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USGS2026

Perspectives and insights gained from applying landscape ecological approaches to the Upper Mississippi riverscape

Advances in remote sensing, spatial data collection, hydraulic and geospatial models, and the maturation of landscape ecology during the early 2000s spurred the concept of rivers as landscapes or ‘riverscapes’. Since that time, the Upper Mississippi River Restoration (UMRR) Program - one of the world’s longest running large-river ecosystem restoration and monitoring programs - has applied landscape ecological principles to the Upper Mississippi River System (UMRS). I examine spatial patterns of aquatic nutrient concentrations, submersed aquatic vegetation, and fish and mussel communities, finding that within-river patterns are often patchy in nature, likely resulting from how nutrient processes and community traits interact with spatial variability in hydraulic exchange patterns. Local-scale patchy spatial patterns in the UMRS are embedded in system-scale longitudinal gradients and a hierarchical view of the river has provided a foundation for strategic river restoration planning. Key Words: Aquatic Habitat, hydraulic connectivity, patch, restoration, riverscape

BioScience↗

USGS2022

Influences of channel and floodplain modification on expansion of woody vegetation into Catahoula Lake, Louisiana, USA

Ecosystem structure of wetlands in managed floodplains depends on hydrological processes controlled by geomorphology and water management. Overlapping effects of direct modifications and geomorphic adjustments to management can combine to trigger changes to floodplain ecosystem structure. We examined the case of woody vegetation encroaching into the depressional Catahoula Lake, Louisiana, in the context of regional hydrologic and geomorphic modification in the floodplain of the Mississippi River. Historical aerial photographs indicated woody encroachment into Catahoula Lake for at least 80 years, and the rate of expansion has increased in recent decades. Historical stage analysis revealed that the downstream Red–Atchafalaya–Mississippi River system controls the lower limit of the lake water level when the large rivers are high, but channel enlargement and other hydrological changes there have reduced the frequency of backwater flooding by 42% since 1880. In addition, operation of the water control structure on the lake has altered its hydrological regime to be more regular among years. Historic stage analysis revealed current lake levels are lower in the high-water spring, less variable in the dry period, and lack the extreme high-water events of 100+ years ago, all of which facilitate the expansion of woody vegetation.

Louisiana↗

USGS2006

Modeling the influence of river rehabilitation scenarios on bed material sediment flux in a large river over decadal timescales

A stochastic flood generator and calibrated sediment transport formulae were used to assess the decadal impact of major river rehabilitation strategies on two fraction bed material sediment flux and net storage, first‐order indicators of aquatic riverine habitat, in a large river system. Model boundary conditions were modified to reflect the implementation of three major river rehabilitation strategies being considered in the Sacramento River Valley: gravel augmentation, setting back of levees, and flow alteration. Fifty 30‐year model simulations were used to compute probabilities of the response in sediment flux and net storage to these strategies. Total annual average bed material sediment flux estimates were made at six gauged river cross sections, and ∼60 km reach‐scale sediment budgets were evaluated between them. Gravel augmentation to improve spawning habitat induced gravel accumulation locally and/or downstream, depending on the added mixture. Levee setbacks to recreate the river corridor reduced flow stages for most flows and hence lowered sediment flux. Flow alteration to mimic natural flow regimes systematically decreased total annual average flux, suggesting that high‐magnitude low‐frequency transport events do not affect long‐term trends in bed material flux. The results indicate that each rehabilitation strategy reduces sediment transport in its target reaches and modulates imbalances in total annual bed material sediment budgets at the reach scale. Additional risk analysis is necessary to identify extreme conditions associated with variable hydrology that could affect rehabilitation over decades. Sensitivity analysis suggests that sorting of bed material sediment is the most important determinant of modeled transport and storage patterns.

