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At least 289 records · Page 16Linked to original sources
USGS2013

Sources and characteristics of organic matter in the Clackamas River, Oregon, related to the formation of disinfection by-products in treated drinking water

This study characterized the amount and quality of organic matter in the Clackamas River, Oregon, to gain an understanding of sources that contribute to the formation of chlorinated and brominated disinfection by-products (DBPs), focusing on regulated DBPs in treated drinking water from two direct-filtration treatment plants that together serve approximately 100,000 customers. The central hypothesis guiding this study was that natural organic matter leaching out of the forested watershed, in-stream growth of benthic algae, and phytoplankton blooms in the reservoirs contribute different and varying proportions of organic carbon to the river. Differences in the amount and composition of carbon derived from each source affects the types and concentrations of DBP precursors entering the treatment plants and, as a result, yield varying DBP concentrations and species in finished water. The two classes of DBPs analyzed in this study-trihalomethanes (THMs) and haloacetic acids (HAAs)-form from precursors within the dissolved and particulate pools of organic matter present in source water. The five principal objectives of the study were to (1) describe the seasonal quantity and character of organic matter in the Clackamas River; (2) relate the amount and composition of organic matter to the formation of DBPs; (3) evaluate sources of DBP precursors in the watershed; (4) assess the use of optical measurements, including in-situ fluorescence, for estimating dissolved organic carbon (DOC) concentrations and DBP formation; and (5) assess the removal of DBP precursors during treatment by conducting treatability "jar-test" experiments at one of the treatment plants. Data collection consisted of (1) monthly sampling of source and finished water at two drinking-water treatment plants; (2) event-based sampling in the mainstem, tributaries, and North Fork Reservoir; and (3) in-situ continuous monitoring of fluorescent dissolved organic matter (FDOM), turbidity, chlorophyll- a , and other constituents to continuously track source-water conditions in near real-time. Treatability tests were conducted during the four event-based surveys to determine the effectiveness of coagulant and powdered activated carbon (PAC) on the removal of DBP precursors. Sample analyses included DOC, total particulate carbon (TPC), total and dissolved nutrients, absorbance and fluorescence spectroscopy, and, for regulated DBPs, concentrations of THMs and HAAs in finished water and laboratory-based THM and HAA formation potentials (THMFP and HAAFP, respectively) for source water and selected locations throughout the watershed. The results of this study may not be typical given the record and near record amounts of precipitation that occurred during spring that produced streamflow much higher than average in 2010-11. Although there were algal blooms, lower concentrations of chlorophyll- a were observed in the water column during the study period compared to historical data. Concentrations of DBPs in finished (treated) water averaged 0.024 milligrams per liter (mg/L) for THMs and 0.022 mg/L for HAAs; maximum values were about 0.040 mg/L for both classes of DBPs. Although DBP concentrations were somewhat higher within the distribution system, none of the samples collected for this study or for the quarterly compliance monitoring by the water utilities exceeded levels permissible under existing U.S. Environmental Protection Agency (USEPA) regulations: 0.080 mg/L for THMs and 0.060 mg/L for HAAs. DOC concentrations were generally low in the Clackamas River, typically about 1.0-1.5 mg/L. Concentrations in the mainstem occasionally increased to nearly 2.5 mg/L during storms; DOC concentrations in tributaries were sometimes much higher (up to 7.8 mg/L). The continuous in-situ FDOM measurements indicated sharp rises in DOC concentrations in the mainstem following rainfall events; concentrations were relatively stable during summer base flow. Even though the first autumn storm mobilized appreciable quantities of carbon, higher concentrations of DBPs in finished water were observed 3-weeks later, after the ground was saturated from additional rainfall. The majority of the DOC in the lower Clackamas River appears to originate from the upper basin, suggesting terrestrial carbon was commonly the dominant source. Lower-basin tributaries typically contained the highest concentrations of DOC and DBP precursors and contributed substantially to the overall loads in the mainstem during storms. During low-flow periods, tributaries were not major sources of DOC or DBP precursors to the Clackamas River. Although the dissolved fraction of organic carbon contributed the majority of DBP precursors, at times the particulate fraction (inorganic sediment and organic particles including detritus and algal material) contributed a substantial fraction of DBP precursors. Considering just the main-stem sites, on average, 10 percent of THMFP and 32 percent of HAAFP were attributed to particulate carbon. This finding suggests water-treatment methods that remove particles prior to chlorination would reduce finished-water DBP concentrations to some degree. Overall, concentrations of THM and HAA precursors were closely linked to DOC concentrations; laboratory DBP formation potentials (DBPFPs) clearly showed that THMFP and HAAFP were greatest in the downstream tributaries that contained elevated carbon concentrations. However, carbon-normalized "specific" formation potentials for THMs and HAAs (STHMFP and SHAAFP, respectively) revealed changes in carbon character over time that affected the two types of DBP classes differently. HAA precursors were elevated in waters containing aromatic-rich soil-derived material arising from forested areas. In contrast, THM precursors were associated with carbon having a lower aromatic content; highest STHMFP occurred in autumn 2011 in the mainstem from North Fork Reservoir downstream to LO DWTP. This pattern suggests the potential for a link between THM precursors and algal-derived carbon. The highest STHMFP value was measured within North Fork Reservoir, indicating reservoir derived carbon may be important for this class of DBPs. Weak correlations between STHMFP and SHAAFP emphasize that precursor sources for these types of DBPs may be different. This highlights not only that different locations within the watershed produce carbon with different reactivity (specific DBPFP), but also that different management approaches for each class of DBP precursors could be required for control. Treatability tests conducted on source water during four basin-wide surveys demonstrated that an average of about 40 percent of DOC can be removed by coagulation. While the decrease in THMFP following coagulation was similar to DOC, the decrease in HAAFP was much greater (approximately 70 percent), indicating coagulation is particularly effective at removing HAA precursors'likely because of the aromatic nature of the carbon associated with HAA precursors. Several findings from this study have direct implications for managing drinking-water resources and for providing useful information that may help improve treatment-plant operations. For example, the use of in-situ fluorometers that measure FDOM provided an excellent proxy for DOC concentration in this system and revealed short-term, rapid changes in DOC concentration during storm events. In addition, the strong correlation between FDOM values measured in-situ and HAA5 concentrations in finished water may permit estimation of continuous HAA concentrations, as was done here. As part of this study, multiple in-situ FDOM sensors were deployed continuously and in real-time to characterize the composition of dissolved organic matter. Although the initial results were promising, additional research and engineering developments will be needed to demonstrate the full utility of these sensors for this purpose. In conclusion, although DBPFPs were strongly correlated to DOC concentration, some DBPs formed from particulate carbon, including terrestrial leaf material and algal material such as planktonic species of blue-green algae and sloughed filaments, stalks, and cells of benthic algae. Different precursor sources in the watershed were evident from the data, suggesting specific actions may be available to address some of these sources. In-situ measurements of FDOM proved to be an excellent proxy for DOC concentration as well as HAA formation during treatment, which suggests further development and refinement of these sensors have the potential to provide real-time information about complex watershed processes to operators at the drinking-water treatment plants. Follow-up studies could examine the relative roles that terrestrial and algal sources have on the DBP precursor pool to better understand how watershed-management activities may be affecting the transport of these compounds to Clackamas River drinking-water intakes. Given the low concentrations of algae in the water column during this study, additional surveys during more typical river conditions could provide a more complete understanding of how algae contribute DBP precursors. Further development of FDOM-sensor technology can improve our understanding of carbon dynamics in the river and how concentrations may be trending over time. This study was conducted in collaboration with Clackamas River Water and the City of Lake Oswego water utilities. Other research partners included Oregon Health and Science University in Hillsboro, Oregon, Alexin Laboratory in Tigard, Oregon, U.S. Geological Survey National Research Program Laboratory in Denver, Colorado, and the U.S. Geological Survey Water Science Centers in Portland, Oregon, and Sacramento, California. This project was supported with funding from Clackamas River Water, City of Lake Oswego, the U.S. Geological Survey, and the Water Research Foundation.

