Effects Of Dam Removal Research Articles

Laboratory Calibration of Impact Plates for Measuring Gravel Bed Load Size and Mass

AbstractContinuous monitoring of gravel transport in rivers is necessary for understanding the effect of dam removal on river systems. Impact plates, such as those deployed on the Elwha River in th...

Recommendations for monitoring freshwater fishes in river restoration plans: A wasted opportunity for assessing impact

Abstract Many human activities in and on rivers cause the loss of freshwater biodiversity, especially fish, which now are one of the most endangered vertebrate groups. River fragmentation caused by the construction of dams is one of the main threats to fish species. In Spain, which has the highest number of dams per square kilometre in the world, more than half of all fish species are threatened by these constructions. The government has initiated the National Strategy for River Restoration, a plan to restore rivers and preserve their inhabitants, which includes the removal of dams. An information search and query was conducted to determine if fish monitoring was performed before and after dam removal, and the result was negative. Therefore, an assessment of the effects of dam removal on fish communities at a large spatial scale was not possible. Instead, an analysis was carried out to measure the effects of dam removal on river connectivity using a geometric network. The analysis of river connectivity improvement showed that 66% of removed dams had one or more dams less than 5 km away. The removal of dams increased the connected river length by an average of 6.4 km per dam removed, with the range varying between 1.04 km and 9.48 km, depending on the river basin. These results show that, although monitoring programmes are strongly recommended after restoration actions, they are not usually performed. This is a wasted opportunity to gather large datasets to understand better the effects of human actions on fish communities and on rivers. River connectivity results may reflect a demolition strategy based more on economic and social opportunism rather than on ecological considerations. It is strongly recommended that dam removal plans should be based on ecological selection methods to achieve greater river improvements with less investment.

Effects of Dam Removal on Fish Community Interactions and Stability in the Eightmile River System, Connecticut, USA.

New multivariate time-series methods have the potential to provide important insights into the effects of ecosystem restoration activities. To this end, we examined the temporal effects of dam removal on fish community interactions using multivariate autoregressive models to understand changes in fish community structure in the Eightmile River System, Connecticut, USA. We sampled fish for 6 years during the growing season; 1 year prior to, 2 years during, and for 3 years after a small dam removal event. The multivariate autoregressive analysis revealed that the site above the dam was the most reactive and least resilient sample site, followed in order by the below-dam and nearby reference site. Even 3 years after the dam removal event, the stream was still in a recovery stage that had failed to approximate the community structure of the reference site. This suggests that the reorganization of fish communities following dam removals, with the goal of ecological restoration, may take decades to centuries for the restored sites to approximate the community structure of nearby undisturbed sites. Results from this study also highlight the utility of multivariate autoregressive modeling for examining temporal interactions among species in response to adaptive management activities both in aquatic systems and elsewhere.

Status and trends of dam removal research in the United States

Aging infrastructure coupled with growing interest in river restoration has driven a dramatic increase in the practice of dam removal. With this increase, there has been a proliferation of studies that assess the physical and ecological responses of rivers to these removals. As more dams are considered for removal, scientific information from these dam‐removal studies will increasingly be called upon to inform decisions about whether, and how best, to bring down dams. This raises a critical question: what is the current state of dam‐removal science in the United States? To explore the status, trends, and characteristics of dam‐removal research in the U.S., we searched the scientific literature and extracted basic information from studies on dam removal. Our literature review illustrates that although over 1200 dams have been removed in the U.S., fewer than 10% have been scientifically evaluated, and most of these studies were short in duration (<4 years) and had limited (1–2 years) or no pre‐removal monitoring. The majority of studies focused on hydrologic and geomorphic responses to removal rather than biological and water‐quality responses, and few studies were published on linkages between physical and ecological components. Our review illustrates the need for long‐term, multidisciplinary case studies, with robust study designs, in order to anticipate the effects of dam removal and inform future decision making. WIREs Water 2017, 4:e1164. doi: 10.1002/wat2.1164This article is categorized under: Water and Life > Conservation, Management, and Awareness Engineering Water > Sustainable Engineering of Water Water and Life > Stresses and Pressures on Ecosystems

