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At least 199 records · Page 11Linked to original sources
USGS2009

One Northwest community - People, salmon, rivers, and the sea: Towards sustainable salmon fisheries

Pacific salmon management is in crisis. Throughout their range, salmon and steelhead populations are being adversely affected by human activities. Without coordinated, effective, and timely action, the future of the Pacific salmon resource is most certainly in doubt. To address the challenges that are currently facing salmon management, concerned citizens representing a diverse array of government agencies and non-governmental organizations have agreed to cooperate in the development of a Sustainable Fisheries Strategy for west coast salmon and steelhead populations. The Strategy builds on the contents of this book, resulting from the Sustainable Fisheries Conference and subsequent community- and watershed-based citizen forums. This chapter presents the key elements of the Strategy including a common vision for the future, a series of guiding principles, and specific strategies for supporting sustainable fisheries. As such, the Strategy embraces an ecosystem-based approach to managing human activities, rather than the traditional egocentric approach to managing salmonid populations and associated habitats. A system of community-based, watershed-oriented councils, including all stakeholders and agency representatives, is proposed for effective transition to ecosystem-based salmon and steelhead management. It is our hope that everyone involved in Pacific salmon management will embrace both the spirit and the specific elements of the Sustainable Fisheries Strategy as we face the difficult challenges ahead.

Book chapter↗
USGS2009

Setting the stage for a sustainable Pacific salmon fisheries strategy

Salmon and steelhead Oncorhynchus spp., have been keystone species for ecosystems and human cultures of the North American Pacific coast for cons. Yet, in the past century, many populations have been greatly diminished and some are now extinct-the result of a combination of factors, including habitat loss and degradation, overfishing, natural variability in salmon production, negative effects of artificial propagation, and weaknesses in institutional and regulatory structures. We argue that a major shift is required, from the egocentric environmental approach (wherein each part of the ecosystem is managed as a unit) to the ecocentric ecosystem approach (wherein all parts are integrated for management). A management framework is proposed that contains-for each management unit such as a watershed-four elements: management goals; management objectives, ecosystem indicators; and a coordinated action plan. We also describe the Sustainable Fisheries Strategy, a consultative process for developing an ecosystem-based approach toward achieving sustainable Pacific salmon and steelhead populations and fisheries. This book is one of three important underpinnings of the Strategy; the other two are the Strategy itself and a manual being developed to guide community-based programs embracing the principles of sustainable fisheries. This book contains important historical perspectives as well as numerous innovative ideas for moving toward ecosystem-oriented, sustainable management of Pacific salmon and steelhead.

Book chapter↗
USGS2017

The effect of composition of selected groundwaters from the Basin and Range Province on plutonium, neptunium, and Americium speciation

The speciation of plutonium, neptunium, and americium was determined in groundwaters from four sources in the Basin and Range Province: the lower carbonate aquifer, Nevada Test Site (NTS) (Crystal Pool); alluvial fill, Frenchman Flat, NTS (well 5C); Hualapai Valley, Arizona (Red Lake south well); and Tularosa Basin, New Mexico (Rentfrow well). The results were interpreted to indicate that plutonium and, to a lesser extent, neptunium are least soluble in reducing groundwaters containing a large concentration of sulfate ion and a small concentration of strongly complexing anions. The results further emphasize the desirability of including studies such as this among the other site-selection criteria for nuclear waste repositories.

Arizoan, Nevada, New Mexico↗
USGS2017

Plutonium, americium, and neptunium speciation in selected groundwaters

As part of a continuing study, plutonium, americium, and neptunium speciation was determined at 25 and 90°C in four groundwaters from diverse sources: the Sparta aquifer in Louisiana, near the Vacherie salt dome; Mansfield No. 2 well in the Palo Duro Basin, Texas; the Stripa mine in Sweden; and the Waste Isolation Pilot Plant (WIPP) in New Mexico. Plutonium generally was soluble in Sparta and Stripa waters, regardless of temperature or initial oxidation state. Solubility in Mansfield water was high, except in 90 °C experiments using low-oxidation-state plutonium. The WIPP water had the least ability to maintain plutonium in solution; solubility after 30 days exceeded 50% only in experiments at 25 °C using Pu(V) and Pu(VI). Neptunium generally was soluble in all waters and was present exclusively as Np(V) and Np(VI), regardless of initial oxidation state. The solubility of americium was consistently high in Sparta groundwater at both temperatures and in Mansfield and WIPP waters at 25°C, but was < 50% after 30 days in Stripa water at both temperatures and in Mansfield and WIPP waters at 90°C. The results indicated that plutonium and neptunium solubilities were determined by the oxidation-reduction properties of the waters, i.e., their abilities to convert these elements to soluble oxidation states. This was not the case for americium, however; Am(IV) was not detected, and the solubility of this element was determined entirely by the chemical properties of Am(III).