Water Resources Research↗

USGS2015

Brown Trout removal effects on short-term survival and movement of Myxobolus cerebralis-resistant rainbow trout

Following establishment of Myxobolus cerebralis (the parasite responsible for salmonid whirling disease) in Colorado, populations of Rainbow Trout Oncorhynchus mykiss experienced significant declines, whereas Brown Trout Salmo trutta densities increased in many locations across the state, potentially influencing the success of M. cerebralis -resistant Rainbow Trout reintroductions. We examined the effects of Brown Trout removal on the short-term (3-month) survival and movement of two crosses of reintroduced, M. cerebralis -resistant Rainbow Trout in the Cache la Poudre River, Colorado. Radio frequency identification passive integrated transponder tags and antennas were used to track movements of wild Brown Trout and stocked Rainbow Trout in reaches where Brown Trout had or had not been removed. Multistate mark–recapture models were used to estimate tagged fish apparent survival and movement in these sections 3 months following Brown Trout removal. A cross between the German Rainbow Trout and Colorado River Rainbow Trout strains exhibited similar survival and movement probabilities in the reaches, suggesting that the presence of Brown Trout did not affect its survival or movement. However, a cross between the German Rainbow Trout and Harrison Lake Rainbow Trout exhibited less movement from the reach in which Brown Trout had been removed. Despite this, the overall short-term benefits of the removal were equivocal, suggesting that Brown Trout removal may not be beneficial for the reintroduction of Rainbow Trout. Additionally, the logistical constraints of conducting removals in large river systems are substantial and may not be a viable management option in many rivers.

Colorado↗

USGS2004

Evaluation of ground-water contribution to streamflow in coastal Georgia and adjacent parts of Florida and South Carolina

Stream-aquifer relations in the coastal area of Georgia and adjacent parts of Florida and South Carolina were evaluated as part of the Coastal Georgia Sound Science Initiative, the Georgia Environmental Protection Division's strategy to protect the Upper Floridan aquifer from saltwater intrusion. Ground-water discharge to streams was estimated using three methods: hydrograph separation, drought-streamflow measurements, and linear-regression analysis of streamflow duration. Ground-water discharge during the drought years of 1954, 1981, and 2000 was analyzed for minimum ground-water contribution to streamflow. Hydrograph separation was used to estimate baseflow at eight streamflow gaging stations during the 31-year period 1971?2001. Six additional streamflow gaging stations were evaluated using linear-regression analysis of flow duration to determine mean annual baseflow. The study area centers on three major river systems ? the Salkehatchie?Savannah?Ogeechee, Altamaha?Satilla?St Marys, and Suwannee ? that interact with the underlying ground-water system to varying degrees, largely based on the degree of incision of the river into the aquifer and on the topography. Results presented in this report are being used to calibrate a regional ground-water flow model to evaluate ground-water flow and stream-aquifer relations of the Upper Floridan aquifer. Hydrograph separation indicated decreased baseflow to streams during drought periods as water levels declined in the aquifer. Average mean annual baseflow ranged from 39 to 74 percent of mean annual streamflow, with a mean contribution of 58 percent for the period 1971?2001. In a wet year (1997), baseflow composed from 33 to 70 percent of mean annual streamflow. Drought-streamflow analysis estimated baseflow contribution to streamflow ranged from 0 to 24 percent of mean annual streamflow. Linear-regression analysis of streamflow duration estimated the Q35 (flow that is equaled or exceeded 35 percent of the time) as the most reasonable estimate of baseflow. The Q35, when compared to mean annual streamflow, estimated a baseflow contribution ranging from 65 to 102 percent of streamflow. The Q35 estimate tends to overestimate baseflow as evidenced by the baseflow contribution greater than 100 percent. Ground-water contributions to streamflow are greatest during winter when evapotranspiration is low, and least during summer when evapotranspiration is high. Baseflow accounted for a larger percentage of streamflow at gaging stations in the Salkehatchie?Savannah?Ogeechee River Basin than in the other two basins. This difference is due largely to the availability of data, proximity to the Piedmont physiographic province where the major rivers originate and are by supplied ground water, and proximity to the upper Coastal Plain where there is greater topographic relief and interconnection between streams and aquifers.

Florida, Georgia, South Carolina↗

USGS2014

Anthropogenic disturbance and environmental associations with fish assemblage structure in two nonwadeable rivers