Do the Fish Return? A Qualitative Assessment of Anadromous Pacific Salmonids' Upstream Movement After Dam Removal

Abstract Basic assumptions about the ecological effects of dam removal remain untested hypotheses. In this work, I move to address this by assessing the effectiveness of dam removal as a tool to restore anadromous Pacific salmonids' (Oncorhynchus spp.) access to upstream habitat. I compiled all available post-removal data from all cases (N = 40) where anadromous salmonid restoration was a project goal in California, Oregon, and Washington from 1999 to 2011. In cases without empirical data, I contacted biologists and river managers and collected anecdotal information. I analyzed full barriers (N = 16), where upstream passage was not possible for fish, separately from partial barriers (N = 27), where fish were able to pass upstream of the dam. In three cases, dams were passable to some species but not others. In cases of full barrier removal, formerly excluded anadromous salmonids were observed to have recolonized upstream reaches in 9 of 16 cases. In cases of partial barrier removal, results were uneven; t...

Water Quality Changes Shortly After Low‐Head Dam Removal Examined With Cultural and Microbial Source Tracking Methods

AbstractShort‐term effects of low head dam removal on water quality of urbanized stream were evaluated, focusing on fecal pollution indicators. Composite river samples were analyzed for Escherichia coli concentrations, nitrates, phosphates, turbidity and human‐specific marker (HF183) and antibiotic resistance marker (tetQ) before and after dam removal during dry weather conditions. The sampled Olentangy River water in summer before the dam removal showed poor water quality with mean E. coli concentration of 439 colony forming unit (CFU)/100 mL, mean turbidity of 10 NTU and mean nutrient concentrations of 0.61 and 0.41 mg/L for nitrate and phosphate, respectively. Surprisingly, even one month after the dam removal, E. coli numbers doubled and nitrate concentration tripled compared to pre‐removal concentrations. Although the detected HF183 concentrations were below the quantifiable levels, they did not correlate with E. coli concentrations, suggesting E. coli from other than human fecal origin. The correlation between turbidity and E. coli during dry weather further suggests E. coli accumulation in impoundment sediments and release once dam was removed. These short‐term effects of dam removal on water quality should be further evaluated, especially if recreation and other beneficial uses of water in the area are expected. Copyright © 2016 John Wiley & Sons, Ltd.

Effects of Dam Removal on Tule Fall Chinook salmon Spawning Habitat in the White Salmon River, Washington

Condit Dam is one of the largest hydroelectric dams ever removed in the USA. Breached in a single explosive event in October 2011, hundreds-of-thousands of cubic metres of sediment washed down the White Salmon River onto spawning grounds of a threatened species, Columbia River tule fall Chinook salmon Oncorhynchus tshawytscha. We investigated over a 3-year period (2010–2012) how dam breaching affected channel morphology, river hydraulics, sediment composition and tule fall Chinook salmon (hereafter ‘tule salmon’) spawning habitat in the lower 1.7 km of the White Salmon River (project area). As expected, dam breaching dramatically affected channel morphology and spawning habitat due to a large load of sediment released from Northwestern Lake. Forty-two per cent of the project area that was previously covered in water was converted into islands or new shoreline, while a large pool near the mouth filled with sediments and a delta formed at the mouth. A two-dimensional hydrodynamic model revealed that pool area decreased 68.7% in the project area, while glides and riffles increased 659% and 530%, respectively. A spatially explicit habitat model found the mean probability of spawning habitat increased 46.2% after dam breaching due to an increase in glides and riffles. Shifting channels and bank instability continue to negatively affect some spawning habitat as sediments continue to wash downstream from former Northwestern Lake, but 300 m of new spawning habitat (river kilometre 0.6 to 0.9) that formed immediately post-breach has persisted into 2015. Less than 10% of tule salmon have spawned upstream of the former dam site to date, but the run sizes appear healthy and stable. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

Fish assemblage response to a small dam removal in the Eightmile River system, Connecticut, USA.

