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USGS2012

Effects of urban development on stream ecosystems in nine metropolitan study areas across the United States

Urban development is an important agent of environmental change in the United States. The urban footprint on the American landscape has expanded during a century and a half of almost continuous development. Eighty percent of Americans now live in metropolitan areas, and the advantages and challenges of living in these developed areas—convenience, congestion, employment, pollution—are part of the day-to-day realities of most Americans. Nowhere are the environmental changes associated with urban development more evident than in urban streams. Contaminants, habitat destruction, and increasing streamflow flashiness resulting from urban development have been associated with the disruption of biological communities, particularly the loss of sensitive aquatic species. Every stream is connected downstream to larger water bodies, including rivers, reservoirs, and ultimately coastal waters. Inputs of chemical contaminants or sediments at any point along the stream can cause degradation downstream with adverse effects on biological communities and on economically valuable resources, such as fisheries and tourism. In response to general concerns about the degradation of urban streams, the U.S. Geological Survey (USGS) conducted a national-scale, scientific investigation of the effects of urban development on stream ecosystems. Nine metropolitan study areas of the United States were selected—Portland, Oregon; Salt Lake City, Utah; Birmingham, Alabama; Atlanta, Georgia; Raleigh, North Carolina; Boston, Massachusetts; Denver, Colorado; Dallas, Texas; and Milwaukee, Wisconsin. The studies were conducted in Salt Lake City, Birmingham, and Boston in 1999–2000; in Atlanta, Raleigh, and Denver in 2002–2003; and in Portland, Dallas, and Milwaukee in 2003–2004. The comprehensive investigation of all nine studies focused on three broad questions of interest to decision makers: What are the primary effects of urban development on stream ecosystems? How do the effects of urban development on stream ecosystems vary regionally across the country? Which urban-related stressors are most closely linked to biological community degradation, and how can multiple stressors be managed to protect stream health as a watershed becomes increasingly urbanized?

Alabama;Colorado;Georgia;Massachusetts;North Carol↗

USGS2025

Ecosystems

The Fifth National Climate Assessment updates the evidence regarding how climate change influences ecosystems, biological diversity, and the implications for changes to critical ecosystem services—as noted in the key messages above (McElwee et al., 2023). Large-scale transformational changes to ecosystems are occurring, including—but not limited to—land-use conversion, hydrological alteration, and fire regimes. Implications of such transformational change include ecosystem capacity to maintain biological diversity and ecosystem services, impacting recreational opportunities (e.g., hunting and fishing, birding, ecotourism) and agriculture production (McElwee et al., 2023). A central tenet of the Fifth National Climate Assessment regarding ecosystems was the shifts to alternative states and how the Resist-Accept-Direct (RAD) framework may guide the adaptive management of ecosystems moving forward (Lynch et al., 2022). Nebraska is in the northern Great Plains, where extremes in climate and resulting ecosystem processes are experienced (Knapp et al., 2023). Pressures on ecosystems to provide essential services, including healthy soil and water to benefit humans and animals, will inevitably impact economic development, urban and rural communities, and fish and wildlife populations as climate change continues (Knapp et al., 2023). All ecosystems will be impacted in Nebraska, but aquatic systems—wetlands, aquifers, lakes, streams, and rivers—may be most impacted, given the scarcity of water as human demand (i.e., agriculture and a growing population) persists and increases (Bathke et al., 2014). Major knowledge gaps remain regarding how fish and wildlife populations will persist in changing environments. Past changes, including large-scale land conversion, water delivery systems, and water storage (construction of reservoirs), suggest that some species can adapt to novel environments and shift distributions. However, many more species may be maladapted to the expected changes in climate. Species may be unable to move to suitable habitats, and biological constraints under rapidly changing conditions may impede adaptation— resulting in extirpation and potential extinction. Further, changing conditions open multiple pathways for invasive species and novel diseases, impacting native fish populations, wildlife populations, and human health.

Nebraska↗

USGS2010

Microbial degradation of plant leachate alters lignin phenols and trihalomethane precursors

Although the importance of vascular plant-derived dissolved organic carbon (DOC) in freshwater systems has been studied, the role of leached DOC as precursors of disinfection byproducts (DBPs) during drinking water treatment is not well known. Here we measured the propensity of leachates from four crops and four aquatic macrophytes to form trihalomethanes (THMs)—a regulated class of DBPs—before and after 21 d of microbial degradation. We also measured lignin phenol content and specific UV absorbance (SUVA 254 ) to test the assumption that aromatic compounds from vascular plants are resistant to microbial degradation and readily form DBPs. Leaching solubilized 9 to 26% of total plant carbon, which formed 1.93 to 6.72 mmol THM mol C -1 However, leachate DOC concentrations decreased by 85 to 92% over the 21-d incubation, with a concomitant decrease of 67 to 92% in total THM formation potential. Carbon-normalized THM yields in the residual DOC pool increased by 2.5 times on average, consistent with the preferential uptake of nonprecursor material. Lignin phenol concentrations decreased by 64 to 96% over 21 d, but a lack of correlation between lignin content and THM yields or SUVA 254 suggested that lignin-derived compounds are not the source of increased THM precursor yields in the residual DOC pool. Our results indicate that microbial carbon utilization alters THM precursors in ecosystems with direct plant leaching, but more work is needed to identify the specific dissolved organic matter components with a greater propensity to form DBPs and affect watershed management, drinking water quality, and human health.