Oregon↗
USGS2007

Evaluation of a non-point source pollution model, AnnAGNPS, in a tropical watershed

Impaired water quality caused by human activity and the spread of invasive plant and animal species has been identified as a major factor of degradation of coastal ecosystems in the tropics. The main goal of this study was to evaluate the performance of AnnAGNPS (Annualized Non-Point Source Pollution Model), in simulating runoff and soil erosion in a 48 km2 watershed located on the Island of Kauai, Hawaii. The model was calibrated and validated using 2 years of observed stream flow and sediment load data. Alternative scenarios of spatial rainfall distribution and canopy interception were evaluated. Monthly runoff volumes predicted by AnnAGNPS compared well with the measured data (R2 = 0.90, P < 0.05); however, up to 60% difference between the actual and simulated runoff were observed during the driest months (May and July). Prediction of daily runoff was less accurate (R2 = 0.55, P < 0.05). Predicted and observed sediment yield on a daily basis was poorly correlated (R2 = 0.5, P < 0.05). For the events of small magnitude, the model generally overestimated sediment yield, while the opposite was true for larger events. Total monthly sediment yield varied within 50% of the observed values, except for May 2004. Among the input parameters the model was most sensitive to the values of ground residue cover and canopy cover. It was found that approximately one third of the watershed area had low sediment yield (0-1 t ha-1 y-1), and presented limited erosion threat. However, 5% of the area had sediment yields in excess of 5 t ha-1 y-1. Overall, the model performed reasonably well, and it can be used as a management tool on tropical watersheds to estimate and compare sediment loads, and identify "hot spots" on the landscape. ?? 2007 Elsevier Ltd. All rights reserved.