We examined the effects of the Zemko Dam removal on the Eightmile River system in Salem, Connecticut, USA. The objective of this research was to quantify spatiotemporal variation in fish community composition in response to small dam removal. We sampled fish abundance over a 6-year period (2005-2010) to quantify changes in fish assemblages prior to dam removal, during drawdown, and for three years following dam removal. Fish population dynamics were examined above the dam, below the dam, and at two reference sites by indicator species analysis, mixed models, non-metric multidimensional scaling, and analysis of similarity. We observed significant shifts in fish relative abundance over time in response to dam removal. Changes in fish species composition were variable, and they occurred within 1 year of drawdown. A complete shift from lentic to lotic fishes failed to occur within 3 years after the dam was removed. However, we did observe increases in fluvial and transition (i.e., pool head, pool tail, or run) specialist fishes both upstream and downstream from the former dam site. Our results demonstrate the importance of dam removal for restoring river connectivity for fish movement. While the long-term effects of dam removal remain uncertain, we conclude that dam removals can have positive benefits on fish assemblages by enhancing river connectivity and fluvial habitat availability.

Dam removal and anadromous salmonid (Oncorhynchus spp.) conservation in California

Dam removal is often proposed for restoration of anadromous salmonid populations, which are in serious decline in California. However, the benefits of dam removal vary due to differences in affected populations and potential for environmental impacts. Here, we develop an assessment method to examine the relationship between dam removal and salmonid conservation, focusing on dams that act as complete migration barriers. Specifically, we (1) review the effects of dams on anadromous salmonids, (2) describe factors specific to dam removal in California, (3) propose a method to evaluate dam removal effects on salmonids, (4) apply this method to evaluate 24 dams, and (5) discuss potential effects of removing four dams on the Klamath River. Our flexible rating system can rapidly assess the likely effects of dam removal, as a first step in the prioritization of multiple dam removals. We rated eight dams proposed for removal and compared them with another 16 dams, which are not candidates for removal. Twelve of the 24 dams evaluated had scores that indicated at least a moderate benefit to salmonids following removal. In particular, scores indicated that removal of the four dams on the Klamath River is warranted for salmonid conservation. Ultimately, all dams will be abandoned, removed, or rebuilt even if the timespan is hundreds of years. Thus, periodic evaluation of the environmental benefits of dam removal is needed using criteria such as those presented in this paper.

Taxonomic and ecological tradeoffs associated with small dam removals

Dams and impoundments are widely recognized as having dramatic, negative impacts on freshwater ecosystems and are frequently implicated in the plight of endangered riverine biota (Dudgeon, 2000; Lydeard et al., 2004; Strayer and Dudgeon, 2010; Burkhead, 2012; Haag and Williams, 2013). As such, their removal is a desirable and necessary component of stream restoration projects. Despite this general sentiment, there is a practical and financial need to prioritize among dams for removal and assess both the benefits and costs to stream ecosystems. Palmer et al. (2005) and others have called for standards to evaluate stream restoration success and specified five key traits of successful restoration projects. The first criterion they identified was that restoration must be guided by an image of a more dynamic, healthy river. Second, restoration should result in measurably improved stream condition and a more resilient self-sustaining system. Nearly all dam removal projects meet these criteria both inherently and quantitatively. In addition, Palmer et al. (2005) suggested that stream restoration should not cause irreparable harm to the ecosystem and that preand post-restoration monitoring data be made available to the public. While these may seem like eminently attainable and transparent goals, the reality is that financial restrictions limit the temporal scale of preand post-removal monitoring and restrict the ability to describe recovery intervals accurately, which may in turn impede an accurate assessment of the long-term effects of dam removals. Popular concepts of dam impacts are often focused, quite naturally, on their upstream effects on stream habitats. Dams transform free-flowing reaches to lentic habitats, restrict downstream sediment movement, and dramatically alter temperature, nutrient and productivity dynamics. Dams also alter downstream habitats and much work has documented physicochemical and biotic changes in downstream reaches. Much of what is known about dam impacts is derived from studies of high hydroelectric dams on large (i.e. >6th order) streams (Baxter, 1977; Graf, 2006). However, low-head dams (i.e. those <7.5m height) greatly exceed hydroelectric dams in number and thus affect a much broader range of stream sizes and ecosystem types (Graf, 1999; Csiki and Rhodes, 2010). Removing small dams has become a major part of stream and faunal restoration projects in North America. However, because so little is known about the effects of smaller dams on stream biota and ecosystems, obvious solutions may turn out to be problematic for other species. For example, because rivers across the globe have