Nuclear Technology↗
USGS2017

Leaching of plutonium from a radioactive waste glass by eight groundwaters from the western United States

The leachability of a radioactive waste glass formulated to Battelle Pacific Northwest Laboratory specification 80-270 has been studied using eight actual groundwaters with a range of chemical compositions as leachants. Waters collected from the Grande Ronde Basalt (Washington State) and from alluvial deposits in the Hualapai Valley (Arizona) were the most effective at removing plutonium from this glass. Leaching was shown to be incongruent; plutonium was removed from the glass more slowly than the overall glass matrix. The results of these experiments indicate the need to study the leachability of actual waste forms using the actual projected groundwaters that are most likely to come into contact with the waste should a radioactive waste repository be breached.

western United States↗
USGS2013

Nitrogen cycling responses to mountain pine beetle disturbance in a high elevation whitebark pine ecosystem

Ecological disturbances can significantly affect biogeochemical cycles in terrestrial ecosystems, but the biogeochemical consequences of the extensive mountain pine beetle outbreak in high elevation whitebark pine (WbP) (Pinus albicaulis) ecosystems of western North America have not been previously investigated. Mountain pine beetle attack has driven widespread WbP mortality, which could drive shifts in both the pools and fluxes of nitrogen (N) within these ecosystems. Because N availability can limit forest regrowth, understanding how beetle-induced mortality affects N cycling in WbP stands may be critical to understanding the trajectory of ecosystem recovery. Thus, we measured above- and belowground N pools and fluxes for trees representing three different times since beetle attack, including unattacked trees. Litterfall N inputs were more than ten times higher under recently attacked trees compared to unattacked trees. Soil inorganic N concentrations also increased following beetle attack, potentially driven by a more than two-fold increase in ammonium (NH4+) concentrations in the surface soil organic horizon. However, there were no significant differences in mineral soil inorganic N or soil microbial biomass N concentrations between attacked and unattacked trees, implying that short-term changes in N cycling in response to the initial stages of WbP attack were restricted to the organic horizon. Our results suggest that while mountain pine beetle attack drives a pulse of N from the canopy to the forest floor, changes in litterfall quality and quantity do not have profound effects on soil biogeochemical cycling, at least in the short-term. However, continuous observation of these important ecosystems will be crucial to determining the long-term biogeochemical effects of mountain pine beetle outbreaks.

Montana↗
USGS2025

Effect of copper mill waste material on benthic invertebrates and zooplankton diversity and abundance

Copper (Cu) stamp mill mining in North America from the early 1900s produced a pulverized ore by-product now known as stamp sands (SS). In a mining operation near the city of Gay (Michigan, USA), SS were originally deposited near a Lake Superior beach, but erosion and wave action have moved many SS into beaches and reefs that are critical spawning and nursery areas for native fish (e.g., Lake Whitefish). Larval and juvenile native fish consume zooplankton and benthic invertebrates during their development, and many of these invertebrate taxa may be sensitive to metal contamination from the SS. Here, we sampled the invertebrate community from beaches with high SS, moderate SS and low SS, as well as a control beach 58 km from the source of the SS. The high SS site was characterized by fewer benthic taxa, and less density of several taxa than the low SS site, especially benthic copepods. All beaches had comparable zooplankton diversity, but the abundance was ~ 2 orders of magnitude lower at the high SS site. Cu and several other metals were elevated at beaches with more SS. We found support for associations between benthic density and diversity with depth (positive effect) and Cu concentration (negative effect). Cu concentration was a better predictor of declines in benthic invertebrate abundance and diversity than SS although sensitivity to Cu varied among taxa. We also observed that the relationship between Cu concentration and SS was non-linear, and highly variable. For example, 149 mg Cu/kg dry weight sediment is a consensus threshold used in the literature to identify Cu toxicity, but the prediction interval for estimating that concentration of Cu from measurements of SS is 26-851 mg Cu/kg dry weight. A better predictive model of this relationship would be beneficial to develop an understanding of what level of SS reduction would prevent Cu impacts on invertebrates.