Nonwadeable rivers are unique ecosystems that support high levels of aquatic biodiversity, yet they have been greatly altered by human activities. Although riverine fish assemblages have been studied in the past, we still have an incomplete understanding of how fish assemblages respond to both natural and anthropogenic influences in large rivers. The purpose of this study was to evaluate associations between fish assemblage structure and reach-scale habitat, dam, and watershed land use characteristics. In the summers of 2011 and 2012, comprehensive fish and environmental data were collected from 33 reaches in the Iowa and Cedar rivers of eastern-central Iowa. Canonical correspondence analysis (CCA) was used to evaluate environmental relationships with species relative abundance, functional trait abundance (e.g. catch rate of tolerant species), and functional trait composition (e.g. percentage of tolerant species). On the basis of partial CCAs, reach-scale habitat, dam characteristics, and watershed land use features explained 25.0–81.1%, 6.2–25.1%, and 5.8–47.2% of fish assemblage variation, respectively. Although reach-scale, dam, and land use factors contributed to overall assemblage structure, the majority of fish assemblage variation was constrained by reach-scale habitat factors. Specifically, mean annual discharge was consistently selected in nine of the 11 CCA models and accounted for the majority of explained fish assemblage variance by reach-scale habitat. This study provides important insight on the influence of anthropogenic disturbances across multiple spatial scales on fish assemblages in large river systems.

Iowa↗

USGS2005

Middle Mississippi River decision support system: user's manual

This user's manual describes the Middle Mississippi River Decision Support System (MMRDSS) and gives detailed examples on its use. The MMRDSS provides a framework to assist decision makers regarding natural resource issues in the Middle Mississippi River floodplain. The MMRDSS is designed to provide users with a spatially explicit tool for tasks, such as inventorying existing knowledge, developing models to investigate the potential effects of management decisions, generating hypotheses to advance scientific understanding, and developing scientifically defensible studies and monitoring. The MMRDSS also includes advanced tools to assist users in evaluating differences in complexity, connectivity, and structure of aquatic habitats among river reaches. The Environmental Systems Research Institute ArcView 3.x platform was used to create and package the data and tools of the MMRDSS.

Techniques and Methods↗

USGS1995

Biota of the upper Mississippi River ecosystem

The Mississippi River is one of the world's major river systems in size, habitat and biotic diversity, and biotic productivity. The navigable Upper Mississippi River, extending 1,370 km (850 mi) from St. Anthony Falls (Minnesota) to the confluence with the Ohio River, has been impounded by 27 locks and dams to enhance commercial navigation. The reach between two consecutive locks and dams is termed a "pool." The upstream portions of many pools are similar to the unimpounded river, whereas the downstream reaches are similar to reservoirs.

Upper Mississippi River↗

USGS2005

Historical backcasting of metal concentrations in the Chattahoochee River, Georgia: Population growth and environmental policy

The impact of increasing urbanization on the quality of a river system has been investigated by examining the current concentration of trace metals in the Chattahoochee River south of Atlanta, GA, and comparing these to previously published historical sediment data from reservoirs along the river. The lack of historical data for dissolved metal concentrations prior to ???1980 requires an approach using these historic metal data from sediment cores. Core data are combined with current suspended load and dissolved metal data to "backcast" dissolved metal concentrations in the metro-Atlanta portion of the Chattahoochee River. The data suggest that the per capita input of dissolved trace metals have actually decreased since the 1920s, but anthropogenic inputs of metal are still a substantial water quality issue. ?? 2005 Elsevier Ltd. All rights reserved.

Applied Geochemistry↗

USGS2024

PFAS river export analysis highlights the urgent need for catchment-scale mass loading data

Source apportionment of per- and polyfluoroalkyl substances (PFAS) requires an understanding of the mass loading of these compounds in river basins. However, there is a lack of temporally variable and catchment-scale mass loading data, meaning identification and prioritization of sources of PFAS to rivers for management interventions can be difficult. Here, we analyze PFAS concentrations and loads in the River Mersey to provide the first temporally robust estimates of PFAS export for a European river system and the first estimates of the contribution of wastewater treatment works (WwTWs) to total river PFAS export. We estimate an annual PFAS export of 68.1 kg for the River Mersey and report that the yield of perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) in the catchment is among the highest recorded globally. Analysis of river and WwTW loads indicates approximately one-third of PFOA emitted from WwTWs is potentially stored in the catchment and approximately half of PFOS transported by the River Mersey may not originate from WwTWs. As governments move toward regulation of PFAS in WwTW effluents, our findings highlight the complexity of PFAS source apportionment and the need for catchment-scale mass loading data. This study indicates that strategies for reducing PFAS loading that focus solely on WwTW effluents may not achieve river water quality targets.

