5,250 pounds of nitrogen, and 66.6 pounds of phosphorus discharged in base flow during the 2-year period. The suspended sediment load was about 232,000 pounds in stormflow from 26 storms that contributed 51 percent of the total stormflow. The nitrogen load was about 651 pounds and the phosphorus load was about 74 pounds in stormflow from 16 storms that contributed 28 percent of the total stormflow. It is estimated that concentrations of total nitrogen and phosphorus in base flow need to be reduced by 12 and 48 percent, respectively, to detect changes during the nutrient-management phase. Likewise, loads to total nitrogen and phosphorus in base flow need to be reduced by 62 and 57 percent.

Pennsylvania↗

USGS1985

Cost effectiveness of stream-gaging program in Michigan

This report documents the results of a study of the cost effectiveness of the stream-gaging program in Michigan. Data uses and funding sources were identified for the 129 continuous gaging stations being operated in Michigan as of 1984. One gaging station was identified as having insufficient reason to continue its operation. Several stations were identified for reactivation, should funds become available, because of insufficiencies in the data network. Alternative methods of developing streamflow information based on routing and regression analyses were investigated for 10 stations. However, no station records were reproduced with sufficient accuracy to replace conventional gaging practices. A cost-effectiveness analysis of the data-collection procedure for the ice-free season was conducted using a Kalman-filter analysis. To define missing-record characteristics, cross-correlation coefficients and coefficients of variation were computed at stations on the basis of daily mean discharge. Discharge-measurement data were used to describe the gage/discharge rating stability at each station. The results of the cost-effectiveness analysis for a 9-month ice-free season show that the current policy of visiting most stations on a fixed servicing schedule once every 6 weeks results in an average standard error of 12.1 percent for the current $718,100 budget. By adopting a flexible servicing schedule, the average standard error could be reduced to 11.1 percent. Alternatively, the budget could be reduced to $700,200 while maintaining the current level of accuracy. A minimum budget of $680,200 is needed to operate the 129-gaging-station program; a budget less than this would not permit proper service and maintenance of stations. At the minimum budget, the average standard error would be 14.4 percent. A budget of $789,900 (the maximum analyzed) would result in a decrease in the average standard error to 9.07 percent. Owing to continual changes in the composition of the network and the changes in the uncertainties of streamflow accuracy at individual stations, the cost-effectiveness analysis will need to be updated regularly if it is to be used as a management tool. Cost of these updates need to be considered in decisions concerning the feasibility of flexible servicing schedules.

Michigan↗