Journal of Environmental Quality↗

USGS2021

Occurrence, fate, and transport of aerially applied herbicides to control invasive buffelgrass within Saguaro National Park Rincon Mountain District, Arizona, 2015–18

The spread of the invasive and fire-adapted buffelgrass ( Cenchrus ciliaris L.) threatens desert ecosystems by competing for resources, increasing fuel loads, and creating wildfire connectivity. The Rincon Mountain District of Saguaro National Park addressed this natural resource threat with the use of glyphosate-based herbicides (GBHs). In 2010, the Rincon Mountain District initiated an aerial restoration plan to control dense buffelgrass patches in remote areas and implemented a trial project to evaluate the effects of aerial restoration techniques that included the helicopter application of GBHs. In 2014, more than 250 acres of buffelgrass in the Rincon Mountain District were treated with the aerial application of GBHs. This widespread aerial application of GBHs continued through 2018, but the potential transport and effects to aquatic ecosystems were unknown. In 2015–18, the U.S. Geological Survey, in cooperation with the National Park Service, studied the occurrence, distribution, fate, and transport of glyphosate in surface water and sediments derived from areas that were treated during past and current aerial herbicide applications. Three watersheds, treated with different regimens of GBHs, were sampled for glyphosate and the primary metabolite of glyphosate, aminomethylphosphonic acid (AMPA), during various hydrologic flow conditions. Water and aquatic sediment were collected from three watersheds, each in a different stage of application during the U.S. Geological Survey study. The unnamed watershed above the Loma Verde Trailhead referred to by the National Park Service as “Loma Verde canyon” had received no aerial treatment since 2014, whereas the Box Canyon watershed was aerially treated every year beginning in 2014. The Madrona Canyon watershed was first sprayed in 2016 and aerial application continued once a year though the entirety of the study. In addition, terrestrial soil samples were sampled from areas sprayed to understand dissipation rates and herbicide transport via sediments washing away during rainfall runoff. The concentrations present in water and sediment samples were compared to ecological benchmarks and characterized within the context of the environmental conditions of the park setting. Of the 48 water samples collected and analyzed for glyphosate and AMPA, 10.4 percent and 14.6 percent were detected above the laboratory minimum detection limit, respectively. Mean water concentrations, calculated using specific statistical methods for non-detects, were equal to the laboratory minimum detection limit of 0.02 microgram per liter for samples collected in all the watersheds. In aquatic sediments, glyphosate and AMPA were detected in 10.7 and 25.0 percent of the samples, whereas 89.5 and 100 percent of the terrestrial soil samples had detections for glyphosate and AMPA, respectively. Mean aquatic sediment concentrations were 1.13 and 4.42 micrograms per kilogram (μg/kg) for glyphosate and AMPA, respectively. Mean terrestrial soil concentrations were orders of magnitude greater than water and aquatic sediment with concentrations of 678 μg/kg for AMPA and 1,240 μg/kg for glyphosate. Hours after glyphosate-based herbicide was applied, the concentrations of glyphosate and AMPA were present in terrestrial soil samples near or above the laboratory maximum detection limit of 5,000 μg/kg. The Box Canyon watershed was the most intensively treated watershed in terms of total land area treated, total amount of GBH applied, and number of years treated. The frequent and large volume of treatment resulted in the highest number of detections of glyphosate and AMPA in water (3 and 7 detections, respectively) and in aquatic sediment (2 and 6 detections, respectively) samples. In comparison, the other two watersheds had two or fewer detections for glyphosate and AMPA in water and aquatic sediment. Glyphosate detected in pools was associated with increased rainfall closer in time to the last herbicide treatment. Glyphosate and AMPA concentration ratios above one, along with stable-isotope and tritium results, indicated that runoff processes were the primary transport mechanism for the two compounds when found in streams and pools rather than subsurface recharge or deeper flow paths. One pool in a small tributary of Box Canyon consistently had detections of glyphosate and AMPA in aquatic sediments, but these frequent concentrations were likely related to the intensive application upstream, near the steep terrain above the head of the channel that supplies the downstream pool. Intense flows during summer rainfall events move treated sediments into this channel where vegetation and the incised bedrock banks of the pool retained those sediments and ultimately led to frequent detections of both compounds. Isotope results in most of the pools and tinajas indicated that the water source had residence time representative of recently recharged waters, on the order of years. No water concentrations exceeded published criteria for human health or aquatic life. Median and maximum glyphosate and AMPA water concentrations were lower than those reported in other national assessments, but maximum concentrations observed in individual runoff samples were higher than median concentrations measured in the national assessments. A similar finding was observed with aquatic sediment concentrations measured in the Rincon Mountain District. Results from the study were compared and assessed in the context of other studies examining GBHs and their effects on amphibians, fish, and macroinvertebrates. This comparison was used to generalize the potential risk to aquatic species similar to those species in the Rincon Mountain District. Concentrations of published effect levels were several orders of magnitude greater than the highest concentration detected in water at the Rincon Mountain District. Most published studies evaluate acute and chronic toxicity for glyphosate and GBHs, and these criteria may not be representative of environmental conditions in the Rincon Mountain District. The classic lethal dose studies conducted in a controlled laboratory setting may not be suitable for comparison to the longer, variable, low-dose exposure conditions in the pools and tinajas in the Rincon Mountain District. However, this study determined that the fate of GBHs transported from treated areas to potential aquatic habitat was highly variable in occurrence, timing, and concentrations. This variability in glyphosate concentrations was too high, and the potential exposure was determined to be far too complex to directly compare with the results from controlled studies. This study provides the first information collected on GBHs used to control invasive buffelgrass in a remote, mountainous, and semiarid setting. The information about the transport and fate of herbicide application near aquatic habitat will help to inform managers about the broader ecosystem implications and provide useful information to other agencies implementing buffelgrass remediation strategies near aquatic habitat.

