National Stream Quality Accounting Network Research Articles

Peak centiles of chlorpyrifos surface-water concentrations in the NAWQA and NASQAN programs

We provide upper bound estimates for peak centiles of surface water chlorpyrifos concentration readings within spatial, temporal, and land-use domains of the United States Geological Survey (USGS) National Water-Quality Assessment (NAWQA) and National Stream Quality Accounting Network (NASQAN) programs. These datasets have large overall sample sizes but variable sampling frequencies and, for chlorpyrifos, extremely high levels of non-detections. Point and interval estimates are provided for the 90th, 95th, 99th, and the 99.9th centiles, given sufficient sample size. Overall upper bound estimates for the NAWQA program over the period 1992–2011 for the 90th, 95th, 99th, and 99.9th centiles are <0.005, 0.0066, 0.0214, and 0.0852 ug/L, respectively. The estimation method is based on a survey sampling approach, finding centiles of pooled data across aggregates of site-years. Although the population quantity estimated by a pooled data centile is not the easily interpretable average of population site-year centiles, we provide strong support that it bounds this average by a combination of theory, comparison of NAWQA aggregate and direct estimates, and using modeled populations.

Isotopic composition of river water across a continent

Isotopic composition of water across United States is available and also baseline data prepared for more than 4800 samples (with depth and width-integrated stream samples) from 391 selected sites within USGS National Stream Quality Accounting Network (NASQAN). Data had been analyzed with respect to arrival at National Meteoric Water Line (NMWL). Large number of NMWL water samples has much lower slopes than 8 and intercepts ranging from +10 to −39. These lower slopes and intercepts need a re-look to ascertain coherent δ2H and δ18O across USA in precipitation. A method is worked out by plotting slopes versus intercepts on δ2H axis to arrive at the isotopic composition of water on GMWL and also to look the regional pattern that reflects the origin of vapour mass.

Toward disentangling the effect of hydrologic and nitrogen source changes from 1992 to 2001 on incremental nitrogen yield in the contiguous United States

The goal of this research was to quantify the relative impact of hydrologic and nitrogen source changes on incremental nitrogen yield in the contiguous United States. Using nitrogen source estimates from various federal data bases, remotely sensed land use data from the National Land Cover Data program, and observed instream loadings from the United States Geological Survey National Stream Quality Accounting Network program, we calibrated and applied the spatially referenced regression model SPARROW to estimate incremental nitrogen yield for the contiguous United States. We ran different model scenarios to separate the effects of changes in source contributions from hydrologic changes for the years 1992 and 2001, assuming that only state conditions changed and that model coefficients describing the stream water‐quality response to changes in state conditions remained constant between 1992 and 2001. Model results show a decrease of 8.2% in the median incremental nitrogen yield over the period of analysis with the vast majority of this decrease due to changes in hydrologic conditions rather than decreases in nitrogen sources. For example, when we changed the 1992 version of the model to have nitrogen source data from 2001, the model results showed only a small increase in median incremental nitrogen yield (0.12%). However, when we changed the 1992 version of the model to have hydrologic conditions from 2001, model results showed a decrease of approximately 8.7% in median incremental nitrogen yield. We did, however, find notable differences in incremental yield estimates for different sources of nitrogen after controlling for hydrologic changes, particularly for population related sources. For example, the median incremental yield for population related sources increased by 8.4% after controlling for hydrologic changes. This is in contrast to a 2.8% decrease in population related sources when hydrologic changes are included in the analysis. Likewise we found that median incremental yield from urban watersheds increased by 6.8% after controlling for hydrologic changes—in contrast to the median incremental nitrogen yield from cropland watersheds, which decreased by 2.1% over the same time period. These results suggest that, after accounting for hydrologic changes, population related sources became a more significant contributor of nitrogen yield to streams in the contiguous United States over the period of analysis. However, this study was not able to account for the influence of human management practices such as improvements in wastewater treatment plants or Best Management Practices that likely improved water quality, due to a lack of data for quantifying the impact of these practices for the study area.