Michigan↗
USGS2021

Technique to estimate generalized skew coefficients of annual peak streamflow for natural watershed conditions in Texas, Oklahoma, and eastern New Mexico

Reliable information about the frequency of annual peak streamflow is needed for floodplain management, objective assessment of flood risk, and cost-effective design of dams, levees, other flood-control structures, and roads, bridges, and culverts. Generalized skew coefficients are among the data needed for log-Pearson type III peak-streamflow frequency analyses of annual peak streamflows. A technique is presented to estimate generalized skew coefficients used for log-Pearson type III peak-streamflow frequency analyses of annual peak streamflow from natural watersheds (minimal regulation and minimal impervious cover). The estimation of generalized skew coefficients was based on annual and historical peak streamflow data from an initial set of 444 selected USGS streamgaging stations (streamgages) with at least 30 years of recorded annual peak streamflows from natural watersheds in Texas, Oklahoma, and the part of New Mexico east of the Great Continental Divide. The primary focus was to obtain information that could be used to update previously published generalized skew coefficients in Texas. Of the 444 candidate streamgages, 341 were used in the final construction of statistical models. Two generalized additive models (GAMs) were used to predict generalized skew based on a 2-dimensional smooth on projected Albers equal area coordinates of either (1) the locations of the centroids of the gaged watersheds or (2) the streamgage locations. To create maps of generalized skew coefficients, predictions were made on a 1-kilometer grid and contour lines were superimposed. The centroid-location map, with a mean-squared error (MSE) of 0.216, is preferred. Generalized skew coefficients from the centroid-location map, along with the MSE, are useful for computing weighted-skew values when conducting frequency analyses of annual peak streamflow following the guidelines set forth in Bulletin 17C. Based on the results of the study, text revision of the TxDOT Hydraulic Design Manual could be made.

New Mexico, Oklahoma, Texas↗
USGS2010

Experimental drought in a tropical rain forest increases soil carbon dioxide losses to the atmosphere

Climate models predict precipitation changes for much of the humid tropics, yet few studies have investigated the potential consequences of drought on soil carbon (C) cycling in this important biome. In wet tropical forests, drought could stimulate soil respiration via overall reductions in soil anoxia, but previous research suggests that litter decomposition is positively correlated with high rainfall fluxes that move large quantities of dissolved organic matter (DOM) from the litter layer to the soil surface. Thus, reduced rainfall could also limit C delivery to the soil surface, reducing respiration rates. We conducted a throughfall manipulation experiment to investigate how 25% and 50% reductions in rainfall altered both C movement into soils and the effects of those DOM fluxes on soil respiration rates. In response to the experimental drought, soil respiration rates increased in both the −25% and −50% treatments. Throughfall fluxes were reduced by 26% and 55% in the −25% and −50% treatments, respectively. However, total DOM fluxes leached from the litter did not vary between treatments, because the concentrations of leached DOM reaching the soil surface increased in response to the simulated drought. Annual DOM concentrations averaged 7.7 ± 0.8, 11.2 ± 0.9, and 15.8 ± 1.2 mg C/L in the control, −25%, and −50% plots, respectively, and DOM concentrations were positively correlated with soil respiration rates. A laboratory incubation experiment confirmed the potential importance of DOM concentration on soil respiration rates, suggesting that this mechanism could contribute to the increase in CO 2 fluxes observed in the reduced rainfall plots. Across all plots, the data suggested that soil CO 2 fluxes were partially regulated by the magnitude and concentration of soluble C delivered to the soil, but also by soil moisture and soil oxygen availability. Together, our data suggest that declines in precipitation in tropical rain forests could drive higher CO 2 fluxes to the atmosphere both via increased soil O 2 availability and through responses to elevated DOM concentrations.