Arizona↗

USGS2025

A 10-year continuous daily simulation of chloride flux from a suburban watershed in Fairfax County, Virginia, USA

Increasing levels of chloride in surface water are associated with detrimental effects on water quality, aquatic ecosystems, infrastructure, and human health. Numerous mass-balance studies have inferred watershed transport processes by interpreting chloride inputs and outputs, but few represent internal dynamics explicitly. We constructed a coupled water/chloride mass balance model to gain insights into storage, residence time, and transport processes in a 10-km 2 urban watershed. The model, which operates over a 10-year period at a daily time scale, represents storage in a dynamic soil-moisture reservoir, quick-flow runoff from storm events, and slow-flow runoff that sustains streamflow in dry weather. The calibrated model accurately represented (a)the observed transition from a streamflow enrichment regime in cold months to a dilution regime in warmer months, (b) the observed tendency for late-summer concentrations to be higher after winters with heavy snowfall, and (c) a period-of-record downward trend in chloride concentration likely associated with a downward trend in annual snowfall. Estimated chloride inputs averaged 195 metric tons per year, while the average output was 270 metric tons per year. In contrast, estimated storage was only 107 metric tons. The estimated mean residence time in groundwater was 1.27 years. This short residence time indicates that efforts to reduce inputs will manifest as decreased concentrations in streamflow on a management-relevant time scale of several years. The coupled mass balance model yielded insights into internal watershed dynamics that would not be possible from simple input/output analysis; such models can be useful tools for gaining insight into small watershed hydrology and pollutant transport.

Virginia↗

USGS2010

The potential influence of changing climate on the persistence of salmonids of the inland west

The Earth's climate warmed steadily during the 20th century, and mean annual air temperatures are estimated to have increased by 0.6°C (Intergovernmental Panel on Climate Change, 2007). Although many cycles of warming and cooling have occurred in the past, the most recent warming period is unique in its rate and magnitude of change (Siegenthaler and others, 2005) and in its association with anthropogenic emissions of greenhouse gases (Intergovernmental Panel on Climate Change , 2007). The climate in the western United States warmed in concert with the global trend but at an accelerated rate (+0.8°C during the 20th century; Saunders and others, 2008). The region could also prove especially sensitive to future changes because the relatively small human population is growing rapidly, as are demands on limited water supplies. Regional hydrological patterns are dominated by seasonal snow accumulation at upper elevations. Most of the region is relatively dry, and both terrestrial and aquatic ecosystems are strongly constrained b y water availability (Barnett and others, 2008; Brown and others, 2008). Stream environments are dynamic and climatically extreme, and salmonid fishes are the dominant elements of the native biodiversity (McPhail and Lindsey, 1986; Waples and others, 2008). Salmonids have broad economic and ecologic importance, but a century of intensive water resource development, nonnative fish stocking, and land use has significantly reduced many populations and several taxa are now protected under the Endangered Species Act (Thurow and others, 1997; Trotter, 2008). Because salmonids require relatively pristine, cold water environments and are often isolated in headwater habitats, members of this group may be especially vulnerable to the effects of a warming climate (Keleher and Rahel, 1996; Rieman and others, 2007; Williams and others, 2009). Warming during the 20th century drove a series of environmental trends that have profound implications for many aspects of salmonid habitat, including disturbance regimes such as wildfire, and unfavorable changes to thermal and hydrologic properties of aquatic systems. Warmer air temperatures have been associated with decreased winter snow accumulations, have accelerated snowmelt, and have advanced the timing of peak runoff by several days to weeks across most of western North America (Stewart and others, 2005; Barnett and others, 2008). Less snow and earlier runoff decrease aquifer recharge, make less water available for groundwater inputs to streams, and are contributing to widespread decreases in summer low flows (Stewart and others, 2005; Rood and others, 2008; Luce and Holden 2009). Interannual variability in stream flow is increasing, as is the persistence of multi-year extreme conditions (McCabe and others, 2004; Pagano and Garen 2005). In many areas of western North America, flood risks have increased in association with warmer temperatures during the 20th century (Hamlet and Lettenmaier, 2005). Streams where midwinter temperatures are near freezing have proven especially sensitive to increased flooding because of associated transitional hydrological patterns (mixtures of rainfall and snowmelt) and propensity for occasional rain-on-snow events to rapidly melt winter snowpack and generate large floods (Hamlet and Lettenmaier, 2005). Stream temperatures in many areas are increasing (Peterson and Kitchell, 2001; Morrison and others, 2002; Bartholow, 2005; Kaushal and others, 2010), due to both air temperature increases and reduced summer flows that make streams more sensitive to warmer air temperatures (Isaak and others, 2010). In recent decades, wildfires have become more common across much of the western United States during periods of more frequent droughts (Westerling and others, 2006; Hoerling and Eischeid, 2007), and local stream temperature can increase in postfire environments (Gresswell, 1999; Dunham and others, 2007). Fire-related temperature increase within streams is commonly a transient phenomenon, lasting only until riparian vegetation has recovered (Gresswell, 1999); however, ongoing climate change could preclude recovery to higher stature, prefire vegetation types in some areas (McKenzie and others, 2004; van Mantgem and Stephenson, 2007), resulting in a loss of critical riparian shading. Additionally, when wildfires occur in steep mountain topographies, the vegetation that stabilize s soils on hillslopes is often killed and landslides become more prevalent (Gresswell, 1999). Landslides int o stream channels form debris flows composed of sediment slurries and dead trees that can scour channels to bedrock and further exacerbate stream heating, delay recovery of riparian areas, or extirpate fish populations (Gresswell, 1999; May and Gresswell, 2003; Dunham and others, 2007). Changes in stream environments will shift habitat distributions, sometimes unpredictably, in both time and space for many salmonid fishes. Water temperature fundamentally influences aquatic ecosystem health because distribution, reproduction, fitness, and survival of ectothermic organisms are inextricably linked to the thermal regime of the environment. Historically, research has focused on defining lethal thermal limits of salmonids (Eaton and others, 1995; Selong and others, 2001; Todd and others, 2008); however, water temperature is known to be important in biological processes at a variety of spatial scales and levels of biological organization (Rahel and Olden, 2008; McCullough and others, 2009). For instance, trout are affected directly by water temperature through feeding, metabolism, and growth rates, and indirectly by factors such as prey availability and species interactions (Wehrly and others, 2007; Rahel and Olden, 2008). Where cold water temperatures currently limit habitat suitability and distributions of some species (for example, at the highest and most northerly distributional extents; Nakano and others, 1996; Coleman and Fausch, 2007), a warming climate may gradually increase the quality and extent of suitable habitat. Over time, previously constrained populations are expected to expand into these new habitats and increase in number. Some evidence suggests this may already be happening in Alaska, where streams in recently deglaciated areas are being colonized by emigrants from nearby salmon and char populations (Milner and others, 2000). Unfortunately, many of the sensitive salmonid species that are often the focus of western managers are unlikely to benefit from future water temperature increases. Warmer stream temperatures will facilitate invasion by nonnative species that are broadly established in downstream areas into upstream areas where they will compete with native species (Rieman and others, 2006; Rahel and Olden, 2008; Fausch and others, 2009). In other cases, warmer stream temperatures will render thermally suitable habitats unsuitable in downstream areas and effect net losses of habitat because upstream distributions are often constrained by streams that are too small or steep (Hari and others, 2006; Isaak and others, 2010). Both scenarios are realistic for fish species like bull trout ( Salvelinus confluentus ) (Rieman and others, 2006; Rieman and others, 2007), the various subspecies of cutthroat trout ( Oncorhynchus clarkii ) (Williams and others, 2009), Gila trout ( Oncorhynchus gilae gilae ) (Kennedy and others, 2008), and Apache trout ( Oncorhynchus gilae apache ) (Rinne and Minckley, 1985; Carmichael and others, 1993). As native species are increasingly confined to smaller and more isolated habitats by a gradually warming climate, the effects of wildfires (whether related to lethal changes in water quality during a fire, channel debris flows, or chronic postfire warming ) could have greater proportional effects on remaining habitats (for example, Brown and others, 2001; Rieman and others, 2007). If these changes were accompanied by additional hydrologic alterations associated with changes to the magnitude, frequency, duration, timing, and rate of change of discharge patterns (Jager and others, 1999; Henderson and others, 2000), populations may begin to lose some of their historic resilience and become ever more susceptible to local extirpations. As dramatic and extensive as climatic and environmental trends are for salmonid habitats, global climate models (GCMs) project that many of these trends will continue and even accelerate until at least the middle of the 21st century (Intergovernmental Panel on Climate Change, 2007). Current projections suggest mean annual air temperatures will increase by an additional 1–3°C, and early indications are that climate trajectory is at the higher end of this range (Pittock, 2006; Raupach and others, 2007). Although predicted changes vary considerably, even the most conservative estimates suggest a warming rate that will be twice that observed during the 20th century. Projections for the midcentury are most certainly due to the effects of greenhouse gases already emitted or predicted in the short term, uncertainties of the effects of longer-term greenhouse gas emissions, short-term climate cycles, and process errors associated with climate models (Cox and Stephenson, 2007). Projections of changes in total precipitation are less certain than those for air temperatures, but most GCMs project relatively small changes in the Northwest, with the exception of slightly drier summer periods (Mote and others, 2008; Karl and others, 2009). In the Southwest, however, significant decreases (such as 15–30 percent ) are projected during most periods of the year, and this area is one of the few for which Intergovernmental Panel on Climate Change (2007) precipitation projections have a high level of certainty (Hoerling and Eischeid, 2007; Karl and others, 2009). Clearly, managers of native salmonids in the wester n United States should consider adjusting management strategies to accommodate a warmer and possibly drier future (Williams and others, 2009). Tools are needed to forecast where important changes may occur and how conservation efforts should be prioritized. In this Open-File Report, we document our initial efforts in this regard for 10 species and subspecies of inland trout and Montana Arctic grayling ( Thymallus arcticus ) across the western United States.