A preliminary assessment of the spatial sources of contemporary suspended sediment in the Ohio River basin, United States, using water quality data from the NASQAN programme in a source tracing procedure

AbstractReliable information on catchment scale suspended sediment sources is required to inform the design of management strategies for helping abate the numerous environmental issues associated with enhanced sediment mobilization and off‐site loadings. Since sediment fingerprinting techniques avoid many of the logistical constraints associated with using more traditional indirect measurement methods at catchment scale, such approaches have been increasingly reported in the international literature and typically use data sets collected specifically for sediment source apportionment purposes. There remains scope for investigating the potential for using geochemical data sets assembled by routine monitoring programmes to fingerprint sediment provenance. In the United States, routine water quality samples are collected as part of the US Geological Survey's revised National Stream Quality Accounting Network programme. Accordingly, the geochemistry data generated from these samples over a 10‐year period (1996–2006) were used as the basis for a fingerprinting exercise to assess the key tributary sub‐catchment spatial sources of contemporary suspended sediment transported by the Ohio River. Uncertainty associated with the spatial source estimates was quantified using a Monte Carlo approach in conjunction with mass balance modelling. Relative frequency weighted means were used as an alternative way of summarizing the spatial source contributions, thereby avoiding the need to use confidence limits. The results should be interpreted in the context of the routine, but infrequent nature, of the suspended sediment samples used to assemble geochemistry as a basis for the sourcing exercise. Nonetheless, the study demonstrates how routine monitoring samples can be used to provide some preliminary information on sediment provenance in large drainage basins. Copyright © 2011 John Wiley &amp; Sons, Ltd.

Temporal variability of water chemistry in flowing waters of the northeastern United States: does river size matter?

AbstractThe seasonal variability of discharge, water chemistry, suspended sediment, and suspended algal abundance was examined in temperate rivers of the northeastern United States to evaluate the accepted (but rarely tested) assumption that streams are more temporally variable than large rivers. Temporal variance of discharge and water-column characteristics was determined for 108 stations on 98 rivers with data measured between May to October of 1978 by the US National Stream Quality Accounting Network (NASQAN). Temporal variance of water-column characteristics increased in relation to the mean estimate of the variable (r2 = 0.69–0.93, p 0.05). River size, estimated by median discharge, had little effect (partial r2 = 0.01–0.02, p 0.05) on the temporal variance of water-column characteristics after accounting for differences in the mean. In contrast, hydrological variability (measured by the coefficient of variation of daily discharge, flo...

Applicability of NASQAN data for ecosystem assessments on the Missouri River

AbstractThe effectiveness of ecological restoration efforts on large developed rivers is often unknown because comprehensive ecological monitoring programs are often absent. Although Eulerian water‐quality monitoring programs, such as the National Stream Quality Accounting Network (NASQAN) program, are more common, they are usually not designed for ecological assessment. Therefore, this paper addresses the value of NASQAN for ecological assessments on the Missouri River and identifies potential program additions and modifications to assess certain ecological changes in physical habitat, biological structure and function, and ecotoxicity.Five additional sites; the analysis of chlorophyll, mercury, ATP, potential endocrine disruptors, total trace elements, and selected total hydrophobic organics; and the hourly measurement of dissolved oxygen, turbidity, and temperature are recommended. Hourly measurements would require an entirely new operational aspect to NASQAN. However, the presence of data loggers and satellite transmitters in the gauging stations at all NASQAN sites substantially improves the feasibility of continuous water‐quality monitoring. The use of semipermeable membrane devices (SPMDs) to monitor dissolved bioaccumulating organics and trace elements, identification and enumeration of zooplankton, and characterization of the bioavailability of organic matter are also recommended.The effect of biological processes on the conservative assumptions that are used in flux and source determinations of NASQAN constituents are also evaluated. Organic carbon, organic nitrogen, dissolved phosphate, and dissolved inorganic nitrogen are the NASQAN constituents most vulnerable to biological processes and thus violation of conservative assumptions. Published in 2001 by John Wiley &amp; Sons, Ltd.