Short-term effects of dam removal on macroinvertebrates in a Taiwan stream

Dam removal is an approach for restoring rivers. However, there are increasing concerns about the impact of removal on downstream biota. We examined the short-term responses of benthic macroinvertebrates and their avian predator (Brown Dipper, Cinclus pallasii Temminck) in reaches downstream of a check dam after it was removed from a mountain stream in central Taiwan. The density and taxonomic richness of downstream macroinvertebrates decreased immediately after dam removal. The decreases were associated with scouring or burial by sediments from the upstream impoundment. Ten weeks post-removal, downstream macroinvertebrate densities, although marginally recovering, remained lower than both pre-removal and upstream densities. Substantial changes in community structure were not significantly associated with an increase in the proportion of taxa with short life spans. However, this small-scale disturbance had no strong effect on the abundance of their very mobile, avian predator. This study and other studies of dam removal have found that downstream sedimentation following dam removal can reduce macroinvertebrate densities and that they may recover over time. Thus, timescale must be considered when interpreting the consequences of dam removal, especially when the long-term goal is stream restoration.

LONG‐TERM TAXON‐SPECIFIC RESPONSES OF MACROINVERTEBRATES TO DAM REMOVAL IN A MID‐SIZED SWEDISH STREAM

ABSTRACTDam removal to restore ecologically impaired rivers is becoming increasingly common. Although the target often is to facilitate fish migration, dam removal has also been assumed to benefit other types of organisms. Because few studies thus far deal with effects of dam removal on stream macroinvertebrates and because results have been equivocal, we investigated both short‐ and longer‐term dam‐removal effects on downstream macroinvertebrate communities. We did this in a before‐and‐after study of the removal of a dam located in a south Swedish stream. We sampled the benthic fauna 6 months before dam removal and both 6 months and 3.5 years after the dam was removed. We compared species composition, taxonomic richness, total densities and densities of macroinvertebrate groups before and after dam removal and between downstream and reference sites. We found that dam removal reduced some macroinvertebrate taxa at the downstream site, but we found no effect on community composition. Although this corroborates results from previous short‐term studies, we also found a reduction of taxonomic richness and that some dam‐removal effects persisted or even increased over time. The most likely explanation for the suppression of benthic macroinvertebrate richness following dam removal is a significantly increased sediment transport from the former reservoir and a subsequent loss of preferred substrates. Our results indicate that adverse dam‐removal effects may be long lasting but taxon specific. We therefore call for longer‐term studies on a variety of organisms to better understand how dam removal may influence downstream macroinvertebrate communities. Copyright © 2012 John Wiley &amp; Sons, Ltd.

A comparison of past small dam removals in highly sediment-impacted systems in the U.S.

The ability to predict the effects of dam removal in highly sediment-filled systems is increasingly important as the number of such dam removal cases continues to grow. The cost and potential impacts of dam removal are site-specific and can vary substantially depending on local conditions. Of specific concern in sediment-impacted removals is the volume and rate of reservoir deposit erosion. The complexity and potential accuracy of modeling methods used to forecast the effects of such dam removals vary substantially. Current methods range from predictions based on simple analysis of pre-dam channel geometry to sophisticated data-intensive, three-dimensional numerical models. In the work presented here, we utilize data collected from past dam removals to develop an additional tool for predicting the rate and volume of sediment deposit erosion. Through the analysis of sediment, discharge, deposit, removal timeline, channel, and watershed data, in conjunction with post-removal monitoring data from a wide range of dam removal projects, some significant trends in the evolution of reservoir deposits following dam removal can be seen. Results indicate that parameters such as median grain size, level of cohesion, spatial variability of the deposit, and removal timeline are among the most influential factors in determining the rate and volume of sediment erosion. By comparing local conditions of dams and reservoirs slated for removal with those of past removals, we hope that predictions of the rate and volume of sediment deposit erosion can be usefully constrained.