Arizona, California, Colorado, Idaho, Montana, Nev↗

USGS1993

A comparison of water quality criteria for the Great Lakes based on human and wildlife health

Water quality criteria (WQC) can be derived in several ways. The usual techniques involve hazard and risk assessment procedures. For non-persistent, non-biomagnified compounds and elements, WQC are experimentally derived from their acute and chronic toxicity to aquatic organisms. For those persistent chlorinated hydrocarbons (PCHs) that are bioaccumulated and biomagnified, these traditional techniques have not been effective, partly because effects higher in the food web were not considered. Polychlorinated biphenyls (PCBs) are the bioaccumulative synthetic chemicals of primary toxicological significance to the Great Lakes biota which have caused widespread injury to wildlife. In the Laurentian Great Lakes, the primary emphasis of hazard assessments has been on the potential for adverse effects in humans who eat fish. The primary regulatory endpoint of traditional hazard and risk assessments underlying current WQC are the probabilities of additional cancers occurring in the human population. The analysis presented here indicates that this is not adequate to restore sensitive wildlife species that are highly exposed to PCBs, especially those that have suffered serious population declines. Because WQC are legal instruments, the methods of deriving WQC have large implications for remediation, litigation, and damage assessments. Here WQC are derived for six species based on the responses of wildlife in the field or produced by feeding fish to surrogate species, rather than projecting a potential of increased cancer rates in humans. If the most sensitive wildlife species are restored and protected for very sensitive reproductive endpoints, then all components of the ecosystem, including human health, should be more adequately protected. The management of Great Lakes wildlife requires an understanding of the injury and causal relationships to persistent toxic substances.

Journal of Great Lakes Research↗

USGS2015

Predicting the resilience and recovery of aquatic systems: a framework for model evolution within environmental observatories

Maintaining the health of aquatic systems is an essential component of sustainable catchmentmanagement, however, degradation of water quality and aquatic habitat continues to challenge scientistsand policy-makers. To support management and restoration efforts aquatic system models are requiredthat are able to capture the often complex trajectories that these systems display in response to multiplestressors. This paper explores the abilities and limitations of current model approaches in meeting this chal-lenge, and outlines a strategy based on integration of ﬂexible model libraries and data from observationnetworks, within a learning framework, as a means to improve the accuracy and scope of model predictions.The framework is comprised of a data assimilation component that utilizes diverse data streams from sensornetworks, and a second component whereby model structural evolution can occur once the model isassessed against theoretically relevant metrics of system function. Given the scale and transdisciplinarynature of the prediction challenge, network science initiatives are identiﬁed as a means to develop and inte-grate diverse model libraries and workﬂows, and to obtain consensus on diagnostic approaches to modelassessment that can guide model adaptation. We outline how such a framework can help us explore thetheory of how aquatic systems respond to change by bridging bottom-up and top-down lines of enquiry,and, in doing so, also advance the role of prediction in aquatic ecosystem management.