The National Stream Quality Accounting Network: a flux‐based approach to monitoring the water quality of large rivers

AbstractEstimating the annual mass flux at a network of fixed stations is one approach to characterizing water quality of large rivers. The interpretive context provided by annual flux includes identifying source and sink areas for constituents and estimating the loadings to receiving waters, such as reservoirs or the ocean. Since 1995, the US Geological Survey's National Stream Quality Accounting Network (NASQAN) has employed this approach at a network of 39 stations in four of the largest river basins of the USA: the Mississippi, the Columbia, the Colorado and the Rio Grande. In this paper, the design of NASQAN is described and its effectiveness at characterizing the water quality of these rivers is evaluated using data from the first 3 years of operation. A broad range of constituents was measured by NASQAN, including trace organic and inorganic chemicals, major ions, sediment and nutrients. Where possible, a regression model relating concentration to discharge and season was used to interpolate between chemical observations for flux estimation. For water‐quality network design, the most important finding from NASQAN was the importance of having a specific objective (that is, estimating annual mass flux) and, from that, an explicitly stated data analysis strategy, namely the use of regression models to interpolate between observations. The use of such models aided in the design of sampling strategy and provided a context for data review. The regression models essentially form null hypotheses for concentration variation that can be evaluated by the observed data. The feedback between network operation and data collection established by the hypothesis tests places the water‐quality network on a firm scientific footing. Published in 2001 by John Wiley &amp; Sons, Ltd.

Simulation of stream discharge and transport of nitrate and selected herbicides in the Mississippi River Basin

AbstractStream discharge and the transport of nitrate, atrazine, and metolachlor in the Mississippi River Basin were simulated using the DAFLOW/BLTM hydrologic model. The simulated domain for stream discharge included river reaches downstream from the following stations in the National Stream Quality Accounting Network: Mississippi River at Clinton, IA; Missouri River at Hermann, MO; Ohio River at Grand Chain, IL; and Arkansas River at Little Rock, AR. Coefficients of hydraulic geometry were calibrated using data from water year 1996; the model was validated by favourable simulation of observed discharges in water years 1992–1994. The transport of nitrate, atrazine, and metolachlor was simulated downstream from the Mississippi River at Thebes, IL, and the Ohio River at Grand Chain. Simulated concentrations compared favourably with observed concentrations at Baton Rouge, LA. Development of this model is a preliminary step in gaining a more quantitative understanding of the sources and fate of nutrients and pesticides delivered from the Mississippi River Basin to the Gulf of Mexico. Published in 2001 by John Wiley &amp; Sons, Ltd.

Water quality of large U.S. rivers: results from the U.S. Geological Survey's National Stream Quality Accounting Network

Water quality of large U.S. rivers: results from the U.S. Geological Survey's National Stream Quality Accounting Network

Estimating suspended sediment and trace element fluxes in large river basins: methodological considerations as applied to the NASQAN programme

AbstractIn 1994, the NASQAN (National Stream Quality Accounting Network) programme was redesigned as a flux‐based water‐quality monitoring network for the Mississippi, Columbia, Colorado, and Rio Grande Basins. As the new programme represented a departure from the original, new sampling, processing, analytical, and data handling procedures had to be selected/developed to provide data on discharge, suspended sediment concentration, and the concentrations of suspended sediment and dissolved trace elements.Annual suspended sediment fluxes were estimated by summing daily instantaneous fluxes based on predicted suspended sediment concentrations derived from discharge‐based log–log regression (rating‐curve) models. The models were developed using both historical and current site‐specific discharge and suspended sediment concentrations. Errors using this approach typically are less than ±10% for the 3‐year reporting period; however, the magnitude of the errors increases substantially for temporal spans shorter than 1 year.Total, rather than total‐recoverable, suspended sediment‐associated trace element concentrations were determined by direct analysis of material dewatered from large‐volume whole‐water samples. Site‐specific intra‐ and inter‐annual suspended sediment‐associated chemical variations were less (typically by no more than a factor of two) than those for either discharge or suspended sediment concentrations (usually more than 10‐fold). The concentrations, hence the annual fluxes, for suspended sediment‐associated phosphorus and organic carbon, determined by direct analyses, were higher than those determined using a more traditional paired, whole‐water/filtered‐water approach (by factors ranging from 1·5‐ to 10‐fold). This may be important for such issues as eutrophication and coastal productivity.Filtered water‐associated (dissolved) trace element concentrations were markedly lower than those determined during the historical NASQAN programme; many were below their respective detection limits. This resulted from the use of clean sampling, processing, and analytical protocols. Hence, the fluxes for filtered water‐associated (dissolved) Ag, Pb, Co, V, Be, Sb, and Se, as well as the total (filtered water plus suspended sediment‐associated) fluxes for these constituents, could not be estimated. Published in 2001 by John Wiley &amp; Sons, Ltd.