Environmental Modelling and Software↗
USGS2023

Diet composition and resource overlap of sympatric native and introduced salmonids across neighboring streams during a peak discharge event

Species assemblages composed of non-native and native fishes are found in freshwater systems throughout the world, and interactions such as interspecific competition that may negatively affect native species are expected when non-native species are present. In the Smith River watershed, Montana, rainbow trout were introduced by 1930. Native mountain whitefish and non-native rainbow trout have presumably occurred in sympatry since the introduction of rainbow trout; however, knowledge about how these two species compete with one another for food resources is sparse. We quantified diet compositions of rainbow trout and mountain whitefish in the mainstem Smith River and in a tributary to the Smith River—Sheep Creek—to determine the degree of overlap in the diets of mountain whitefish and rainbow trout in the Smith River and between the mainstem Smith River and a tributary stream. Rainbow trout and mountain whitefish had generalist feeding strategies, which probably contribute to the amicable coexistence of these species. Diet overlap between rainbow trout and mountain whitefish was high (Pianka’s index value = 0.85) in the Smith River and moderate in Sheep Creek (Pianka’s index value = 0.57). Despite overlap in diets, some resource partitioning may alleviate resource competition (e.g., rainbow trout consumed far more Oligochaeta than mountain whitefish but fewer Brachycentridae and Chironomidae). Diet composition of rainbow trout and mountain whitefish did not differ greatly between the Smith River and Sheep Creek. Prey categories most commonly used by mountain whitefish at the population and individual levels (i.e., Ephemeroptera and Trichoptera) are sensitive taxa and many species within these orders have experienced extinctions and population declines. Therefore, future changes in resource availability or competition could be of concern.

Montana↗
USGS2019

Enhancement of primary production during drought in a temperate watershed is greater in larger rivers than headwater streams

Drought is common in rivers, yet how this disturbance regulates metabolic activity across network scales is largely unknown. Drought often lowers gross primary production (GPP) and ecosystem respiration (ER) in small headwaters but by contrast can enhance GPP and cause algal blooms in downstream estuaries. We estimated ecosystem metabolism across a nested network of 13 reaches from headwaters to the main stem of the Connecticut River from 2015 through 2017, which encompassed a pronounced drought. During drought, GPP and ER increased, but with greater enhancement in larger rivers. Responses of GPP and ER were partially due to warmer temperatures associated with drought, particularly in the larger rivers where temperatures during summer drought were > 10°C higher than typical summer baseflow. The larger rivers also had low canopy cover, which allowed primary producers to take advantage of lower turbidity and fewer cloudy days during drought. We conclude that GPP is enhanced by higher temperature, lower turbidity, and longer water residence times that are all a function of low discharge, but ecosystem response in temperate watersheds to these drivers depends on light availability regulated by riparian canopy cover. In larger rivers, GPP increased more than ER during drought, even leading to temporary autotrophy, an otherwise rare event in the typically light‐limited heterotrophic Connecticut River main stem. With climate change, rivers and streams may become warmer and drought frequency and severity may increase. Such changes may increase autotrophy in rivers with broad implications for carbon cycling and water quality in aquatic ecosystems.

Connecticut, Massachusetts, New Hampshire, Vermont↗
USGS2014

Empirical models for predicting volumes of sediment deposited by debris flows and sediment-laden floods in the transverse ranges of southern California