PHYSICAL AND PLANT COMMUNITY CONTROLS ON NITROGEN AND PHOSPHORUS LEACHING FROM IMPOUNDED RIVERINE WETLANDS FOLLOWING DAM REMOVAL

ABSTRACTDam removal has emerged as a critical issue in water resources engineering and management. Of particular concern in many regions of the USA is the effect of dam removal on downstream water quality and potential methods of decreasing sediment and nutrient loading to downstream reaches. Rapid revegetation of reservoir sediments has been suggested as a means of reducing the impact of dam removal, although little data exist about the role of vegetation in controlling the downstream release of sediment or nutrients.This study investigated an impounded riverine wetland complex on the Little River, North Carolina, before and after the removal of a low‐head dam. We quantified the leaching of interstitial nitrogen (N) and phosphorus (P) to the adjacent river channel during reservoir dewatering and, through experimental manipulations, isolated the difference between physical (soil) and biological (plant) controls on N and P leaching from dewatering impoundment sediments. We found that the rate and the quantity of N and P leaching from impounded dewatering sediment are predominately controlled by sediment porosity and specific yield. Although vegetation controls on N and P leaching were statistically significant during the first growing season following dam removal, vegetation is likely to be more important as a long‐term control on sediment and nutrient loads. Our results suggest that the initial release of N and P from a dewatered reservoir will be difficult to control but that vegetation may play an important long‐term role. Copyright © 2011 John Wiley &amp; Sons, Ltd.

Channel evolution on the dammed Elwha River, Washington, USA

Like many rivers in the western U.S., the Elwha River, Washington, has changed substantially over the past century in response to natural and human forcing. The lower river is affected by two upstream dams that are slated for removal as part of a major river restoration effort. In preparation for studying the effects of dam removal, we present a comprehensive field and aerial photographic analysis of dam influence on an anabranching, gravel-bed river. Over the past century with the dams in place, loss of the upstream sediment supply has caused spatial variations in the sedimentary and geomorphic character of the lower Elwha River channel. Bed sediment is armored and better sorted than on the naturally evolving bed upstream of the dams. On time scales of flood seasons, the channel immediately below the lower dam is fairly stable, but progresses toward greater mobility downstream such that the lowermost portion of the river responded to a recent 40-year flood with bank erosion and bed-elevation changes on a scale approaching that of the natural channel above the dams. In general, channel mobility in the lowest 4 km of the Elwha River has not decreased substantially with time. Enough fine sediment remains in the floodplain that – given sufficient flood forcing – the channel position, sinuosity, and braiding index change substantially. The processes by which this river accesses new fine sediment below the dams (rapid migration into noncohesive banks and avulsion of new channels) allow it to compensate for loss of upstream sediment supply more readily than would a dammed river with cohesive banks or a more limited supply of alluvium. The planned dam removal will provide a valuable opportunity to evaluate channel response to the future restoration of natural upstream sediment supply.

