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Cost effective stream-gaging strategies for the Lower Colorado River basin; the Blythe field office operations

This report describes the theoretical developments and illustrates the applications of techniques that recently have been assembled to analyze the cost-effectiveness of federally funded stream-gaging activities in support of the Colorado River compact and subsequent adjudications. The cost effectiveness of 19 stream gages in terms of minimizing the sum of the variances of the errors of estimation of annual mean discharge is explored by means of a sequential-search optimization scheme. The search is conducted over a set of decision variables that describes the number of times that each gaging route is traveled in a year. A gage route is defined as the most expeditious circuit that is made from a field office to visit one or more stream gages and return to the office. The error variance is defined as a function of the frequency of visits to a gage by using optimal estimation theory. Currently a minimum of 12 visits per year is made to any gage. By changing to a six-visit minimum, the same total error variance can be attained for the 19 stations with a budget of 10% less than the current one. Other strategies are also explored. (USGS)

Open-File Report↗

Nematomorph parasites indirectly alter the food web and ecosystem function of streams through behavioural manipulation of their cricket hosts.

Nematomorph parasites manipulate crickets to enter streams where the parasites reproduce. These manipulated crickets become a substantial food subsidy for stream fishes. We used a field experiment to investigate how this subsidy affects the stream community and ecosystem function. When crickets were available, predatory fish ate fewer benthic invertebrates. The resulting release of the benthic invertebrate community from fish predation indirectly decreased the biomass of benthic algae and slightly increased leaf break-down rate. This is the first experimental demonstration that host manipulation by a parasite can reorganise a community and alter ecosystem function. Nematomorphs are common, and many other parasites have dramatic effects on host phenotypes, suggesting that similar effects of parasites on ecosystems might be widespread.

Ecology Letters↗

Concentrations and loads of suspended sediment and nutrients in surface water of the Yakima River basin, Washington, 1999-2000 [electronic resource] : with an analysis of trends in concentrations