Water Resources Research↗

USGS2025

Estimating indicators of cyanobacterial harmful algal blooms in New York State

Cyanobacteria harmful algal blooms (cyanoHABs) are a global concern for aquatic ecosystem and human health. Limited funding for monitoring programs and inconsistent determination of cyanoHAB occurrence present challenges for identifying commonly effective variables for characterizing cyanoHABs and the development of generalized models. We compiled a combination of water quality measurements, lake morphology, climatology, remote sensing data, and observations of cyanoHAB occurrence across New York State and used this dataset to develop two sets of predictive models. The first model predicted chlorophyll a , a common indicator of algal biomass, and assessed the importance of variables for modeled predictions. The most important variables were then used in a second set of models to classify cyanoHAB occurrence. The irradiance attenuation coefficient ( K d ), which was estimated from Secchi depth measurements, and total phosphorus were the two most important variables for predicting chlorophyll a . The second model examined several variables for their ability to classify cyanoHAB occurrence. Predicted cyanoHAB occurrence based on thresholds of chlorophyll a , K d , or total nitrogen all had moderate agreement and were able to correctly classify approximately 70% of observed cyanoHABs. Our analysis indicated that multiple data types were important for predicting chlorophyll a statewide and that simple widely available water quality parameters could classify cyanoHABs occurrence with reasonable accuracy. Identifying variables that can be monitored with increased frequency and decreased latency to detect cyanoHAB occurrence will better inform water managers and provide valuable additional data for further refining predictive models of the likelihood of cyanoHABs occurrence.

New York↗

USGS2000

A ground electromagnetic survey used to map sulfides and acid sulfate ground waters at the abandoned Cabin Branch Mine, Prince William Forest Park, northern Virginia gold-pyrite belt

INTRODUCTION AND BACKGROUND: Prince William Forest Park is situated at the northeastern end of the Virginia Gold-Pyrite belt northwest of the town of Dumfries, VA. The U. S. Marine Corps Reservation at Quantico borders the park on the west and south, and occupies part of the same watershed. Two abandoned mines are found within the park: the Cabin Branch pyrite mine, a historic source of acid mine drainage, and the Greenwood gold mine, a source of mercury contamination. Both are within the watershed of Quantico Creek (Fig.1). The Cabin Branch mine (also known as the Dumfries mine) lies about 2.4 km northwest of the town of Dumfries. It exploited a 300 meter-long, lens-shaped body of massive sulfide ore hosted by metamorphosed volcanic rocks; during its history over 200,000 tons of ore were extracted and processed locally. The site became part of the National Capitol Region of the National Park Service in 1940 and is currently managed by the National Park Service. In 1995 the National Park Service, in cooperation with the Virginia Department of Mines, Minerals, and Energy reclaimed the Cabin Branch site. The Virginia Gold-Pyrite belt, also known as the central Virginia volcanic-plutonic belt, is host to numerous abandoned metal mines (Pavlides and others, 1982), including the Cabin Branch deposit. The belt itself extends from its northern terminus near Cabin Branch, about 50 km south of Washington, D.C., approximately 175 km to the southwest into central Virginia. It is underlain by metamorphosed volcanic and clastic (non-carbonate) sedimentary rocks, originally deposited approximately 460 million years ago during the Ordovician Period (Horton and others, 1998). Three kinds of deposits are found in the belt: volcanic-associated massive sulfide deposits, low-sulfide quartz-gold vein deposits, and gold placer deposits. The massive sulfide deposits such as Cabin Branch were historically mined for their sulfur, copper, zinc, and lead contents, but also yielded byproduct gold and silver. The environmental impact of massive sulfide deposits can be substantial. These deposits are characterized by high concentrations of heavy-metal sulfide minerals, hosted by silicate rocks. Thus, weathering of these deposits and their mine wastes has the potential to generate heavy-metal laden sulfuric acid that can have negative impacts on aquatic ecosystems. In addition, lead associated with solid mine wastes has the potential for human health impacts through ingestion. The heavy metals that are encountered in these deposits and are most likely to cause environmental impacts include copper, zinc, lead, cadmium, and arsenic. In addition, the weathering of pyrite releases large amounts of iron, and the acid generated attacks the country rocks and causes the release of large amounts of aluminum, which also can severely impact aquatic ecosystems. A reclamation attempt was made at the site in 1995, including construction of storm-water diversion trenches around the abandoned mine area, grading tailings away from the stream bank, addition of pulverized limestone and topsoil, and revegetation. The post-reclamation chemistry of shallow groundwaters (<3 meters deep) shows a neutral pH on the southwestern bank of the stream but pH of 4.1 to 4.5 on the northeastern bank. The dominant ions are Fe2+ and SO42- (Seal, Haffner, Meier, and Pollio, 1999) A ground electromagnetic survey was conducted over the site in 1999 as part of a wider study ( Seal, Haffner, and Meier, 1998a,b, 1999). It was hoped that a 3-D map of the soil conductivity derived from the survey could provide insight into the distribution of the mobilized sulfides present under the ground.