Debris flows and sediment-laden floods in the Transverse Ranges of southern California pose severe hazards to nearby communities and infrastructure. Frequent wildfires denude hillslopes and increase the likelihood of these hazardous events. Debris-retention basins protect communities and infrastructure from the impacts of debris flows and sediment-laden floods and also provide critical data for volumes of sediment deposited at watershed outlets. In this study, we supplement existing data for the volumes of sediment deposited at watershed outlets with newly acquired data to develop new empirical models for predicting volumes of sediment produced by watersheds located in the Transverse Ranges of southern California. The sediment volume data represent a broad sample of conditions found in Ventura, Los Angeles and San Bernardino Counties, California. The measured volumes of sediment, watershed morphology, distributions of burn severity within each watershed, the time since the most recent fire, triggering storm rainfall conditions, and engineering soil properties were analyzed using multiple linear regressions to develop two models. A “long-term model” was developed for predicting volumes of sediment deposited by both debris flows and floods at various times since the most recent fire from a database of volumes of sediment deposited by a combination of debris flows and sediment-laden floods with no time limit since the most recent fire (n = 344). A subset of this database was used to develop an “emergency assessment model” for predicting volumes of sediment deposited by debris flows within two years of a fire (n = 92). Prior to developing the models, 32 volumes of sediment, and related parameters for watershed morphology, burn severity and rainfall conditions were retained to independently validate the long-term model. Ten of these volumes of sediment were deposited by debris flows within two years of a fire and were used to validate the emergency assessment model. The models were validated by comparing predicted and measured volumes of sediment. These validations were also performed for previously developed models and identify that the models developed here best predict volumes of sediment for burned watersheds in comparison to previously developed models.

California↗
USGS1994

Rainfall, streamflow, and water-quality data for five small watersheds, Nashville, Tennessee, 1990-92

Rainfall, streamflow, and water-quality data were collected during storm conditions at five urban watersheds in Nashville, Tennessee. These data can be used to build a database for developing predictive models of the relations between stormwater quality and land use, storm characteristics, and seasonal variations. The primary land use and mix of land uses was different for each watershed. Stormwater samples were collected during three storms at each watershed and analyzed for selected volatile, acidic and base/neutral organic compounds; organic pesticides; trace metals; conventional pollutants; and several physical properties. Storm loads were computed for all constituents and properties with event mean concentration above the minimum reporting level. None of the samples contained acidic organic compounds at concentrations above the minimum reporting levels. Several constituents in each of the other categories, however, were present at concentrations above this level. For 21 of these, water-quality criteria have been promulgated by the State of Tennessee. For only 8 of the 21 did the value exceed the most restrictive of the criteria: pyrene, dieldrin, and mercury concentrations and counts of fecal * coliform exceeded the criteria for recreational use, copper and zinc concentrations and p value exceeded the criteria for fish and aquatic life, and lead concentrations exceeded for domestic supply.

Tennessee↗
USGS2022

Assessing the impact of chloride deicer application in the Siskiyou Pass, southern Oregon

Chloride deicers have been applied by the Oregon Department of Transportation (ODOT) to Interstate Route 5 (I–5) from the Oregon-California border north to mile marker 10 for several years in the high-elevation area known as the Siskiyou Pass. Magnesium chloride (MgCl 2 ) and sodium chloride (NaCl) are applied to keep the interstate highway safe for drivers and allow for efficient transport of goods and people through adverse weather conditions, particularly snow and ice. The U.S. Geological Survey entered into a cooperative agreement with ODOT to research the effects of chloride deicers in the Carter and Wall Creek watersheds that drain the vicinity of the Siskiyou Pass. The Stochastic Empirical Loading and Dilution Model (SELDM) was used to estimate combinations of prestorm-streamflow, stormflow, highway-runoff, and event mean constituent concentrations (EMCs), as well as stormwater-constituent loads at sites of interest. The study evaluated the effects of roadway application of chloride deicers on downstream and highway-runoff conditions (particularly EMCs), exceedance rates of criterion maximum concentrations, and concurrent runoff loads of stormwater constituents from a site of interest. SELDM was also used to evaluate the efficiency of hydrograph extension best management practices to reduce peak constituent concentrations. Several SELDM scenarios were developed as sensitivity analyses to evaluate the model benefit of collecting specific local sets of data, such as streamflow, precipitation, highway-runoff and riverine water-quality samples, and volumetric runoff coefficient statistics. Results of the study showed that for SELDM modeling in the Siskiyou Pass area, (1) the inclusion of local streamflow data is important for obtaining accurate downstream EMCs, (2) the inclusion of precipitation data is important for highway and concurrent runoff load calculations, and (3) water-quality constituent EMC data from highway runoff and upstream stormflows are the most important data to collect for highway runoff and upstream water-quality constituent concentration statistics.