Distribution of oxygen‐18 and deuterium in river waters across the United States

AbstractReconstruction of continental palaeoclimate and palaeohydrology is currently hampered by limited information about isotopic patterns in the modern hydrologic cycle. To remedy this situation and to provide baseline data for other isotope hydrology studies, more than 4800, depth‐ and width‐integrated, stream samples from 391 selected sites within the USGS National Stream Quality Accounting Network (NASQAN) and Hydrologic Benchmark Network (HBN) were analysed for δ18O and δ2H (http://water.usgs.gov/pubs/ofr/ofr00‐160/pdf/ofr00‐160.pdf). Each site was sampled bimonthly or quarterly for 2·5 to 3 years between 1984 and 1987. The ability of this dataset to serve as a proxy for the isotopic composition of modern precipitation in the USA is supported by the excellent agreement between the river dataset and the isotopic compositions of adjacent precipitation monitoring sites, the strong spatial coherence of the distributions of δ18O and δ2H, the good correlations of the isotopic compositions with climatic parameters, and the good agreement between the ‘national’ meteoric water line (MWL) generated from unweighted analyses of samples from the 48 contiguous states of δ2H=8·11δ18O+8·99 (r2=0·98) and the unweighted global MWL of sites from the Global Network for Isotopes in Precipitation (GNIP) of the International Atomic Energy Agency and the World Meteorological Organization (WMO) of δ2H=8·17δ18O+10·35.The national MWL is composed of water samples that arise in diverse local conditions where the local meteoric water lines (LMWLs) usually have much lower slopes. Adjacent sites often have similar LMWLs, allowing the datasets to be combined into regional MWLs. The slopes of regional MWLs probably reflect the humidity of the local air mass, which imparts a distinctive evaporative isotopic signature to rainfall and hence to stream samples. Deuterium excess values range from 6 to 15‰ in the eastern half of the USA, along the northwest coast and on the Colorado Plateau. In the rest of the USA, these values range from −2 to 6‰, with strong spatial correlations with regional aridity. The river samples have successfully integrated the spatial variability in the meteorological cycle and provide the best available dataset on the spatial distributions of δ18O and δ2H values of meteoric waters in the USA. Published in 2001 by John Wiley &amp; Sons, Ltd.

Annual suspended sediment and trace element fluxes in the Mississippi, Columbia, Colorado, and Rio Grande drainage basins