Spatial and temporal variations in concentrations and loads of suspended sediment and nutrients in surface water of the Yakima River Basin were assessed using data collected during 1999–2000 as part of the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) Program. Samples were collected at 34 sites located throughout the Basin in August 1999 using a Lagrangian sampling design, and also were collected weekly and monthly from May 1999 through January 2000 at three of the sites. Nutrient and sediment data collected at various time intervals from 1973 through 2001 by the USGS, Bureau of Reclamation, Washington State Department of Ecology, and Roza-Sunnyside Board of Joint Control were used to assess trends in concentrations. During irrigation season (mid-March to mid-October), concentrations of suspended sediment and nutrients in the Yakima River increase as relatively pristine water from the forested headwaters moves downstream and mixes with discharges from streams, agricultural drains, and wastewater treatment plants. Concentrations of nutrients also depend partly on the proportions of mixing between river water and discharges: in years of ample water supply in headwater reservoirs, more water is released during irrigation season and there is more dilution of nutrients discharged to the river downstream. For example, streamflow from river mile (RM) 103.7 to RM 72 in August 1999 exceeded streamflow in July 1988 by a factor of almost 2.5, but loads of total nitrogen and phosphorus discharged to the reach from streams, drains, and wastewater treatment plants were only 1.2 and 1.1 times larger. In years of ample water supply, canal water, which is diverted from either the Yakima or Naches River, makes up more of the flow in drains and streams carrying agricultural return flows. The canal water dilutes nutrients (especially nitrate) transported to the drains and streams in runoff from fields and in discharges from subsurface field drains and the shallow ground-water system. The average concentration of total nitrogen in drains and streams discharging to the Yakima River from RM 103.7 to RM 72 in August 1999 was 2.63 mg/L, and in July 1988 was 3.16 mg/L; average concentrations of total phosphorus were 0.20 and 0.26 mg/L. After irrigation season, streamflow in agricultural drains decreases because irrigation water is no longer diverted from the Yakima and Naches Rivers. As a result, concentrations of total nitrogen in drains increase because nitrate, which constitutes much of total nitrogen, continues to enter the drains from subsurface drains and shallow ground water. Concentrations of total phosphorus and suspended sediment often decrease, because they are transported to the drains in runoff of irrigation water from fields. In Granger Drain, concentrations of total nitrogen ranged from 2-4 mg/L during irrigation season and increased to about 6 mg/L after irrigation season, and concentrations of total phosphorus, as high as 1 mg/L, decreased to about 0.2 mg/L. In calendar year 1999, Moxee Drain transported an average of 28,000 lb/d (pounds per day) of suspended sediment, 380 lb/d of total nitrogen, and 46 lb/d of total phosphorus to the Yakima River. These loads were about half the average loads transported by Granger Drain during the same period. Average streamflows were similar for the two drains, so the difference in loads was due to differences in constituent concentrations: those in Moxee Drain were about 40-60 percent less than those in Granger Drain. Loads of suspended sediment and total phosphorus in Moxee and Granger Drains were nearly four times higher during irrigation season than during the non-irrigation season because with increased flow during irrigation season, concentrations of suspended sediment and total phosphorus are usually higher. Loads of nitrate in the drains were about the same in both seasons because nitrate concentrations are higher during the non-irrigation season. Loads of nutrients in the Yakima River at Kiona were similar during irrigation and non-irrigation season, generally differing by less than 20 percent. This is because average streamflows and concentrations of nutrients were similar between the two seasons. Average streamflow during the irrigation season was within about 6 percent of the average streamflow during the non-irrigation season and average nutrient concentrations differed by less than 13 percent. Loads of suspended sediment were about 60 percent larger during irrigation season. Large fractions of the total annual loads were transported during the first half of the irrigation season. For example, 38 percent or more of the annual loads of suspended sediment, total nitrogen, ammonia-plus-organic nitrogen, total phosphorus, and orthophosphate were transported from March through June. Departure from relations between average daily loads and annual mean streamflow suggests some reduction in loads of suspended sediment, ammonia-plus-organic nitrogen, and total nitrogen in the Yakima River at Kiona in water years 1999 and 2000. The relation between loads and streamflow was established using loads previously estimated for water years 1974, 1977, 1980, 1988, and 1989 and loads estimated by this study for other water years from 1974 through 1994. The summary of trend statistics for concentration data collected from 1991–2000 indicates that some of the factors affecting constituent transport to surface water may be common to many agricultural subbasins in the Yakima Basin. For example, concentrations of nitrate and total nitrogen increased in five of six streams and drains while concentrations of suspended solids and total phosphorus either did not change or decreased. This difference is consistent with no change, or a decrease, in amounts of suspended solids and phosphorus transported to surface water in runoff and an increase in the amount of nitrate transported to streams and drains from ground-water discharges and subsurface drains. Decreased transport of sediment and associated phosphorus to streams and drains likely results from increased use of agricultural best management practices that reduce runoff from cropland. Nitrate is less affected because much of it enters from subsurface drains and shallow ground water. Increasing concentrations of nitrate in some drains over the period 1991–2000 suggest that concentrations of nitrate in ground water are increasing. Data collected from 1997–2001 also indicate a decrease in concentrations in suspended solids and total phosphorus in some drains and streams receiving agricultural return flows. Turbidity has decreased in drains where concentrations of suspended solids have decreased. The data also indicate that concentrations of nitrate in some streams and drains have leveled off and may be decreasing. This observation does not conflict with the trend statistics for 1991–2000, but suggests that a slow increase over a decade may be leveling off. Trend statistics computed using both unadjusted and flow-adjusted data indicate small, but significant, increases in turbidity and concentrations of total phosphorus in the Yakima River at Kiona from 1991 through 2000. There was also an increase in flow-adjusted concentrations of nitrate, which is consistent with increasing concentrations of nitrate in some streams and drains flowing to the Yakima River. Although nitrogen discharged from streams and drains is a large fraction of the nitrogen load in the river, a relation between increasing concentrations of nitrate in streams and drains and increasing concentrations in the Yakima River at Kiona was not established. The trend test using flow-adjusted concentrations showed no trend in the concentration of suspended solids. This seems reasonable because concentrations of suspended solids correlated with streamflow, and higher values of both were observed after 1995.