Oregon↗
USGS2010

Surface-water quantity and quality, aquatic biology, stream geomorphology, and groundwater-flow simulation for National Guard Training Center at Fort Indiantown Gap, Pennsylvania, 2002-05

Base-line and long-term monitoring of water resources of the National Guard Training Center at Fort Indiantown Gap in south-central Pennsylvania began in 2002. Results of continuous monitoring of streamflow and turbidity and monthly and stormflow water-quality samples from two continuous-record long-term stream sites, periodic collection of water-quality samples from five miscellaneous stream sites, and annual collection of biological data from 2002 to 2005 at 27 sites are discussed. In addition, results from a stream-geomorphic analysis and classification and a regional groundwater-flow model are included. Streamflow at the facility was above normal for the 2003 through 2005 water years and extremely high-flow events occurred in 2003 and in 2004. Water-quality samples were analyzed for nutrients, sediments, metals, major ions, pesticides, volatile and semi-volatile organic compounds, and explosives. Results indicated no exceedances for any constituent (except iron) above the primary and secondary drinking-water standards or health-advisory levels set by the U.S. Environmental Protection Agency. Iron concentrations were naturally elevated in the groundwater within the watershed because of bedrock lithology. The majority of the constituents were at or below the method detection limit. Sediment loads were dominated by precipitation due to the remnants of Hurricane Ivan in September 2004. More than 60 percent of the sediment load measured during the entire study was transported past the streamgage in just 2 days during that event. Habitat and aquatic-invertebrate data were collected in the summers of 2002-05, and fish data were collected in 2004. Although 2002 was a drought year, 2003-05 were above-normal flow years. Results indicated a wide diversity in invertebrates, good numbers of taxa (distinct organisms), and on the basis of a combination of metrics, the majority of the 27 sites indicated no or slight impairment. Fish-metric data from 25 sites indicated results similar to the invertebrate data. Stream classification based on evolution of the stream channels indicates about 94 percent of the channels were considered to be in equilibrium (type B or C channels), neither aggrading nor eroding. A regional, uncalibrated groundwater-flow model indicated the surface-water and groundwater-flow divides coincided. Because of folding of rock layers, groundwater was under confined conditions and nearly all the water leaves the facility via the streams.

Scientific Investigations Report↗
USGS2016

Atmospheric inputs of organic matter to a forested watershed: Variations from storm to storm over the seasons

The objectives of this study were to determine the quantity and chemical composition of precipitation inputs of dissolved organic carbon (DOC) to a forested watershed; and to characterize the associated temporal variability. We sampled most precipitation that occurred from May 2012 through August 2013 at the Susquehanna Shale Hills Critical Zone Observatory (Pennsylvania, USA). Sub-event precipitation samples (159) were collected sequentially during 90 events; covering various types of synoptic meteorological conditions in all climatic seasons. Precipitation DOC concentrations and rates of wet atmospheric DOC deposition were highly variable from storm to storm, ranging from 0.3 to 5.6 mg C L −1 and from 0.5 to 32.8 mg C m −2 h −1 , respectively. Seasonally, storms in spring and summer had higher concentrations of DOC and more optically active organic matter than in winter. Higher DOC concentrations resulted from weather types that favor air advection, where cold frontal systems, on average, delivered more than warm/stationary fronts and northeasters. A mixed modeling statistical approach revealed that factors related to storm properties, emission sources, and to the chemical composition of the atmosphere could explain more than 60% of the storm to storm variability in DOC concentrations. This study provided observations on changes in dissolved organic matter that can be useful in modeling of atmospheric oxidative chemistry, exploring relationships between organics and other elements of precipitation chemistry, and in considering temporal changes in ecosystem nutrient balances and microbial activity.

Atmospheric Environment↗
USGS2011

Water-quality characteristics of urban storm runoff at selected sites in East Baton Rouge Parish, Louisiana, February 2006 through November 2009

Water samples were collected at three watersheds in East Baton Rouge Parish, Louisiana, during February 2006 through November 2009 for continued evaluation of urban storm runoff. The watersheds represented land uses characterized predominantly as established commercial, industrial, and residential. The following water-quality data are reported: physical and chemical-related properties, fecal coliform, nutrients, trace elements, and organic compounds. Results of water-quality analyses enabled calculation of event-mean concentrations and estimated annual contaminant loads and yields of storm runoff from nonpoint sources for 12 water-quality properties and constituents. Lead met or exceeded the U.S. Environmental Protection Agency Maximum Contaminant Level of 15 micrograms per liter for drinking water standards in 4 of 14 samples. Low level concentrations of mercury were detected in all 14 samples, and half were two to four times above the reporting limit of 0.02 micrograms per liter. The average dissolved phosphorus concentrations from each land use were two to four times the U.S. Environmental Protection Agency criterion of 0.05 milligrams per liter. Diazinon was detected in one sample at a concentration of 0.2 micrograms per liter. In the residential watershed, the largest at 216 acres, contaminant loads for 5 of the 12 water-quality properties and constituents were highest, with 4 of these being nutrients. The industrial watershed, 97 acres, had the highest contaminant loads for 6 of the 12 water-quality properties and constituents with 3 of these being metals, which is indicative of the type of land use. Zinc had the highest metal load (155 pounds per year) in the industrial watershed, compared to 36 pounds per year in the residential watershed, and 32 pounds per year in the established commercial watershed. The industrial watershed had the highest yields for 8 of the 12 water-quality properties and constituents, whereas the established commercial watershed had the lowest yield for 5 of the 12. Lower yields from the established commercial and residential watersheds could be from Best Management Practices in place that help control increased runoff from impervious areas and land development. Metal yields from all the watersheds were less than 1 pound per acre per year, except for the zinc from the industrial watershed, which was 2 pounds per acre per year. Nutrient yields in the established commercial watershed were lowest for total nitrogen, ammonia plus organic nitrogen (Kjeldahl nitrogen), and dissolved phosphorus.