Environmental Science & Technology Letters↗

USGS2011

Seasonal Distribution and Movements of Atlantic and Shortnose Sturgeon in the Penobscot River Estuary, Maine

Relatively little is known about the distribution and seasonal movement patterns of shortnose sturgeon Acipenser brevirostrum and Atlantic sturgeon Acipenser oxyrinchus oxyrinchus occupying rivers in the northern part of their range. During 2006 and 2007, 40 shortnose sturgeon (66–113.4 cm fork length [FL]) and 8 Atlantic sturgeon (76.2–166.2 cm FL) were captured in the Penobscot River, Maine, implanted with acoustic transmitters, and monitored using an array of acoustic receivers in the Penobscot River estuary and Penobscot Bay. Shortnose sturgeon were present year round in the estuary and overwintered from fall (mid-October) to spring (mid-April) in the upper estuary. In early spring, all individuals moved downstream to the middle estuary. Over the course of the summer, many individuals moved upstream to approximately 2 km of the downstream-most dam (46 river kilometers [rkm] from the Penobscot River mouth [rkm 0]) by August. Most aggregated into an overwintering site (rkm 36.5) in mid- to late fall. As many as 50% of the tagged shortnose sturgeon moved into and out of the Penobscot River system during 2007, and 83% were subsequently detected by an acoustic array in the Kennebec River, located 150 km from the Penobscot River estuary. Atlantic sturgeon moved into the estuary from the ocean in the summer and concentrated into a 1.5-km reach. All Atlantic sturgeon moved to the ocean by fall, and two of these were detected in the Kennebec River. Although these behaviors are common for Atlantic sturgeon, regular coastal migrations of shortnose sturgeon have not been documented previously in this region. These results have important implications for future dam removals as well as for rangewide and river-specific shortnose sturgeon management.

Maine↗

USGS2005

Concentrations of organic contaminants detected during managed flow conditions, San Joaquin River and Old River, California, 2001

Concentrations of organic contaminants were determined in water samples collected at six surface-water sites located along the San Joaquin and Old Rivers during April through June 2001. Water samples were collected, coincident with salmon smolt caging studies conducted by researchers from the Bodega Marine Laboratory at the University of California at Davis to characterize exposure of the salmon smolt to organic contaminants. Sampling occurred prior to, during, and following the implementation of managed streamflow conditions on the San Joaquin and Old Rivers as part of the Vernalis Adaptive Management Plan. Thirteen pesticides were detected in water samples collected during this study, and at least five pesticides were detected in each sample. The total number of pesticide detections varied little between river systems and between sites, but the maximum concentrations of most pesticides occurred in San Joaquin River samples. The total number of pesticides detected varied little over the three time periods. However, during the period of managed streamflow, the fewest number of pesticides were detected at their absolute maximum concentration. Nine wastewater compounds were detected during this study. Suspended-sediment concentrations were similar for the San Joaquin and Old Rivers except during the period of managed streamflow conditions, when suspended-sediment concentration was higher at sites on the San Joaquin River than at sites on the Old River. Values for water parameters (pH, specific conductance, and hardness) were lowest during the period of managed flows.

Data Series↗

USGS1999

Summary of information on synthetic organic compounds and trace elements in tissue of aquatic biota, Clark Fork-Pend Oreille and Spokane River basins, Montana, Idaho, and Washington, 1974-96

As part of the Northern Rockies Intermontane Basins study of the National Water-Quality Assessment Program, data collected between 1974 and 1996 were compiled to describe contaminants in tissue of riverine species. Tissue-contaminant data from 11 monitoring programs and studies representing 28 sites in the study area were summarized. Tissue-contaminant data for most streams generally were lacking. Many studies have focused on and around mining-affected areas on the Clark Fork and Coeur d'Alene Rivers and their major tributaries. DDT and PCBs and their metabolites and congeners were the synthetic organic contaminants most commonly detected in fish tissue. Fish collected from the Spokane River in Washington contained elevated concentrations of PCB arochlors, some of which exceeded guidelines for the protection of human health and predatory wildlife. Tissue samples of fish from the Flathead River watershed contained higher-than-expected concentrations of PCBs, which might have resulted from atmospheric transport. Trace element concentrations in fish and macroinvertebrates collected in and around mining areas were elevated compared with background concentrations. Some cadmium, copper, lead, and mercury concentrations in fish tissue were elevated compared with results from other studies, and some exceeded guidelines. Macroinvertebrates from the Coeur d'Alene River contained higher concentrations of cadmium, lead, and zinc than did macroinvertebrates from other river systems in mining-affected areas. A few sportfish fillet samples, most from the Spokane River in Washington, were collected to assess human health risk. Concentrations of PCBs in these fillets exceeded screening values for the protection of human health. At present, there is no coordinated, long-term fish tissue monitoring program for rivers in the study area, even though contaminants are present in fish at levels considered a threat to human health. Development of a coordinated, centralized national data base for contaminants in fish tissue is needed. The National Water-Quality Assessment Program can provide a framework for other agencies to evaluate tissue contaminants in the Northern Rockies Intermontane Basins study area. As of 1996, there are no fish consumption advisories or fishing restrictions as a result of elevated contaminants on any rivers within the study area.