AbstractSuspended sediment, sediment‐associated, total trace element, phosphorus (P), and total organic carbon (TOC) fluxes were determined for the Mississippi, Columbia, Rio Grande, and Colorado Basins for the study period (the 1996, 1997, and 1998 water years) as part of the US Geological Survey's redesigned National Stream Quality Accounting Network (NASQAN) programme. The majority (≥70%) of Cu, Zn, Cr, Ni, Ba, P, As, Fe, Mn, and Al are transported in association with suspended sediment; Sr transport seems dominated by the dissolved phase, whereas the transport of Li and TOC seems to be divided equally between both phases. Average dissolved trace element levels are markedly lower than reported during the original NASQAN programme; this seems due to the use of ‘clean’ sampling, processing, and analytical techniques rather than to improvements in water quality. Partitioning between sediment and water for Ag, Pb, Cd, Cr, Co, V, Be, As, Sb, Hg, and Ti could not be estimated due to a lack of detectable dissolved concentrations in most samples.Elevated suspended sediment‐associated Zn levels were detected in the Ohio River Basin and elevated Hg levels were detected in the Tennessee River, the former may affect the mainstem Mississippi River, whereas the latter probably do not. Sediment‐associated concentrations of Ag, Cu, Pb, Zn, Cd, Cr, Co, Ba, Mo, Sb, Hg, and Fe are markedly elevated in the upper Columbia Basin, and appear to be detectable (Zn, Cd) as far downstream as the middle of the basin. These elevated concentrations seem to result from mining and/or mining‐related activities. Consistently detectable concentrations of dissolved Se were found only in the Colorado River Basin.Calculated average annual suspended sediment fluxes at the mouths of the Mississippi and Rio Grande Basins were below, whereas those for the Columbia and Colorado Basins were above previously published annual values. Downstream suspended sediment‐associated and total trace element fluxes increase in the Mississippi and Columbia Basins, whereas fluxes markedly decrease in the Colorado Basin. No consistent pattern in trace element fluxes was detected in the Rio Grande Basin. Published in 2001 by John Wiley &amp; Sons, Ltd.

Regional interpretation of water‐quality monitoring data

We describe a method for using spatially referenced regressions of contaminant transport on watershed attributes (SPARROW) in regional water‐quality assessment. The method is designed to reduce the problems of data interpretation caused by sparse sampling, network bias, and basin heterogeneity. The regression equation relates measured transport rates in streams to spatially referenced descriptors of pollution sources and land‐surface and stream‐channel characteristics. Regression models of total phosphorus (TP) and total nitrogen (TN) transport are constructed for a region defined as the nontidal conterminous United States. Observed TN and TP transport rates are derived from water‐quality records for 414 stations in the National Stream Quality Accounting Network. Nutrient sources identified in the equations include point sources, applied fertilizer, livestock waste, nonagricultural land, and atmospheric deposition (TN only). Surface characteristics found to be significant predictors of land‐water delivery include soil permeability, stream density, and temperature (TN only). Estimated instream decay coefficients for the two contaminants decrease monotonically with increasing stream size. TP transport is found to be significantly reduced by reservoir retention. Spatial referencing of basin attributes in relation to the stream channel network greatly increases their statistical significance and model accuracy. The method is used to estimate the proportion of watersheds in the conterminous United States (i.e., hydrologic cataloging units) with outflow TP concentrations less than the criterion of 0.1 mg/L, and to classify cataloging units according to local TN yield (kg/km2/yr).

NUTRIENT MASS BALANCE FOR THE ALBEMARLE‐PAMLICO DRAINAGE BASIN, NORTH CAROLINA AND VIRGINIA, 19901

ABSTRACT: A 1990 nitrogen and phosphorus mass balance calculated for eight National Stream Quality Accounting Network (NASQAN) basins in the Albemarle‐Pamlico Drainage Basin indicated the importance of agricultural nonpoint sources of nitrogen and phosphorus and watershed nitrogen retention and processing capabilities. Basin total nitrogen and phosphorus input estimates were calculated for atmospheric deposition (which averaged 27 percent of total nitrogen inputs and 22 percent of total phosphorus inputs); crop fertilizer (27 and 25 percent); animal‐waste (22 and 50 percent, respectively); point sources (3 percent each of total nitrogen and total phosphorus inputs); and biological nitrogen fixation (21 percent of total nitrogen inputs). Highest in‐stream nitrogen and phosphorus loads were measured in predominantly agricultural drainage areas. Intermediate loads were observed in mixed agricultural/urban drainage areas; the lowest loads were measured in mixed agricultural/forested drainage areas. The difference between the sum of the nutrient input categories and the sum of the in‐stream nutrient loads and crop‐harvest nutrient removal was assigned to a residual category for the basin. The residual category averaged 51 percent of total nitrogen inputs and 54 percent of total phosphorus inputs.