Washington↗

Portrayal of drainage and vegetation on topographic maps

Accurate measurements of drainage networks are necessary for studies in many scientific disciplines, especially hydrology. To this end, topographic maps must show accurate classification as well as a consistent pattern of the stream network. A recent study in Georgia has developed two photo-interpretive keys which permit accurate drainage classification during the normal stereo-compilation procedures in map-making. The study was made in the Tired Creek basin in the Coastal Plain, and in the Yellow River basin in the Piedmont Province. In the Tired Creek basin, the perennial stream channels were associated with blackgum swamps which showed as a characteristic pattern on the aerial photographs of the area. Although the areas were classed as evergreen forest on specially-compiled vegetation maps without field checking, the classification was relatively consistent, indicating that the perennial channels could be identified accurately within the basin. In the Yellow River basin origins of perennial flow were found in valleys having concave-upward profiles. Valleys with convex-upward profiles remained ephemeral up to their juncture with a larger stream. Field checks indicated better than 80 percent accuracy in delineating these points of origin of perennial flow through stereoscopic viewing of the aerial photographs of the area. Vegetative difference above and below the origins of perennial flow were to subtle to be readily discerned on the photographs. Errors in classifying vegetation on special maps were attributed mainly to inexperience and to faulty criteria for for classification. Proposals are presented to improve portrayal of both drainage and vegetation on topographic maps. The proposed drainage criteria suggest portrayal of all perennial streams as well as ephemeral drainage below the first branching. The proposed vegetation criteria suggest classification of forest and shrubs, with further sub-division of distinctive patterns of vegetation easily recognized on the aerial photographs.

Open-File Report↗

Monitoring, field experiments, and geochemical modeling of Fe(II) oxidation kinetics in a stream dominated by net-alkaline coal-mine drainage, Pennsylvania, USA

Watershed-scale monitoring, field aeration experiments, and geochemical equilibrium and kinetic modeling were conducted to evaluate interdependent changes in pH, dissolved CO 2 , O 2 , and Fe(II) concentrations that typically take place downstream of net-alkaline, circumneutral coal-mine drainage (CMD) outfalls and during aerobic treatment of such CMD. The kinetic modeling approach, using PHREEQC, accurately simulates observed variations in pH, Fe(II) oxidation, alkalinity consumption, and associated dissolved gas concentrations during transport downstream of the CMD outfalls (natural attenuation) and during 6-h batch aeration tests on the CMD using bubble diffusers (enhanced attenuation). The batch aeration experiments demonstrated that aeration promoted CO 2 outgassing, thereby increasing pH and the rate of Fe(II) oxidation. The rate of Fe(II) oxidation was accurately estimated by the abiotic homogeneous oxidation rate law −d[Fe(II)]/d t = k 1 ·[O 2 ]·[H + ] − 2 ·[Fe(II)] that indicates an increase in pH by 1 unit at pH 5–8 and at constant dissolved O 2 (DO) concentration results in a 100-fold increase in the rate of Fe(II) oxidation. Adjusting for sample temperature, a narrow range of values for the apparent homogeneous Fe(II) oxidation rate constant ( k 1 ′) of 0.5–1.7 times the reference value of k 1 = 3 × 10 −12 mol/L/min (for pH 5–8 and 20 °C), reported by Stumm and Morgan (1996), was indicated by the calibrated models for the 5-km stream reach below the CMD outfalls and the aerated CMD. The rates of CO 2 outgassing and O 2 ingassing in the model were estimated with first-order asymptotic functions, whereby the driving force is the gradient of the dissolved gas concentration relative to equilibrium with the ambient atmosphere. Although the progressive increase in DO concentration to saturation could be accurately modeled as a kinetic function for the conditions evaluated, the simulation of DO as an instantaneous equilibrium process did not affect the model results for Fe(II) or pH. In contrast, the model results for pH and Fe(II) were sensitive to the CO 2 mass transfer rate constant ( k L , CO2 a). The value of k L , CO2 a estimated for the stream (0.010 min −1 ) was within the range for the batch aeration experiments (0–0.033 min −1 ). These results indicate that the abiotic homogeneous Fe(II) oxidation rate law, with adjustments for variations in temperature and CO 2 outgassing rate, may be applied to predict changes in aqueous iron and pH for net-alkaline, ferruginous waters within a stream (natural conditions) or a CMD treatment system (engineered conditions).