Golfo Dulce Forest Reserve↗
USGS2025

Machine learning generated streamflow drought forecasts for the Conterminous United States (CONUS): Developing and evaluating an operational tool to enhance sub-seasonal to seasonal streamflow drought early warning for gaged locations

Forecasts of streamflow drought, when streamflow declines below typical levels, are notably less available than for floods or meteorological drought, despite widespread impacts. To address this gap, we apply machine learning (ML) models to forecast streamflow drought 1-13 weeks into the future at > 3,000 streamgage locations across the conterminous United States (CONUS). We applied two ML methods (Long short-term memory (LSTM) neural networks; Light Gradient-Boosting Machine - LightGBM) and two benchmark model approaches (persistence; Autoregressive Integrated Moving Average - ARIMA) to predict weekly streamflow percentiles with independent models for each forecast horizon. To explore whether a training focus on dry weeks improved performance, both ML models were trained using all percentiles (LSTM-all, LightGBM-all) and only percentiles below 30% (LSTM<30, LightGBM<30). We evaluated model performance regionally and nationally for drought occurrence (the classification performance for a future date) and for drought onset/termination (performance identifying drought starts and ends). ML models generally performed worse than the persistence model for discrete classification (moderate, severe, extreme drought) of drought occurrence but exceeded the benchmark models for onset/termination. ML models outperformed benchmarks in predicting continuous streamflow percentiles below 30%. Occurrence performance was better for less intense droughts and shorter forecast horizons, with the ML models having predictive power at 1-4 week horizons for severe droughts (10th percentile threshold). All models struggled to forecast onset, though the best ML model was the LSTM<30 (sensitivity of 22%). Termination performance was greater, with the drought termination performance greatest for the LightGBM-all model. When estimating model uncertainty, the LSTM<30 model had the narrowest 90% percentile interval with closest to optimal capture. This work highlights the challenges and opportunities to further advance hydrological drought forecasting and supports an experimental operational streamflow drought assessment and forecast tool.

Continental United States↗
USGS2004

Synthesis of rainfall and runoff data used for Texas Department of Transportation Research Projects 0-4193 and 0-4194

In the early 2000s, the Texas Department of Transportation funded several research projects to examine the unit hydrograph and rainfall hyetograph techniques for hydrologic design in Texas for the estimation of design flows for stormwater drainage systems. A research consortium comprised of Lamar University, Texas Tech University, the University of Houston, and the U.S. Geological Survey (USGS), was chosen to examine the unit hydrograph and rainfall hyetograph techniques. Rainfall and runoff data collected by the USGS at 91 streamflow-gaging stations in Texas formed a basis for the research. These data were collected as part of USGS small-watershed projects and urban watershed studies that began in the late 1950s and continued through most of the 1970s; a few gages were in operation in the mid-1980s. Selected hydrologic events from these studies were available in the form of over 220 printed reports, which offered the best aggregation of hydrologic data for the research objectives. Digital versions of the data did not exist. Therefore, significant effort was undertaken by the consortium to manually enter the data into a digital database from the printed record. The rainfall and runoff data for over 1,650 storms were entered. To enhance data integrity, considerable quality-control and quality-assurance efforts were conducted as the database was assembled and after assembly to enhance data integrity. This report documents the database and informs interested parties on its usage.

Texas↗
USGS2023

Responses of juvenile mussels to metals in sediment and water of the Tri-State Mining District