Louisiana↗
USGS2017

Synoptic sampling and principal components analysis to identify sources of water and metals to an acid mine drainage stream

Combining the synoptic mass balance approach with principal components analysis (PCA) can be an effective method for discretising the chemistry of inflows and source areas in watersheds where contamination is diffuse in nature and/or complicated by groundwater interactions. This paper presents a field-scale study in which synoptic sampling and PCA are employed in a mineralized watershed (Lion Creek, Colorado, USA) under low flow conditions to (i) quantify the impacts of mining activity on stream water quality; (ii) quantify the spatial pattern of constituent loading; and (iii) identify inflow sources most responsible for observed changes in stream chemistry and constituent loading. Several of the constituents investigated (Al, Cd, Cu, Fe, Mn, Zn) fail to meet chronic aquatic life standards along most of the study reach. The spatial pattern of constituent loading suggests four primary sources of contamination under low flow conditions. Three of these sources are associated with acidic (pH <3.1) seeps that enter along the left bank of Lion Creek. Investigation of inflow water (trace metal and major ion) chemistry using PCA suggests a hydraulic connection between many of the left bank inflows and mine water in the Minnesota Mine shaft located to the north-east of the river channel. In addition, water chemistry data during a rainfall-runoff event suggests the spatial pattern of constituent loading may be modified during rainfall due to dissolution of efflorescent salts or erosion of streamside tailings. These data point to the complexity of contaminant mobilisation processes and constituent loading in mining-affected watersheds but the combined synoptic sampling and PCA approach enables a conceptual model of contaminant dynamics to be developed to inform remediation.

Environmental Science and Pollution Research↗
USGS2018

Effects of water level and climate on the hydrodynamics and water quality of Anvil Lake, Wisconsin, a shallow seepage lake

Interannual differences in the water quality of Anvil Lake, Wisconsin, were examined to determine how water level and climate affect the hydrodynamics and trophic state of shallow lakes, and their importance compared to anthropogenic changes in the watershed. Anvil Lake is a relatively pristine seepage lake with hydrology dominated by precipitation, evaporation, and groundwater exchange enabling the typically subtle effects of water level and climate to be evaluated. Groundwater and hydrodynamic models were used to describe lake water and phosphorus budgets and how its hydrodynamics are affected by water level and air temperature. Decreases in water level are expected to cause Anvil Lake and other shallow lakes to stratify fewer days, and have warmer bottom temperatures and more deep-mixing events. Increasing air temperatures should cause these lakes to have shorter ice cover, longer summer stratification periods, and warmer bottom temperatures. How water level affects water quality depends on how nutrient loading and lake volume vary: during drier, low-water years, lakes with large interannual changes in loading should have better water quality, whereas lakes with small changes in loading should degrade slightly. Anthropogenic changes in Anvil Lake's watershed over the past ∼100 yr were about 1.5 times the effects of changes in water level when levels were low, but the effects were similar when levels were high. Climate warming is expected to increase productivity in shallow lakes because warmer air temperatures will likely increase bottom temperatures increasing sediment phosphorus release and deep-mixing events enabling this phosphorus to reach the epilimnion.

Wisconsin↗
USGS2015

Comparative analysis of riverscape genetic structure in rare, threatened and common freshwater mussels

Freshwater mussels (Bivalvia: Unionoida) are highly imperiled with many species on the verge of local extirpation or global extinction. This study investigates patterns of genetic structure and diversity in six species of freshwater mussels in the central Great Lakes region of Ontario, Canada. These species vary in their conservation status (endangered to not considered at risk), life history strategy, and dispersal capabilities. Evidence of historical genetic connectivity within rivers was ubiquitous across species and may reflect dispersal abilities of host fish. There was little to no signature of recent disturbance events or bottlenecks, even in endangered species, likely as a function of mussel longevity and historical population sizes (i.e., insufficient time for genetic drift to be detectable). Genetic structure was largely at the watershed scale suggesting that population augmentation via translocation within rivers may be a useful conservation tool if needed, while minimizing genetic risks to recipient sites. Recent interest in population augmentation via translocation and propagation may rely on these results to inform management of unionids in the Great Lakes region.