Pennsylvania↗

Evaluating the potential for remote bathymetric mapping of a turbid, sand-bed river: 1. Field spectroscopy and radiative transfer modeling

Remote sensing offers an efficient means of mapping bathymetry in river systems, but this approach has been applied primarily to clear-flowing, gravel bed streams. This study used field spectroscopy and radiative transfer modeling to assess the feasibility of spectrally based depth retrieval in a sand-bed river with a higher suspended sediment concentration (SSC) and greater water turbidity. Attenuation of light within the water column was characterized by measuring the amount of downwelling radiant energy at different depths and calculating a diffuse attenuation coefficient, K d . Attenuation was strongest in blue and near-infrared bands due to scattering by suspended sediment and absorption by water, respectively. Even for red wavelengths with the lowest values of K d , only a small fraction of the incident light propagated to the bed, restricting the range of depths amenable to remote sensing. Spectra recorded above the water surface were used to establish a strong, linear relationship ( R 2 = 0.949) between flow depth and a simple band ratio; even under moderately turbid conditions, depth remained the primary control on reflectance. Constraints on depth retrieval were examined via numerical modeling of radiative transfer within the atmosphere and water column. SSC and sensor radiometric resolution limited both the maximum detectable depth and the precision of image-derived depth estimates. Thus, although field spectra indicated that the bathymetry of turbid channels could be remotely mapped, model results implied that depth retrieval in sediment-laden rivers would be limited to shallow depths (on the order of 0.5 m) and subject to a significant degree of uncertainty.

Water Resources Research↗

Assessment of conservation practices in the Fort Cobb Reservoir watershed, southwestern Oklahoma

The Fort Cobb Reservoir watershed encompasses about 813 square kilometers of rural farm land in Caddo, Custer, and Washita Counties in southwestern Oklahoma. The Fort Cobb Reservoir and six stream segments were identified on the Oklahoma 1998 303(d) list as not supporting designated beneficial uses because of impairment by nutrients, suspended solids, sedimentation, pesticides, and unknown toxicity. As a result, State and Federal agencies, in collaboration with conservation districts and landowners, started conservation efforts in 2001 to decrease erosion and transport of sediments and nutrients to the reservoir and improve water quality in tributaries. The U.S. Department of Agriculture selected the Fort Cobb Reservoir watershed in 2003 as 1 of 14 benchmark watersheds under the Conservation Effectiveness Assessment Project with the objective of quantifying the environmental benefits derived from agricultural conservation programs in reducing inflows of sediments and phosphorus to the reservoir. In November 2004, the Biologic, Geographic, Geologic, and Water Disciplines of the U.S. Geological Survey, in collaboration with the Agricultural Research Service, Grazinglands Research Laboratory in El Reno, Oklahoma, began an interdisciplinary investigation to produce an integrated publication to complement this program. This publication is a compilation of 10 report chapters describing land uses, soils, geology, climate, and water quality in streams and the reservoir through results of field and remote sensing investigations from 2004 to 2007. The investigations indicated that targeting best-management practices to small intermittent streams draining to the reservoir and to the Cobb Creek subwatershed may effectively augment efforts to improve eutrophic to hypereutrophic conditions that continue to affect the reservoir. The three major streams flowing into the reservoir contribute nutrients causing eutrophication, but minor streams draining cultivated fields near the reservoir appeared to be disproportionate contributors of nutrients. Increasing conservation practices on small streams may have a greater effect in mitigating eutrophication in the reservoir than additional installation of such measures on the larger creeks.

Oklahoma↗

Influence of diurnal variations in stream temperature on streamflow loss and groundwater recharge

We demonstrate that for losing reaches with significant diurnal variations in stream temperature, the effect of stream temperature on streambed seepage is a major factor contributing to reduced afternoon streamflows. An explanation is based on the effect of stream temperature on the hydraulic conductivity of the streambed, which can be expected to double in the 0° to 25°C temperature range. Results are presented for field experiments in which stream discharge and temperature were continuously measured for several days over losing reaches at St. Kevin Gulch, Colorado, and Tijeras Arroyo, New Mexico. At St. Kevin Gulch in July 1991, the diurnal stream temperature in the 160-m study reach ranged from about 4° to 18°C, discharges ranged from 10 to 18 L/s, and streamflow loss in the study reach ranged from 2.7 to 3.7 L/s. On the basis of measured stream temperature variations, the predicted change in conductivity was about 38%; the measured change in stream loss was about 26%, suggesting that streambed temperature varied less than the stream temperature. At Tijeras Arroyo in May 1992, diurnal stream temperature in the 655-m study reach ranged from about 10° to 25°C and discharge ranged from 25 to 55 L/s. Streamflow loss was converted to infiltration rates by factoring in the changing stream reach surface area and streamflow losses due to evaporation rates as measured in a hemispherical evaporation chamber. Infiltration rates ranged from about 0.7 to 2.0 m/d, depending on time and location. Based on measured stream temperature variations, the predicted change in conductivity was 29%; the measured change in infiltration was also about 27%. This suggests that high infiltration rates cause rapid convection of heat to the streambed. Evapotranspiration losses were estimated for the reach and adjacent flood plain within the arroyo. On the basis of these estimates, only about 5% of flow loss was consumed via stream evaporation and stream-side evapotranspiration, indicating that 95% of the loss within the study reach represented groundwater recharge.