The U.S. Geological Survey and collaborators from EcoAnalysts, Inc., completed field and laboratory studies during 2016–19 to evaluate the toxicity of metals to freshwater mussels in streams draining the Tri-State Mining District. This project consisted of (1) sampling and analysis of metals in water and sediment, (2) surveys of mussel assemblages at sites with suitable mussel habitat, (3) toxicity tests with juvenile mussels exposed to zinc or to a mixture of metals (zinc, lead, and cadmium) in water, and (4) toxicity tests to evaluate the contributions of metals in sediment and metals in overlying water to toxic effects on mussels. Field sampling at sites in the Spring River and Neosho River and their tributaries demonstrated wide ranges of metal contamination in water and sediment. Zinc was the predominant toxic metal in water, and concentrations of lead and cadmium were much lower. Mussel areal density and species richness were greater at reference sites with low sediment metal concentrations (for example, zinc, 29–141 micrograms per gram) than at test sites that had higher concentrations of sediment zinc (416–3,420 micrograms per gram) as a result of effects of upstream mining activity. Juvenile mussels were highly sensitive to zinc in water in 12-week toxicity tests compared to previous water-only tests, and adding low levels of waterborne lead and cadmium typical of their occurrence in Tri-State Mining District streams produced greater toxicity. Thresholds for mussel toxicity were at or less than waterborne metal concentrations detected in Tri-State Mining District streams, and sites with waterborne metal concentrations exceeding thresholds had decreased mussel density and decreased mussel species richness. The 12-week toxicity tests with juvenile mussels in Tri-State Mining District sediments also demonstrated negative mussel responses with metal exposure. Thresholds for reductions in survival, growth, or biomass were at sediment metal concentrations less than thresholds reported for previous 4-week tests. We documented strong associations between reduced survival in laboratory tests and reduced species richness in community surveys. Attempts to estimate combined toxicity thresholds for metals in sediment and overlying water were not successful. These inconclusive results may be attributable to several factors, including (1) unexpected losses of waterborne metals from solution, (2) differences in sensitivity of different age/size classes of juvenile mussels, (3) disruption of sediment-water equilibria and changes in metal bioavailability, and (4) behavioral or physiological responses allowing juvenile mussels to temporarily reduce or avoid metal exposure. We also observed differences in metal toxicity thresholds between sediment toxicity tests started with different ages/sizes of test organisms. A followup study that combined exposure to Tri-State Mining District sediments with exposures to multiple levels of waterborne metals demonstrated toxic effects of sediments with low metal concentrations; however, some treatments also indicated unexpected reversals of concentration-response trends and reduced toxicity in treatments that had high metal concentrations in overlying water. These unusual responses may reflect development of physiological tolerance to metal toxicity by induction of metal-binding proteins (for example, metallothionein) in response to high metal levels in water. Results of laboratory and field studies indicated strong associations between metal exposure in Tri-State Mining District streams and toxic effects on juvenile freshwater mussels. Mussel community characteristics corresponded to differences in metal concentrations in sediment and water among Tri-State Mining District sampling sites. Responses of juvenile mussels in 12-week water and sediment exposures were strongly correlated with the status of mussel assemblages in Tri-State Mining District streams. The combined results support the hypothesis that exposure to metals from historical mining activities adversely affects freshwater mussel communities in the Spring River/Neosho River drainage.

Kansas, Missouri, Oklahoma↗
USGS2025

Preparation and analysis methods for fish tissue collected from Lake Koocanusa, Montana

Lake Koocanusa, a reservoir, receives mine wastes from metallurgical coal mines in the Elk River Valley of British Columbia, Canada. Selenium and other elements discharged by the mines into the waters of the United States can pose unknown risks to aquatic life. The U.S. Geological Survey Wyoming-Montana Water Science Center can collaborate with Montana Fish, Wildlife and Parks and other State and Federal agencies to design studies and to collect fish tissues to help fill this knowledge gap. This report describes the processes, techniques, and methods used to collect and analyze fish tissue collected from Lake Koocanusa; and procedures used to review and manage data, including quality assurance and quality control procedures used by the U.S. Geological Survey Wyoming-Montana Water Science Center and supporting analytical laboratories. These fish tissue collections began in 2021.

Montana↗
USGS2006

Statistical characteristics of storm interevent time, depth, and duration for eastern New Mexico, Oklahoma, and Texas

The design of small runoff-control structures, from simple floodwater-detention basins to sophisticated best-management practices, requires the statistical characterization of rainfall as a basis for cost-effective, risk-mitigated, hydrologic engineering design. The U.S. Geological Survey, in cooperation with the Texas Department of Transportation, has developed a framework to estimate storm statistics including storm interevent times, distributions of storm depths, and distributions of storm durations for eastern New Mexico, Oklahoma, and Texas. The analysis is based on hourly rainfall recorded by the National Weather Service. The database contains more than 155 million hourly values from 774 stations in the study area. Seven sets of maps depicting ranges of mean storm interevent time, mean storm depth, and mean storm duration, by county, as well as tables listing each of those statistics, by county, were developed. The mean storm interevent time is used in probabilistic models to assess the frequency distribution of storms. The Poisson distribution is suggested to model the distribution of storm occurrence, and the exponential distribution is suggested to model the distribution of storm interevent times. The four-parameter kappa distribution is judged as an appropriate distribution for modeling the distribution of both storm depth and storm duration. Preference for the kappa distribution is based on interpretation of L-moment diagrams. Parameter estimates for the kappa distributions are provided. Separate dimensionless frequency curves for storm depth and duration are defined for eastern New Mexico, Oklahoma, and Texas. Dimension is restored by multiplying curve ordinates by the mean storm depth or mean storm duration to produce quantile functions of storm depth and duration. Minimum interevent time and location have slight influence on the scale and shape of the dimensionless frequency curves. Ten example problems and solutions to possible applications are provided.