Ontario↗
USGS2026

Extreme Potomac floods at Washington D.C. during the past 500 years

Washington D.C. faces one of the highest 100-year flood risks of any major city along the U.S. East Coast. In addition to storm-surge inundation during hurricanes and nor'easters, water-level observations for Washington are strongly skewed by major floods on the Potomac River. Using geologic and historic records we find new evidence for ice-jam flooding at Georgetown during the Little Ice Age, as recently as 1784, that was up to ∼2x the magnitude of the largest events of the past hundred years (1936, 1942). Over the 19th century (a) human modifications to the Potomac estuary as well as (b) increasingly heavy rainfall and (c) land-clearance in the watershed may have contributed to increasingly frequent large floods at Washington. Early surveys of the U.S. Capitol Building and other local landmarks also suggest sea level on the Potomac estuary at Washington has risen by upwards of 0.7 m (2.2 ft) since the 1790s.

Maryland, Virginia↗
USGS2026

Effects of wildfire on soil hydraulic properties in the western Oregon Cascades

Wildfires can substantially impact the hydrology of forested watersheds, increasing the risk of hydrologic hazards such as flash floods and debris flows. Soil hydraulic properties related to infiltration are a key control in determining the timing and magnitude of these hydrogeomorphic events. In our study, we collected 445 soil cores from burned (216 cores) and unburned (229 cores) reference catchments and analyzed them for soil hydraulic properties 10 months after the 2022 Cedar Creek Fire in Oregon, USA. We observed significantly greater field-saturated hydraulic conductivity ( K fs ), sorptivity ( S ), and wetting front potential ( Ψ f ) in burned soils relative to unburned soils, with median ratios of 5.7, 4.4, and 5.0, respectively. Among low-, moderate-, and high burn severity groups, soil hydraulic properties were not statistically different. Reductions in median soil bulk density with increasing burn severity suggested an expansion of pore sizes, which may have been partially responsible for increasing K fs and S . Additionally, in some burned soil samples, the increase in soil hydraulic properties may have been partially related to a concurrent reduction in “natural background” water repellency that is characteristic of dry, unburned soils in the Western Cascades. We observed no evidence of spatial autocorrelation in K fs using semivariogram analysis. Principal component analysis paired with a k- means cluster analysis suggested that soil physical properties explained variations in soil hydraulic properties better than landscape attributes. Although there is a lack of regional results for comparison, our results trend in the opposite direction from drier, lower net primary productivity regions that are typically studied for post-wildfire soil hydraulic properties.

Oregon↗
USGS2002

Potential effects of structural controls and street sweeping on stormwater loads to the lower Charles River, Massachusetts

The water quality of the lower Charles River is periodically impaired by combined sewer overflows (CSOs) and non-CSO stormwater runoff. This study examined the potential non-CSO load reductions of suspended solids, fecal coliform bacteria, total phosphorus, and total lead that could reasonably be achieved by implementation of stormwater best management practices, including both structural controls and systematic street sweeping. Structural controls were grouped by major physical or chemical process; these included infiltration-filtration (physical separation), biofiltration-bioretention (biological mechanisms), or detention-retention (physical settling). For each of these categories, upper and lower quartiles, median, and average removal efficiencies were compiled from three national databases of structural control performance. Removal efficiencies obtained indicated a wide range of performance. Removal was generally greatest for infiltration-filtration controls and suspended solids, and least for biofiltration-bioretention controls and fecal coliform bacteria. Street sweeping has received renewed interest as a water-quality control practice because of reported improvements in sweeper technology and the recognition that opportunities for implementing structural controls are limited in highly urbanized areas. The Stormwater Management Model that was developed by the U.S. Geological Survey for the lower Charles River Watershed was modified to simulate the effects of street sweeping in a single-family land-use basin. Constituent buildup and washoff variable values were calibrated to observed annual and storm-event loads. Once calibrated, the street sweeping model was applied to various permutations of four sweeper efficiencies and six sweeping frequencies that ranged from every day to once every 30 days. Reduction of constituent loads to the lower Charles River by the combined hypothetical practices of structural controls and street sweeping was estimated for a range of removal efficiencies because of their inherent variability and uncertainty. This range of efficiencies, with upper and lower estimates, provides reasonable bounds on the load that could be removed by the practices examined. The upper estimated load reduction from combined street sweeping and structural controls, as a percentage of the total non-CSO load entering the lower Charles River downstream of Watertown Dam, was 44 percent for suspended solids, 34 percent for total lead, 14 percent for total phosphorus, and 17 percent for fecal coliform bacteria. The lower estimated load reduction from combined street sweeping and structural controls from non-CSO sources downstream of Watertown Dam, was 14 percent for suspended solids, 11 percent for total lead, 4.9 percent for total phosphorus, and 7.5 percent for fecal coliform bacteria. Load reductions by these combined management practices can be a small as 1.4 percent for total phosphorus to about 4 percent for the other constituents if the total load above Watertown Dam is added to the load from below the dam. Although the reductions in stormwater loads to the lower Charles River from the control practices examined appear to be minor, these practices would likely provide water-quality benefits to portions of the river during those times that they are most impaired-during and immediately after storms. It should also be recognized that only direct measurements of changes in stormwater loads before and after implementation of control practices can provide definitive evidence of the beneficial effects of these practices on water-quality conditions in the lower Charles River.