Virginia↗

USGS2003

An introduction to the San Francisco Estuary tidal wetlands restoration series

Restoration of tidal wetlands may provide an important tool for improving ecological health and water management for beneficial uses of the San Francisco Estuary (hereafter “Estuary”). Given the large losses of tidal wetlands from San Francisco Bay and the Sacramento-San Joaquin Delta in the last 150 years, it seems logical to assume that restoring tidal wetlands will have benefits for a variety of aquatic and terrestrial native species that have declined during the same time period. However, many other changes have also occurred in the Estuary concurrent with the declines of native species. Other factors that might be important in species declines include the effects of construction of upstream dams, large and small water diversions within the Sacramento-San Joaquin Delta, agricultural pesticides, trace elements from industrial and agricultural activities, and invasions of alien species. Discussions among researchers, managers, and stakeholders have identified a number of uncertainties regarding the potential benefits of tidal wetland restoration. The articles of the Tidal Wetlands Restoration Series address four major issues of concern. Stated as questions, these are: 1. Will tidal wetland restoration enhance populations of native fishes? 2. Will wetland restoration increase rates of methylation of mercury? 3. Will primary production and other ecological processes in restored tidal wetlands result in net export of organic carbon to adjacent habitats, resulting in enhancement of the food web? Will the carbon produced contribute to the formation of disinfection byproducts when disinfected for use as drinking water? 4. Will restored tidal wetlands provide long-term ecosystem benefits that can be sustained in response to ongoing physical processes, including sedimentation and hydrodynamics? Reducing the uncertainty surrounding these issues is of critical importance because tidal wetland restoration is assumed to be a critical tool for enhancement of native species and ecosystem processes in the Estuary.

California↗

USGS2020

The response of streams to changes in atmospheric deposition of sulfur and nitrogen in the Adirondack Mountains

Acidic deposition is the result of upwind sulfur (S) and nitrogen (N) emissions into the atmosphere from human activities. Environmental impacts from acidic deposition across forested landscapes include acidification of soil and drainage water, depletion of available soil nutrient bases, and impacts to and changes in forest and aquatic species composition and biodiversity. Acidic deposition can mobilize aluminum (Al) from soil-to-soil solution and subsequently to drainage water in forms that can be toxic to aquatic life. When exposed to decreasing levels of acidic deposition, which has been occurring in New York since the late 1970s, some soils and drainage waters have become gradually less acidic. Remaining questions relate to effects on stream resources, anticipated resource recovery under increasingly lower levels of deposition, and the levels of deposition (target loads, TLs) needed to reach a range of stream ecosystem recovery targets. Environmental scientists commonly estimate thresholds of air pollutant emissions and resulting atmospheric deposition at which adverse ecological effects are manifested. This analysis is often done using critical loads (CL) and/or TLs, using approaches that account for the spatial and temporal aspects of acidification and recovery. Exceedance represents the extent to which current levels of acidic deposition exceed the level expected to cause ecological harm. The research reported here is intended to help address S and N deposition TLs and ecosystem recovery of Adirondack streams, a resource that has been less thoroughly investigated than lakes. The overarching goal of this work is to highlight key considerations that will help inform decision-makers and ecosystem managers who are responsible for environmental policy in New York State and beyond. Salient aspects of stream TL modeling are discussed with an aim of informing not only scientists, but also policymakers, ecosystem managers, and nonscientists who are required to make decisions related to the effects of acidic deposition on natural ecosystems. Analyses reported herein quantify relations among chemical indicators and metrics of fish community health and biodiversity in streams of the Adirondack Park. This information is used to indicate levels of atmospheric deposition necessary to alleviate harmful effects on fish populations. Results of this investigation provide a framework that can be applied to better understand how modeled stream acid neutralizing capacity (ANC) values that are developed to support TL investigations can be adjusted to reflect high-flow ANC values that may be associated with toxic conditions. Since process models are often calibrated to a low-flow or average flow condition, the magnitude and spatial extent of TL exceedances increase substantially when episodic acidification is considered.

New York↗

USGS2026

Environmental tradeoffs of urban stream restoration in Fairfax County, Virginia

Regulatory mandates to improve water quality and stream health have driven substantial investment in stream restoration. Most projects aim to improve channel-floodplain connectivity, reduce sediment erosion, and enhance habitat for aquatic organisms, yet few include adequate pre- and post-restoration monitoring to assess outcomes. Since 2007, Fairfax County, Virginia, and the U.S. Geological Survey have partnered to monitor and evaluate water-quality conditions in Flatlick Branch. In 2018, a 1.72-km reach of stream above the monitoring station was restored using a Natural Channel Design approach. This study applied the Stream Functions Pyramid (SFP) framework to evaluate restoration tradeoffs. Post-restoration, watershed hydrology remained largely unchanged, but channel modifications increased flow capacity, reduced velocity, and further disconnected the channel from the floodplain. Nutrient and sediment reductions exceeded expected amounts, but the removal of over 20 % of riparian tree canopy increased physicochemical variability and the frequency and magnitude of water temperature heatwaves. Post-restoration, state standards for low dissolved oxygen and elevated pH were exceeded 2.5 and 7.5 times more often, respectively. Gross primary production and ecosystem respiration increased and organic matter sources supporting metabolism shifted from allochthonous to autochthonous. Trends in several benthic macroinvertebrate metrics, which were improving prior to construction, have since plateaued or declined, and the fish assemblage shifted from a native minnow dominated community to non-native, warmwater tolerant taxa. This study highlights the need for comprehensive assessments of stream restoration and benefits of using the SFP to understand the consequences and possible tradeoffs of different ecosystem management decisions.