New Mexico, Oklahoma, Texas↗
USGS2004

Empirical, dimensionless, cumulative-rainfall hyetographs developed from 1959-86 storm data for selected small watersheds in Texas

A database of incremental cumulative-rainfall values for storms that occurred in small urban and rural watersheds in north and south central Texas during the period from 1959 to 1986 was used to develop empirical, dimensionless, cumulative-rainfall hyetographs. Storm-quartile classifications were determined from the cumulative-rainfall values, which were divided into data groups on the basis of storm-quartile classification (first, second, third, fourth, and first through fourth combined), storm duration (0 to 6, 6 to 12, 12 to 24, 24 to 72, and 0 to 72 hours), and rainfall amount (1 inch or more). Removal of long leading tails, in effect, shortened the storm duration and, in some cases, affected the storm-quartile classification. Therefore, two storm groups, untrimmed and trimmed, were used for analysis. The trimmed storms generally are preferred for interpretation. For a 12-hour or less trimmed storm duration, approximately 49 percent of the storms are first quartile. For trimmed storm durations of 12 to 24 and 24 to 72 hours, 47 and 38 percent, respectively, of the storms are first quartile. For a trimmed storm duration of 0 to 72 hours, the first-, second-, third-, and fourth-quartile storms accounted for 46, 21, 20, and 13 percent of all storms, respectively. The 90th-percentile curve for first-quartile storms indicated about 90 percent of the cumulative rainfall occurs during the first 20 percent of the storm duration. The 10th-percentile curve for first-quartile storms indicated about 30 percent of the cumulative rainfall occurs during the first 20 percent of the storm duration. The 90th-percentile curve for fourth-quartile storms indicated about 33 percent of the cumulative rainfall occurs during the first 20 percent of the storm duration. The 10th-percentile curve for fourth-quartile storms indicated less than 5 percent of the cumulative rainfall occurs during the first 20 percent of the storm duration. Statistics for the empirical, dimensionless, cumulative-rainfall hyetographs are presented in the report along with hyetograph curves and tables. The curves and tables presented do not present exact mathematical relations but can be used to estimate distributions of rainfall with time for small drainage areas of less than about 160 square miles in urban and small rural watersheds in north and south central Texas.

Texas↗
USGS2011

A method for estimating peak and time of peak streamflow from excess rainfall for 10- to 640-acre watersheds in the Houston, Texas, metropolitan area

Estimates of peak and time of peak streamflow for small watersheds (less than about 640 acres) in a suburban to urban, low-slope setting are needed for drainage design that is cost-effective and risk-mitigated. During 2007-10, the U.S. Geological Survey (USGS), in cooperation with the Harris County Flood Control District and the Texas Department of Transportation, developed a method to estimate peak and time of peak streamflow from excess rainfall for 10- to 640-acre watersheds in the Houston, Texas, metropolitan area. To develop the method, 24 watersheds in the study area with drainage areas less than about 3.5 square miles (2,240 acres) and with concomitant rainfall and runoff data were selected. The method is based on conjunctive analysis of rainfall and runoff data in the context of the unit hydrograph method and the rational method. For the unit hydrograph analysis, a gamma distribution model of unit hydrograph shape (a gamma unit hydrograph) was chosen and parameters estimated through matching of modeled peak and time of peak streamflow to observed values on a storm-by-storm basis. Watershed mean or watershed-specific values of peak and time to peak ("time to peak" is a parameter of the gamma unit hydrograph and is distinct from "time of peak") of the gamma unit hydrograph were computed. Two regression equations to estimate peak and time to peak of the gamma unit hydrograph that are based on watershed characteristics of drainage area and basin-development factor (BDF) were developed. For the rational method analysis, a lag time (time-R), volumetric runoff coefficient, and runoff coefficient were computed on a storm-by-storm basis. Watershed-specific values of these three metrics were computed. A regression equation to estimate time-R based on drainage area and BDF was developed. Overall arithmetic means of volumetric runoff coefficient (0.41 dimensionless) and runoff coefficient (0.25 dimensionless) for the 24 watersheds were used to express the rational method in terms of excess rainfall (the excess rational method). Both the unit hydrograph method and excess rational method are shown to provide similar estimates of peak and time of peak streamflow. The results from the two methods can be combined by using arithmetic means. A nomograph is provided that shows the respective relations between the arithmetic-mean peak and time of peak streamflow to drainage areas ranging from 10 to 640 acres. The nomograph also shows the respective relations for selected BDF ranging from undeveloped to fully developed conditions. The nomograph represents the peak streamflow for 1 inch of excess rainfall based on drainage area and BDF; the peak streamflow for design storms from the nomograph can be multiplied by the excess rainfall to estimate peak streamflow. Time of peak streamflow is readily obtained from the nomograph. Therefore, given excess rainfall values derived from watershed-loss models, which are beyond the scope of this report, the nomograph represents a method for estimating peak and time of peak streamflow for applicable watersheds in the Houston metropolitan area. Lastly, analysis of the relative influence of BDF on peak streamflow is provided, and the results indicate a 0:04log 10 cubic feet per second change of peak streamflow per positive unit of change in BDF. This relative change can be used to adjust peak streamflow from the method or other hydrologic methods for a given BDF to other BDF values; example computations are provided.