Water Resources Research↗

Field guide for collecting samples for analysis of volatile organic compounds in stream water for the National Water-Quality Assessment Program

For many years, stream samples for analysis of volatile organic compounds have been collected without specific guidelines or a sampler designed to avoid analyte loss. In 1996, the U.S. Geological Survey's National Water-Quality Assessment Program began aggressively monitoring urban stream-water for volatile organic compounds. To assure representative samples and consistency in collection procedures, a specific sampler was designed to collect samples for analysis of volatile organic compounds in stream water. This sampler, and the collection procedures, were tested in the laboratory and in the field for compound loss, contamination, sample reproducibility, and functional capabilities. This report describes that sampler and its use, and outlines field procedures specifically designed to provide contaminant-free, reproducible volatile organic compound data from stream-water samples. These guidelines and the equipment described represent a significant change in U.S. Geological Survey instructions for collecting and processing stream-water samples for analysis of volatile organic compounds. They are intended to produce data that are both defensible and interpretable, particularly for concentrations below the microgram-per-liter level. The guidelines also contain detailed recommendations for quality-control samples.

Open-File Report↗

Simulation of Ground-Water Flow and Areas Contributing Recharge to Production Wells in Contrasting Glacial Valley-Fill Settings, Rhode Island

Areas contributing recharge and sources of water to a production well field in the Village of Harrisville and to a production well field in the Town of Richmond were delineated on the basis of calibrated, steady-state ground-water-flow models representing average hydrologic conditions. The study sites represent contrasting glacial valley-fill settings. The area contributing recharge to a well is defined as the surface area where water recharges the ground water and then flows toward and discharges to the well. In Harrisville, the production well field is composed of three wells in a narrow, approximately 0.5-mile-wide, valley-fill setting on opposite sides of Batty Brook, a small intermittent stream that drains 0.64 square mile at its confluence with the Clear River. Glacial stratified deposits are generally less areally extensive than previously published. The production wells are screened in a thin (30 feet) but transmissive aquifer. Paired measurements of ground-water and surface-water levels indicated that the direction of flow between the brook and the aquifer was generally downward during pumping conditions. Long-term mean annual streamflow from two streams upgradient of the well field totaled 0.72 cubic feet per second. The simulated area contributing recharge for the 2005 average well-field withdrawal rate of 224 gallons per minute extended upgradient to ground-water divides in upland areas and encompassed 0.17 square mile. The well field derived 62 percent of pumped water from intercepted ground water and 38 percent from infiltrated stream water from the Batty Brook watershed. For the maximum simulated well-field withdrawal of 600 gallons per minute, the area contributing recharge expanded to 0.44 square mile to intercept additional ground water and infiltration of stream water; the percentage of water derived from surface water, however, was the same as for the average pumping rate. Because of the small size of Batty Brook watershed, most of the precipitation recharge in the watershed was withdrawn by the well field at the maximum rate either by intercepted ground water or indirectly by infiltrated stream water. Because the production wells are screened in a thin and transmissive aquifer in a small watershed, simulated ground-water traveltimes from recharge locations to the discharging wells were relatively short: 93 percent of the traveltimes were 10 years or less. In Richmond, the production well field is composed of two wells adjacent to and east of the Wood River in a moderately broad, approximately 1.2-mile-wide, valley-fill setting. The wells are screened in a transmissive aquifer with saturated thickness greater than 60 feet. Streamflow measurements in Baker Brook, a tributary to the Wood River 0.4 mile north of the well-field site, indicated that natural net loss of streamflow between the upland-valley contact and a downstream site was 0.12 cubic feet per second under average hydrologic conditions. Simulated areas contributing recharge for the maximum well-field pumping rate of 675 gallons per minute and for one-half the maximum rate extended northeastward from the well field to ground-water divides in upland areas. The area contributing recharge also included a remote, isolated area on the opposite side of the Wood River from the well field. The model simulation indicated that the well field did not derive any of its water from the Wood River because of the large watershed and associated quantity of ground water available for capture by the well field. The area contributing recharge for one-half the maximum rate was 0.31 square mile and the primary source of water to the well field was direct precipitation recharge. Fifteen percent of the water withdrawn from the production wells, however, was obtained from Baker Brook, indicating the importance of even small, distant tributary streams to the contributing area to a well. The area contributing recharge on the opposite side of the Wood River is