Idaho, Montana, Washington↗

USGS2014

Scaling up watershed model parameters--Flow and load simulations of the Edisto River Basin

The Edisto River is the longest and largest river system completely contained in South Carolina and is one of the longest free flowing blackwater rivers in the United States. The Edisto River basin also has fish-tissue mercury concentrations that are some of the highest recorded in the United States. As part of an effort by the U.S. Geological Survey to expand the understanding of relations among hydrologic, geochemical, and ecological processes that affect fish-tissue mercury concentrations within the Edisto River basin, analyses and simulations of the hydrology of the Edisto River basin were made with the topography-based hydrological model (TOPMODEL). The potential for scaling up a previous application of TOPMODEL for the McTier Creek watershed, which is a small headwater catchment to the Edisto River basin, was assessed. Scaling up was done in a step-wise process beginning with applying the calibration parameters, meteorological data, and topographic wetness index data from the McTier Creek TOPMODEL to the Edisto River TOPMODEL. Additional changes were made with subsequent simulations culminating in the best simulation, which included meteorological and topographic wetness index data from the Edisto River basin and updated calibration parameters for some of the TOPMODEL calibration parameters. Comparison of goodness-of-fit statistics between measured and simulated daily mean streamflow for the two models showed that with calibration, the Edisto River TOPMODEL produced slightly better results than the McTier Creek model, despite the significant difference in the drainage-area size at the outlet locations for the two models (30.7 and 2,725 square miles, respectively). Along with the TOPMODEL hydrologic simulations, a visualization tool (the Edisto River Data Viewer) was developed to help assess trends and influencing variables in the stream ecosystem. Incorporated into the visualization tool were the water-quality load models TOPLOAD, TOPLOAD-H, and LOADEST. Because the focus of this investigation was on scaling up the models from McTier Creek, water-quality concentrations that were previously collected in the McTier Creek basin were used in the water-quality load models.

South Carolina↗

USGS2013

Woody vegetation communities of tidal freshwater swamps in South Carolina, Georgia and Florida (US) with comparisons to similar systems in the US and South America

Questions What are the general tree communities found in tidal freshwater swamps along four large coastal rivers in the southeastern United States (US)? How do these communities compare to other tidal freshwater swamps in the US and South America? Locations Tidal floodplains of major rivers along the Atlantic and Gulf coasts of the southeastern US: Savannah, Altamaha, Suwannee and Apalachicola Rivers. Methods An extensive survey of trees and shrubs was conducted to describe the communities from a range of tidal freshwater swamps. River basins studied include micro-tidal (Gulf coast) and meso-tidal (Atlantic coast) regimes, and study areas were located both near and distant to primary channels. A total of 128 plots (100 m2 each) were inventoried, distributed evenly over the Savannah and Altamaha Rivers along the Atlantic coast, and the Suwannee and Apalachicola Rivers along the Gulf coast. Multivariate statistics helped discern communities and the significant indicator species in each. Results Four general communities were characterized and named according to the strongest individual indicator species in each: Water Tupelo (Nyssa aquatica) Community, Swamp Tupelo (Nyssa biflora) Community, Dwarf Palmetto (Sabal minor) Community and Cabbage Palm (Sabal palmetto) Community. Conclusions Descriptions of most tidal freshwater swamps in the southeastern US fit within the communities described in this study. Because studies that make inferences between environmental drivers (e.g. salinity, hydroperiod, hurricanes) and specific community types are best applied to the same communities (but perhaps different river systems), this work provides a framework by which tidal freshwater forested wetlands can be accurately compared based on their tree communities. We suggest that, within the broad range of our inventories, the four communities described identify the primary associations that should be tracked within most tidal freshwater swamps of the US. However, we identify some river basins in the US that do not fit this construct. Diversity of major tree communities in tidal freshwater swamps outside the US is generally much lower (with the notable exception of Amazonian hardwood tidal várzea), as are basal area values.