Virginia↗

USGS2011

Anthropogenic disturbance and landscape patterns affect diversity patterns of aquatic benthic macroinvertebrates

Measures of species diversity are valuable tools for assessing ecosystem health. However, most assessments have addressed individual sites or regional taxon pools, with few comparisons of differences in assemblage composition within or among regions. We examined the effects of anthropogenic disturbance on local richness (α diversity) and species turnover (β diversity) of benthic macroinvertebrates in small streams within and between 2 ecoregions (Northern Piedmont vs Southeastern Plains ecoregions) of the Patuxent River basin (Maryland, USA). Regional species pools did not differ between ecoregions (Piedmont = 166 taxa, Plains = 162 taxa); however, local richness was lower in the Plains (mean = 17.4 taxa/stream) compared to the Piedmont (mean = 22.2 taxa/stream). When streams were categorized into disturbance classes (low, medium, high), local richness did not differ among categories for either region. However, at the entire Patuxent scale, local richness tended to decrease with % impervious cover in a watershed. Variation in species composition, analyzed with nonmetric multidimensional scaling (nMDS), differed significantly between Piedmont and Plains streams, and Plains streams had higher β diversity than Piedmont streams. When partitioned by disturbance category and region, β diversity differed only between the low-disturbance sites (Plains > Piedmont). Relationships between β diversity and environmental variables varied by region. β diversity was weakly negatively related to % row-crop cover in a watershed at the entire Patuxent scale. For the Piedmont region, β diversity tended to decrease with % forest, % pasture, and % row-crop cover in a watershed. Such negative relationships between β diversity and landuse variables indicate a possible homogenization of the assemblage. The incongruence between diversity measures and composition measures, together with differing effects of anthropogenic land use on β diversity in the 2 regions, emphasizes the need to incorporate both α and β diversity and regional environmental factors in conservation/land management studies.

Maryland↗

USGS2020

Cytology reveals diverse cell morphotypes and cellin-cell interactions in normal collector sea urchins Tripneustes gratilla

Echinoderms such as sea urchins are important in marine ecosystems, particularly as grazers, and unhealthy sea urchins can have important ecological implications. For instance, unexplained mortalities of Diadema antillarum in the Caribbean were followed by algal overgrowth and subsequent collapse of coral reef ecosystems. Unfortunately, few tools exist to evaluate echinoderm health, making management of mortalities or other health issues problematic. Hematology is often used to assess health in many animal groups, including invertebrates, but is seldom applied to echinoderms. We used a standard gravitometric technique to concentrate fixed coelomocytes from the collector sea urchin Tripneustes gratilla onto microscope slides, permitting staining and enumeration. Using Romanowsky stain and electron microscopy to visualize cell details, we found that urchin cells could be partitioned into different morphotypes. Specifically, we enumerated phagocytes, phagocytes with perinuclear cytoplasmic dots, vibratile cells, colorless spherule cells, red spherule cells, and red spherule cells with pink granules. We also saw cell-in-cell interactions characterized by phagocytes apparently phagocytizing mainly the motile cells including red spherule cells, colorless spherule cells, and vibratile cells disproportionate to underlying populations of circulating cells. Cell-in-cell interactions were seen in 71% of sea urchins, but comprised <1% of circulating cells. Finally, about 40% of sea urchins had circulating phagocytes that were apparently phagocytizing spicules. The coelomic fluid collection and slide preparation methods described here are simple, field portable, and might be a useful complementary tool for assessing health of other marine invertebrates, revealing heretofore unknown physiological phenomena in this animal group.

Hawaii↗

USGS2010

Global change and water resources in the next 100 years

We are in the midst of a continental-scale, multi-year experiment in the United States, in which we have not defined our testable hypotheses or set the duration and scope of the experiment, which poses major water-resources challenges for the 21st century. What are we doing? We are expanding population at three times the national growth rate in our most water-scarce region, the southwestern United States, where water stress is already great and modeling predicts decreased streamflow by the middle of this century. We are expanding irrigated agriculture from the west into the east, particularly to the southeastern states, where increased competition for ground and surface water has urban, agricultural, and environmental interests at odds, and increasingly, in court. We are expanding our consumption of pharmaceutical and personal care products to historic high levels and disposing them in surface and groundwater, through sewage treatment plants and individual septic systems. These substances are now detectable at very low concentrations and we have documented significant effects on aquatic species, particularly on fish reproduction function. We don’t yet know what effects on human health may emerge, nor do we know if we need to make large investments in water treatment systems, which were not designed to remove these substances. These are a few examples of our national-scale experiment. In addition to these water resources challenges, over which we have some control, climate change models indicate that precipitation and streamflow patterns will change in coming decades, with western mid-latitude North America generally drier. We have already documented trends in more rain and less snow in western mountains. This has large implications for water supply and storage, and groundwater recharge. We have documented earlier snowmelt peak spring runoff in northeastern and northwestern States, and western montane regions. Peak runoff is now about two weeks earlier than it was in the first half of the 20th century. Decreased summer runoff affects water supply for agriculture, domestic water supply, cooling needs for thermoelectric power generation, and ecosystem needs. In addition to the reduced volume of streamflow during warm summer months, less water results in elevated stream temperature, which also has significant effects on cooling of power generating facilities and on aquatic ecosystem needs. We are now required to include fish and other aquatic species in negotiation over how much water to leave in the river, rather than, as in the past, how much water we could remove from a river. Additionally, we must pay attention to the quality of that water, including its temperature. This is driven in the US by the Endangered Species Act and the Clean Water Act. Furthermore, we must now better understand and manage the whole hydrograph and the influence of hydrologic variability on aquatic ecosystems. Man has trimmed the tails off the probability distribution of flows. We need to understand how to put the tails back on but can’t do that without improved understanding of aquatic ecosystems. Sea level rise presents challenges for fresh water extraction from coastal aquifers as they are compromised by increased saline intrusion. A related problem faces users of ‘run-of-the-river’ water-supply intakes that are threatened by a salt front that migrates further upstream because of higher sea level. We face significant challenges with water infrastructure. The U.S. has among the highest quality drinking water in the world piped to our homes. However, our water and sewage treatment plants and water and sewer pipelines have not had adequate maintenance or investment for decades. The US Environmental Protection Agency estimates that there are up to 3.5M illnesses per year from recreational contact with sewage from sanitary sewage overflows. Infrastructure investment needs have been put at 5 trillion nationally. Global change and water resources c