Scientific Investigations Report↗

Effects of streambank fencing of pasture land on benthic macroinvertebrates and the quality of surface water and shallow ground water in the Big Spring Run basin of Mill Creek watershed, Lancaster County, Pennsylvania, 1993-2001

Streambank fencing along stream channels in pastured areas and the exclusion of pasture animals from the channel are best-management practices designed to reduce nutrient and suspended-sediment yields from drainage basins. Establishment of vegetation in the fenced area helps to stabilize streambanks and provides better habitat for wildlife in and near the stream. This study documented the effectiveness of a 5- to 12-foot-wide buffer strip on the quality of surface water and near-stream ground water in a 1.42-mi2 treatment basin in Lancaster County, Pa. Two miles of stream were fenced in the basin in 1997 following a 3- to 4-year pre-treatment period of monitoring surface- and ground-water variables in the treatment and control basins. Changes in surface- and ground-water quality were monitored for about 4 years after fence installation. To alleviate problems in result interpretation associated with climatic and hydrologic variation over the study period, a nested experimental design including paired-basin and upstream/downstream components was used to study the effects of fencing on surface-water quality and benthic-macroinvertebrate communities. Five surface-water sites, one at the outlet of a 1.77-mi2 control basin (C-1), two sites in the treatment basin (T-3 and T-4) that were above any fence installation, and two sites (one at an upstream tributary site (T-2) and one at the outlet (T-1)) that were treated, were sampled intensively. Low-flow samples were collected at each site (approximately 25-30 per year at each site), and stormflow was sampled with automatic samplers at all sites except T-3. For each site where stormflow was sampled, from 35 to 60 percent of the storm events were sampled over the entire study period. Surface-water sites were sampled for analyses of nutrients, suspended sediment, and fecal streptococcus (only low-flow samples), with field parameters (only low-flow samples) measured during sample collection. Benthic-macroinvertebrate samples were collected in May and September of each year; samples were collected at the outlet of the control and treatment basins and at three upstream sites, two in the treatment basin and one in the control basin. For each benthic-macroinvertebrate sample: Stream riffles and pools were sampled using the kick-net method; habitat was characterized using Rapid Bioassessment Protocols (RBP); water-quality samples were collected for nutrients and suspended sediment; stream field parameters were measured; and multiple biological metrics were calculated. The experimental design to study the effects of fencing on the quality of near-stream shallow ground water involved a nested well approach. Two well nests were in the treatment basin, one each at surface-water sites T-1 and T-2. Within each well nest, the data from one deep well and three shallow wells (no greater than 12 ft deep) were used for regional characterization of ground-water quality. At each site, two of the shallow wells were inside the eventual fence (treated wells); the other shallow well was outside the eventual fence (control well). The wells were sampled monthly, primarily during periods with little to no recharge, for laboratory analysis of nutrients and fecal streptococcus; field parameters of water quality also were measured.