Georgia;Florida;South Carolina↗

USGS2024

Increasing seasonal variation in the extent of rivers and lakes from 1984 to 2022

Knowledge of the spatial and temporal distribution of surface water is important for water resource management, flood risk assessment, monitoring ecosystem health, constraining estimates of biogeochemical cycles and understanding our climate. While global-scale spatiotemporal change detection of surface water has significantly improved in recent years due to planetary-scale remote sensing and computing, it has remained challenging to distinguish the changing characteristics of rivers and lakes. Here we analyze the spatial extent of permanent and seasonal rivers and lakes globally over the past 38 years based on new data of river system extents and surface water trends. Results show that while the total permanent surface area of both rivers and lakes has remained relatively constant, the areas with intermittent seasonal coverage have increased by 12 % and 27 % for rivers and lakes, respectively. The increase is statistically significant in over 84 % of global water catchments based on Spearman's rank correlations (rho) above 0.05 and p values less than 0.05. The seasonal river extent is nearly 32 % larger than the previously observed annual mean river extent, suggesting large seasonal variations that impact not only ecosystem health but also estimations of terrestrial biogeochemical cycles of carbon. The outcomes of our analysis are shared as the Surface Area of Rivers and Lakes (SARL) database, serving as a valuable resource for monitoring and research of hydrological cycles, ecosystem accounting, and water management.

Hydrology and Earth System Sciences↗

USGS2006

Preface: Bridging the gap between theory and practice on the upper Mississippi River

In July 1994, the Upper Mississippi River (UMR) served as a nexus for coalescing scientific information and management issues related to worldwide floodplain river ecosystems. The objective of the conference ‘Sustaining the Ecological Integrity of Large Floodplain Rivers: Application of Ecological Knowledge to River Management’, was to provide presentations of current ideas from the scientific community. To translate the many lessons learned on other river systems to operational decisions on the UMR, a companion workshop for managers and the general public was held immediately after the conference. An immediate local need for such sharing has existed for several years, as the U.S. Corps of Engineers is currently planning commercial navigation activities that will influence the ecological integrity of the river over the next half century. Recently, other equally important management issues have surfaced, including managing the river as an element of the watershed, and assessing its ecological value as a system instead of a collection of parts (Upper Mississippi River Conservation Committee, 1993). Regional and state natural resource agencies are becoming more convinced that they need to address these issues within their own authorities, however spatially limited, rather than relying on the U.S. Corps of Engineers to manage the ecosystem as an adjunct to its purpose of navigation support.

Mississippi River↗

USGS2013

Sedimentology of new fluvial deposits on the Elwha River, Washington, USA, formed during large-scale dam removal

Removal of two dams 32 m and 64 m high on the Elwha River, Washington, USA, provided the first opportunity to examine river response to a dam removal and controlled sediment influx on such a large scale. Although many recent river-restoration efforts have included dam removal, large dam removals have been rare enough that their physical and ecological effects remain poorly understood. New sedimentary deposits that formed during this multi-stage dam removal result from a unique, artificially created imbalance between fluvial sediment supply and transport capacity. River flows during dam removal were essentially natural and included no large floods in the first two years, while draining of the two reservoirs greatly increased the sediment supply available for fluvial transport. The resulting sedimentary deposits exhibited substantial spatial heterogeneity in thickness, stratal-formation patterns, grain size and organic content. Initial mud deposition in the first year of dam removal filled pore spaces in the pre-dam-removal cobble bed, potentially causing ecological disturbance but not aggrading the bed substantially at first. During the second winter of dam removal, thicker and in some cases coarser deposits replaced the early mud deposits. By 18 months into dam removal, channel-margin and floodplain deposits were commonly >0.5 m thick and, contrary to pre-dam-removal predictions that silt and clay would bypass the river system, included average mud content around 20%. Large wood and lenses of smaller organic particles were common in the new deposits, presumably contributing additional carbon and nutrients to the ecosystem downstream of the dam sites. Understanding initial sedimentary response to the Elwha River dam removals will inform subsequent analyses of longer-term sedimentary, geomorphic and ecosystem changes in this fluvial and coastal system, and will provide important lessons for other river-restoration efforts where large dam removal is planned or proposed.

Washington↗