Mississippi River Methods Comparison Study: Implications for Water Quality Monitoring of Dissolved Trace Elements

Recent reports have questioned the validity of dissolved trace element concentrations reported by the U.S. Geological Survey's National Stream Quality Accounting Network (NASQAN) as well as by other water-quality monitoring programs. To address these concerns and to evaluate the NASQAN protocols, the U.S. Geological Survey undertook the Mississippi River Methods Comparison Study. We report here the major results and implications of this study. In particular, we confirm the possible inaccuracy of previous NASQAN dissolved trace element data. The results suggest that all steps of the NASQAN protocol (sampling, processing, and analysis) require revision, though the sample filtration step appears to be of particular concern

Inadequacy of NASQAN data for assessing metal trends in the nation's rivers

Data on dissolved trace metal concentrations in east coast U.S. rivers from USGS, National Stream Quality Accounting Network are compared with data from collected and analyzed samples, suggesting the unreliability of NASQAN data in assessing trends in U.S. rivers

Trends in stream quality in the continental United States, 1978–1987

The nonparametric seasonal Kendall's test, and a related multivariate test were used to analyze 403 National Stream Quality Accounting Network (NASQAN) stations for trend for the period 1978–1987. Nominal sampling frequencies were quarterly or bimonthly. For all groups and individual constituents, trends were detected for only a minority of stations at the relatively liberal 10% significance level. The groups with the greatest percentage of trends were common ions (mostly upward) and nutrients and suspended sediment (mostly upward for total nitrogen and mostly downward for total phosphorus). In the pH and alkalinity group, the trends were dominantly upward; while this might be the result of reductions in atmospheric deposition, this hypothesis is clouded by the existence of uptrends in sulfate at many of the same stations. The trace metal analyses showed that the constituents with the greatest number of trends (dominantly downward) were arsenic and cadmium; most of the stations with downtrends were in the major population areas of the east and midwest. Additional exploratory analyses of possible relationships between trends and land use and population did not give strong evidence of possible causation.

Spatial Adequacy of Nasqan Water Quality Data in Ohio River Basin

Water quality data from 30 stations of the National Stream Quality Accounting Network (NASQAN) in the Ohio River basin were examined for spatial adequacy. A direct statistical test of differences between two sample means (for small sample size and unknown population variances) found that for over onehalf of the 53 water quality parameters, differences in water quality could not be distinguished for more than one‐third of the station pairs. An indirect statistical approach, correlating mean water quality to 136 possible explanatory basin characteristics, resulted in reasonable cause‐effect relationships for only 23 parameters. Based on a method developed to determine a spatially adequate sample size, it is recommended that the current bimonthly or quarterly sampling frequency be increased to monthly for all parameters and that the current annual reporting period be increased to four years. Other suggestions to make the system more cost‐effective are included.

Design of Nationwide Water‐Quality‐Monitoring Networks

As the agency responsible for describing and evaluating water resources of the US, the USGS has designed several networks for monitoring water quality on a national and regional scale. The largest of these, the National Stream Quality Accounting Network, is designed to monitor quantity and quality of stream flow and is described in the following.

New national water quality monitoring network

The National Stream Quality Accounting Network (NASQAN), a new water quality monitoring network designed to provide a balanced yearly picture of water quality in U.S. streams on a national and regional scale, is now in operation according to the U.S. Geological Survey. Its primary objectives are to account for the quantity and quality of water moving within and from the United States, to depict areal variability of water quality, to detect changes in stream quality, and to lay the groundwork for future assessments of changes in stream quality.In the past, attempts to document change or lack of change in water quality with time have been largely unsuccessful because of incomplete or inadequate data. Because NASQAN is set up on a national basis, has stations that are operated uniformly, and has a program that is committed to long‐term objectives, it should not have these problems.