Pennsylvania↗

Implementing landscape connectivity with topographic filtering model: A simulation of suspended sediment delivery in an agricultural watershed

The widespread availability of high-fidelity topography combined with advances in geospatial analysis offer the opportunity to reimagine approaches to the difficult problem of predicting sediment delivery from watersheds. Here we present a model that uses high-resolution topography to filter sediment sources to quantify sediment delivery to the watershed outlet. It is a reduced-complexity, top-down model that defines transfer functions—topographic filters—between spatially distributed sediment sources and spatially integrated sediment delivery. The goal of the model is to forecast changes in watershed suspended sediment delivery in response to spatially distributed changes in sediment source magnitude or delivery, whether a result of watershed drivers or intentional management actions. Such an application requires the context of a watershed model that accounts for all sediment sources, enforces sediment mass balance throughout the spatial domain, and accommodates sediment storage and delivery over time. The model is developed for a HUC-8 watershed with a flat upland dominated by corn-soybean agriculture and deeply incised valleys near the watershed outlet with large sediment contributions from near-channel sources. Topofilter computes delivery and storage of field-derived sediment according to its spatial and structural connectivity to the stream channel network; subsequently, delivery of both field- and near-channel-derived sediment along with floodplain storage are computed in the stream channel network to the watershed outlet. The model outputs provide a spatially rich representation of sediment delivery and storage on field and along the stream that is consistent with available independent information on sediment accumulations and fluxes. Rather than a single best-calibrated solution, Topofilter uses the Generalized Likelihood Uncertainty Estimate (GLUE) approach to develop many possible solutions with sediment delivery rates expressed as probability distributions across the watershed. The ensemble of simulation outputs provides a useful basis for estimating uncertainty in sediment delivery and the effectiveness of different landscape management allocation across a watershed.

Minnesota↗

National Water-Quality Assessment Program; summary of pesticide data collected on Whites Bayou near Anahuac, Texas, March to September 1994

One water-quality monitoring site was established on Whites Bayou, at the downstream end of the study area. Sampling began in March 1994 and will continue for 1 year. Sampling frequency ranges from four times per month in May and June to once per month in July. Stream-stage measurements were made three times per week from April to September. Field measurements during sampling include stream stage and discharge, water temperature, pH, dissolved oxygen, and specific conductance. Laboratory analyses include major inorganic ions, nutrients, sediment, and pesticides.

Texas↗

The discovery and development of the El Dorado (Kansas) oil field

Pioneers named El Dorado, Kansas, in 1857 for the beauty of the site and the promise of future riches but not until 58 years later was black rather than mythical yellow gold discovered when the Stapleton No. 1 oil well came in on October 5, 1915. El Dorado's leaders were envious when nearby towns found huge gas fields and thrived. John Donley, an El Dorado barber, had tried to find either gas or oil in 1878 at a nearby site selected by a spiritualist. He staked out a townsite, spudded a well and drilled 200 feet before running out of money. Wells in 1879 and 1882 produced only brine. In June, 1914, chafed over discovery of oil in nearby Augusta, El Dorado city fathers contracted with Erasmus Haworth, soon to retire from his position as State Geologist, to perform a geological study of the area. His field work outlined the El Dorado Anticline, which unsuccessfully was drilled first in August, 1915. On abandonment, the Wichita Natural Gas Company purchased the lease and drilled the Stapleton No. 1 oil well. More success followed and by 1918, the El Dorado produced 29 million barrels, almost 9% of the nation's oil. Entrepreneurs came and prospered: the Cities Service Oil Company, A.L. Derby, Jack Vickers, and Bill Skelly all became familiar names in Midcontinent oil marketing. Earlier giant fields had hurt the price of crude oil but the El Dorado came in as both World War I and the rapid popularization of motor transport made a market for both light and heavy ends of the refinery stream. The giant gas field never materialized as hoped but in late 1995, the El Dorado Field produced its 300 millionth barrel of oil.

Northeastern Geology and Environmental Sciences↗

Hydrologic assessment of the Upper Dorr Run Watershed, Hocking County, Ohio, 1998

The Upper Dorr Run Watershed in Hocking County, Ohio, has been mined several times for coal and clay since 1913 and is a significant source of acid mine drainage to the Hocking River. To assess the surface-water hydrology of the site, a topographic map showing the location of springs and other hydrologic features of interest was prepared using aerial photography and field surveying and mapping techniques. Discharge and water-quality measurements at six springs and one stream site were made during field investigations in June 1998. Discharge and water quality observed at a downstream weir on Upper Dorr Run represents the combined discharge from springs plus ground-water inflow. Discharges from springs to surface water were generally small (less than 0.3 cubic foot per second), but one spring constituted 56 percent of the total discharge measured at the downstream weir. The total flow at an intermediate measurement site was less than the combined discharge of the upgradient springs because of evaporation, transpiration, and ground-water flow beneath the stream channel. The total flow at the weir was greater than the combined discharge of all springs, primarily because two potential sources of water were not included in field measurements. The water quality in Upper Dorr Run is strongly affected by acid mine drainage as indicated by pH less than 4, elevated acidity, and elevated concentrations of dissolved sulfate and dissolved iron. Concentrations of chemical constituents in the water were lower at the downstream weir than at the source springs because of residence times in ponds and chemical interactions between the water and the atmosphere. Acidity loads during the sampling period were significantly higher from the Lower Kittanning (No. 5) coal (272 kilograms per day) than from the Upper Kittanning (No. 6) coal (17.7 kilograms per day). Comparison of data obtained in 1998 to data obtained in 1982 showed that quality of water of selected sampling sites had not changed appreciably in 16 years.