Texas↗
USGS2023

Effects of lead exposure on birds breeding in the Southeast Missouri Lead Mining District

Lead mining in the Southeast Missouri Lead Mining District began in the 1700s and continued for nearly 300 years; the waste piles associated with smelting, mining, and milling of lead ores have released metal residues that have contaminated soil and water in the region. Previous studies in the district have indicated potential harm to wildlife, including birds, because of elevated lead concentrations associated with mining. Exposure to soil-borne lead was correlated with elevated lead concentrations in tissues, inhibition of δ-aminolevulinic acid dehydratase (δALAD), and renal lesions in birds foraging on ground-dwelling invertebrates at contaminated sites (compared to reference sites) in the Southeast Missouri Lead Mining District. This study assessed reproductive outcomes for songbirds exposed to soil-borne lead in the district, examined the relation between lead concentrations in soils and in tissues of ground-feeding birds and prey species, and compared the results to literature-based toxicity thresholds for lead that are associated with negative effects in birds. Three lead-contaminated sites and three reference sites (with background concentrations of lead and no known mining inputs) were compared in two ways: individually to all other sites or by site type. Additional effects of lead exposure were evaluated by examining concentrations of biomarkers (oxidative stress, lipid peroxidation, and deoxyribonucleic acid damage) in liver tissues, δALAD inhibition, and renal and hepatic microscopic lesions in birds from lead-contaminated and reference sites. Lead concentrations in soil were site-dependent and were also generally heterogeneous within the lead-contaminated sites. Between 17 and 74 percent of all soil samples at contaminated sites had lead concentrations that exceeded a threshold (1,000 milligrams per kilogram [mg/kg] lead in soil) previously associated with adverse physiological effects in birds in the Southeast Missouri Lead Mining District. Lead concentrations in mixed invertebrates from lead-contaminated sites (282 to 2,230 mg/kg dry weight [dw]) indicated that consuming soil-dwelling prey species is a potential exposure pathway for adult birds and their broods. At lead-contaminated sites, lead concentrations in 40.5 percent of blood samples (adults and their broods) were within a subclinical effects range (0.9 to 2.3 mg/kg dw), and 18.7 percent of samples had lead concentrations that exceeded clinical effects criteria (greater than 2.3 mg/kg dw). In contrast, only 2.6 percent of blood samples from reference sites were within the subclinical effects range for lead; all other blood samples from the reference sites had lead concentrations representative of background concentrations (less than 0.9 mg/kg dw). Subclinical and clinical threshold exceedances for lead concentrations in livers and kidneys were similarly more prevalent at the contaminated sites compared to the reference sites. Lead concentrations in blood were positively correlated with lead concentrations in soil, livers, and kidneys. Lead concentrations in blood were negatively correlated with δALAD activity; greater than 50 percent of the birds collected at lead-contaminated sites exhibited injury via greater than 50 percent inhibition of δALAD in blood compared to birds at reference sites. Birds with elevated lead concentrations in tissues also exhibited enhanced oxidative stress. Microscopic lesions in the livers and kidneys of birds had similar rates of occurrence at the contaminated and reference sites, and lesion prevalence could not be directly linked to lead exposure. Reproductive success was monitored at 585 nests, and 3 out of 5 species had reduced nest success associated with elevated lead concentrations in soil; habitat measures did not help explain nest success. Reduced nest success may have resulted from greater nest predation resulting from neurological and behavioral effects of lead exposure. Ultimately, these lines of evidence indicate that bird health and reproduction have been negatively affected by exposure to lead-contaminated soils in the Southeast Missouri Lead Mining District.

Missouri↗