Massachusetts↗
USGS2011

Spatial variation in transient water table responses: Differences between an upper and lower hillslope zone

To better understand storage-runoff dynamics, transient groundwater responses were examined in one of the steep watersheds in British Columbia's coastal mountains. Streamflow and piezometric data were collected for 1year to determine the spatial and temporal relations between transient groundwater levels and discharge. Correlations between piezometer responses and lag-time analysis were used to identify and better understand runoff generation mechanisms in this watershed. Results showed a large spatial and temporal variation in transient water table dynamics and indicated that two distinct zones existed: a lower hillslope zone and an upslope zone. Each zone was characterized by very different water table responses. The upper hillslope was disconnected from the stream for the majority of time, suggesting that during most events, it does not directly contribute to streamflow. Piezometers in the lower hillslope zone showed hydrologically limited responses, suggesting rapid subsurface flow, likely through the many macropores and soil pipes. The lag time between peak streamflow and peak groundwater level decreased with increasing antecedent moisture conditions and was more variable for piezometers further away from the stream than for piezometers close to the stream. The study results indicate that a single storage-runoff model is not appropriate for this steep watershed and that a two- or three-compartment model would be more suitable. ?? 2011 John Wiley & Sons, Ltd.

Hydrological Processes↗
USGS2002

Analysis of δ15N and δ18O to differentiate NO3− sources in runoff at two watersheds in the Catskill Mountains of New York

To quantify the movement of atmospheric nitrogen deposition through two forested watersheds in the Catskill Mountains of New York, dual‐isotope analysis (δ 15 N and δ 18 O) was used to differentiate NO 3 − derived from precipitation from NO 3 − derived by microbial nitrification and to quantify the contributions of these sources to NO 3 − in drainage waters. Samples of stream water, soil water, precipitation, snowmelt, and O‐horizon soil were collected during the March and April snowmelt period of 1994 and throughout an 18‐month period from August 1995 through February 1997. The mean δ 18 O‐NO 3 − value of precipitation was +50.5‰, whereas the mean values for stream water and soil water were +17.7‰ and +23.6‰, respectively. The mean δ 15 N‐NO 3 − of precipitation was −0.2‰, that of soil water was +1.4‰, and that of stream water was +2.3‰; these values showed greater overlap among the three different waters than did the δ 18 O‐NO 3 − values, indicating that δ 15 N‐NO 3 − was not as useful for source separation. Soil water δ 18 O‐NO 3 − values decreased, and δ 15 N‐NO 3 − values increased, from the O to the B and C horizons, but most of the differences among horizons were not statistically significant. Nitrate derived by nitrification in incubated soil samples had a wide range of δ 15 N‐NO 3 − values, from +1.5‰ to +16.1‰, whereas δ 18 O‐NO 3 − values ranged more narrowly, from +13.2‰ to +16.0‰. Values of δ 18 O‐NO 3 − indicated that NO 3 − in stream water is mainly derived from nitrification. Only during a high‐flow event that exceeded the annual flood was precipitation a major contributor to stream water NO 3 − . Values of δ 18 O‐NO 3 − and δ 15 N‐NO 3 − changed at differing rates as NO 3 − cycled through these watersheds because δ 18 O‐NO 3 − values change sharply through the incorporation of oxygen from ambient water and gas during nitrification, whereas δ 15 N‐NO 3 − values change only incrementally through fractionation during biocycling processes. The results of this study show that most NO 3 − is first cycled through the biota and nitrified before entering the stream.

Water Resources Research↗