Water-Resources Investigations Report↗

Evaluation of Metal Toxicity in Streams Affected by Abandoned Mine Lands, Upper Animas River Watershed, Colorado

Acid drainage from abandoned mines and from naturally-acidic rocks and soil in the upper Animas River watershed of Colorado generates elevated concentrations of acidity and dissolved metals in stream waters and deposition of metal-contaminated particulates in streambed sediments, resulting in both toxicity and habitat degradation for stream biota. High concentrations of iron (Fe), aluminum (Al), zinc (Zn), copper (Cu), cadmium (Cd), and lead (Pb) occur in acid streams draining headwaters of the upper Animas River watershed, and high concentrations of some metals, especially Zn, persist in circumneutral reaches of the Animas River and Mineral Creek, downstream of mixing zones of acid tributaries. Seasonal variation of metal concentrations is reflected in variation in toxicity of stream water. Loadings of dissolved metals to the upper Animas River and tributaries are greatest during summer, during periods of high stream discharge from snowmelt and monsoonal rains, but adverse effects on stream biota may be greater during winter low-flow periods, when stream flows are dominated by inputs of groundwater and contain greatest concentrations of dissolved metals. Fine stream-bed sediments of the upper Animas River watershed also contain elevated concentrations of potentially toxic metals. Greatest sediment metal concentrations occur in the Animas River upstream from Silverton, where there are extensive deposits of mine and mill tailings, and in mixing zones in the Animas River and lower Mineral Creek, where precipitates of Fe and Al oxides also contain high concentrations of other metals. This report summarizes the findings of a series of toxicity studies in streams of the upper Animas River watershed, conducted on-site and in the laboratory between 1998 and 2000. The objectives of these studies were: (1) to determine the relative toxicity of stream water and fine stream-bed sediments to fish and invertebrates; (2) to determine the seasonal range of toxicity in stream water; (3) to develop site-specific thresholds for toxicity of Zn and Cu in stream water; and (4) to develop models of the contributions of Cu and Zn to toxicity of stream water, which may be used to characterize toxicity before and after planned remediation efforts. We evaluated the toxicity of metal-contaminated sediments by conducting sediment toxicity tests with two species of benthic invertebrates, the midge, Chironomus tentans. and the amphipod, Hyalella azteca. Laboratory toxicity tests with both taxa, exposed to fine stream-bed sediments collected in September 1997, showed some evidence of sediment toxicity, as survival of midge larvae in sediments from Cement Creek (C48) and lower Mineral Creek (M34), and growth of amphipods in sediments from these sites and three Animas River sites (A68, Animas at Silverton; A72, Animas below Silverton, and A73, Animas at Elk Park) were significantly reduced compared to a reference site, South Mineral Creek (SMC) . Amphipods were also exposed to site water and fine stream-bed sediment, separately and in combination, during the late summer low flow period (August-September) of 1998. In these studies, stream water, with no sediment present, from all five sites tested (same sites as above, except C48) caused 90% to 100% mortality of amphipods. In contrast, significant reductions in survival of amphipods occurred at two sites (A72 and SMC) in exposures with field-collected sediment plus stream water, and at only one site (A72) in exposures with sediments and clean overlying water. Concentrations of Zn, Pb, Cu, and Cd were high in both sediment and pore water (interstitial water) from most sites tested, but greatest sediment toxicity was apparently associated with greater concentrations of Fe and/or Al in sediments. These results suggest that fine stream-bed sediments of the more contaminated stream reaches of the upper Animas River watershed are toxic to benthic invertebrates, but that these impacts are less serious than tox

Biological Science Report↗