Conference Paper↗

USGS2014

An ecological response model for the Cache la Poudre River through Fort Collins

The Poudre River Ecological Response Model (ERM) is a collaborative effort initiated by the City of Fort Collins and a team of nine river scientists to provide the City with a tool to improve its understanding of the past, present, and likely future conditions of the Cache la Poudre River ecosystem. The overall ecosystem condition is described through the measurement of key ecological indicators such as shape and character of the stream channel and banks, streamside plant communities and floodplain wetlands, aquatic vegetation and insects, and fishes, both coolwater trout and warmwater native species. The 13- mile-long study area of the Poudre River flows through Fort Collins, Colorado, and is located in an ecological transition zone between the upstream, cold-water, steep-gradient system in the Front Range of the Southern Rocky Mountains and the downstream, warm-water, low-gradient reach in the Colorado high plains. The City wanted to better understand the ecological response of the Poudre River ecosystem to potential changes in stream flow and other physical parameters through the conceptual framework of a multivariable integrated model. This goal was met through the use of a probabilistic model based on Bayesian concepts. This construct allowed the integration of a wide range of data and expert opinion (as informed by local data) to predict potential changes to ecosystem conditions under various flow scenarios. Nine flow scenarios representing past, present, and possible future hydrology were developed as the primary model input. Both reach-scale drivers such as stream channel conditions and pollutant loads, as well as ecological conditions, including species composition, interactions, and habitat requirements influenced model-predicted ecosystem outcomes. Model output consisted of probability distributions for eight ecological indicators collectively representing the physical setting, aquatic life, and riparian habitats of the river ecosystem. We are confident in model predictions related to probable trends, relative magnitude of changes and potential ecosystem responses to changing flow conditions, though data availability and the process of converting diverse data types into a common unit (probabilities) limit precision of individual results. Key findings suggest that: The present ecological function of the Poudre River is altered as a result of more than 150 years of human influences that include highly managed flows, urbanization, gravel mining, channelization and urban and industrial encroachment in the floodplain, underscoring the vulnerable and complex character of the Poudre River; A continuation of today’s flow management will lead to ongoing changes in ecosystem condition, and additional water depletions will compromise ecological conditions; High flows play an essential role in maintaining and improving the aquatic and riparian condition of the river; Adequate flows in base-flow periods are critical to desirable water quality, and thriving fish and insect populations; Improvement of native aquatic life is possible if issues related to channel modifications, siltation, invasive species, and base and high flow conditions are managed properly; The present confined river channel and modified flows has reduced the potential for a keystone and iconic species, plains cottonwood, to be self-sustaining in the study area; The streamside corridor retains the potential to support a functioning riparian forest that provides important ecological services if periodic floodplain inundation occurs. Environmental flows that combine stable and adequate flows in base-flow periods with occasional rejuvenating high flows that meet target levels defined in this study are likely improve all biological indicators across the system. ERM test scenarios that include both stable base flows and rejuvenating high flows indicate that substantial improvements in the river ecosystem can be achieved with improved management of flow volumes similar to those observed in the river during the last half century of intensive water development. These results underscore the possibility of improving the river ecosystem through active management while still maintaining the Poudre’s diverse economic benefits and role as a working river. The ERM was designed to represent the multi-dimensional ecological character of the contemporary urban Poudre River. It provides a scientific foundation that can serve as a decision support tool and foster a more informed community discussion about the future of the river as it provides a better understanding of the likely response of the Poudre River ecosystem to environmental flow management and other stewardship activities. In particular, model results can assist managers in developing specific management actions to achieve desirable goals for key indicators of river health.

Colorado↗

USGS2021

Synthesis of data and studies relating to Delta Smelt biology in the San Francisco Estuary, emphasizing water year 2017

In the San Francisco Estuary (SFE), the effects of freshwater flow on the aquatic ecosystem have been studied extensively over the years and remains a contentious management issue. It is especially contentious with regards to the Delta Smelt (Hypomesus transpacificus), a species endemic to the SFE that has been listed as threatened under the Federal Endangered Species Act and endangered by the State of California. Early studies of Delta Smelt distribution within the SFE suggested that Delta Smelt habitat is determined largely by freshwater flow; however, the exact mechanisms and processes producing such benefits remained unclear. In the summer of 2017, the Flow Alteration Management, Analysis, and Synthesis Team (FLOAT-MAST) was established to analyze, synthesize, and summarize the data collected from the various flow-related monitoring and special studies occurring in 2017(see Table Intro 4). This report will focus on the 2017 summer-fall status of Delta Smelt and its habitat following a record wet year. There has been a long-term decline in the abundance of Delta Smelt associated with a decline in other pelagic fishes. Investigators concluded that the decline has likely been caused by the interactive effects of several causes, including changes in both physical and biotic habitats, many of which are tied to amount and timing of freshwater flow. For this report, we formulated a number of basic predictions about the likely effects of high flows in 2017 on Delta Smelt and their habitat (Table 3). We use a qualitative weight of evidence approach to evaluate whether these predictions were supported by available data. Data sources included a variety of long-term monitoring surveys conducted by Interagency Ecological Program (IEP) agencies, as well as model outputs. Delta Smelt population, health, and life history metrics rarely responded as predicted. Water temperature appears to have a stronger effect on Delta Smelt growth rate and some metrics of life history diversity than outflow or X2 position. Other life history diversity attributes varied but did not appear to be driven by outflow or temperature. Health status was difficult to interpret. Low prevalence of lesions and improved nutritional condition during the drought was contradicted by declining overall population levels. Because of the sparse catches of Delta Smelt in the post-POD years, we consider the data insufficient to reach firm conclusions about the predictions concerning range and distribution of Delta Smelt, especially in the fall. The prediction of high survival was not supported. The 2017 Delta Smelt year class began with poor recruitment in spring of 2017 and below average survival for spring to summer and summer to fall. Thus, low production and low survival led to low abundance of all life stages. During the fall to winter period survival improved, yet the resulting adults were low in number. Foraging success of the fish captured, as measured by stomach fullness, was high for juveniles and adults in 2017 relative to recent years associated with the higher densities of common zooplankton prey that occurred in 2017.

California↗