Lake Sturgeon Population Status and Demography in the Kettle River, Minnesota, 1992–2007

AbstractWe assessed population status and estimated selected demographic parameters for lake sturgeon Acipenser fulvescens in the Kettle River, Minnesota, using capture–recapture tagging data collected from 1992 to 2007. The lake sturgeon is an imperiled species of special concern in Minnesota, with population declines attributed to overfishing, pollution, and establishment of dams. In 1995, the recreational fishery was closed and the only dam on the Kettle River (Sandstone Dam) was removed, in part to promote lake sturgeon recovery. Recent incidental capture of lake sturgeon by anglers is prompting interest in re‐opening the recreational fishery. We gathered information to determine (1) status and demography of the Kettle River population, (2) the effect of dam removal, and (3) the feasibility of re‐opening the recreational fishery. Open‐population capture–recapture models were used to examine population status and estimate survival, seniority, and the relative importance of survival and recruitment for influencing population trends. The rate of population change (λ) indicated that the population was barely maintaining itself (average λ across years = 1.02; 95% confidence interval [CI] = 0.86–1.16). Annual population estimates ranged from about 130 fish to almost 300 fish but had wide CIs. Similarly, estimates of new lake sturgeon entering the population each year (either from within‐population recruitment or immigration) were variable and ranged from 0 to over 100. Annual survival was nearly constant at about 80%. Growth was slow relative to other populations but averaged about 28 mm/year for ages 6–21. A seniority parameter indicated that 49–87% of individuals in the population in a given year consisted of population members that survived from the previous year. This suggested that the population was essentially maintaining itself through a combination of episodic recruitment and relatively constant survival. Recent low recruitment may be due to a short‐term disturbance from sediment released when the dam was removed in 1995. Maintaining closure of the recreational fishery still appears necessary. Bolstering of recruitment may be needed to increase the population. Full recovery will require patience for this long‐lived, late‐maturing, infrequently reproducing species.

Managing reservoir sediment release in dam removal projects: An approach informed by physical and numerical modelling of non‐cohesive sediment

Sediment management is frequently the most challenging concern in dam removal but there is as yet little guidance available to resource managers. For those rivers with beds composed primarily of non‐cohesive sediments, we document recent numerical and physical modelling of two processes critical to evaluating the effects of dam removal: the morphologic response to a sediment pulse, and the infiltration of fine sediment into coarser bed material. We demonstrate that (1) one‐dimensional numerical modelling of sediment pulses can simulate reach‐averaged transport and deposition over tens of kilometres, with sufficient certainty for managers to make informed decisions; (2) physical modelling of a coarse sediment pulse moving through an armoured pool‐bar complex shows deposition in pool tails and along bar margins while maintaining channel complexity and pool depth similar to pre‐pulse conditions; (3) physical modelling and theoretical analysis show that fine sediment will infiltrate into an immobile coarse channel bed to only a few median bed material particle diameters. We develop a generic approach to sediment management during dam removal using our experimental understanding to guide baseline data requirements, likely environmental constraints, and alternative removal strategies. In uncontaminated, non‐cohesive reservoir sediments we conclude that the management impacts of rapid sediment release may be of limited magnitude in many situations, and so the choice of dam removal strategy merits site‐specific evaluation of the environmental impacts associated with a full range of alternatives.

Assessing Sediment‐Related Effects of Dam Removals: Subcommittee on Sedimentation: Sediment Management and Dam Removal Workshop; Portland, Oregon, 14–16 October 2008

For a host of reasons including dam safety, maintenance costs, and ecological concerns, more dams are currently being removed each year in the United States than are being constructed. Because many reservoirs have accumulated sediments within their pools, dam removal can potentially impose a variety of sediment‐related risks, including downstream effects on habitat, water quality, infrastructure, and flood storage. Sediment‐related risks are particularly heightened when the sediment stored behind a dam is contaminated.

Influence of Small Dams on Downstream Channel Characteristics in Pennsylvania and Maryland: Implications for the Long‐Term Geomorphic Effects of Dam Removal1

Abstract: We evaluate the effects of small dams (11 of 15 sites less than 4 m high) on downstream channels at 15 sites in Maryland and Pennsylvania by using a reach upstream of the reservoir at each site to represent the downstream reach before dam construction. A semi‐quantitative geomorphic characterization demonstrates that upstream reaches occupy similar geomorphic settings as downstream reaches. Survey data indicate that dams have had no measurable influence on the water surface slope, width, and the percentages of exposed bedrock or boulders on the streambed. The median grain diameter (D50) is increased slightly by dam construction, but D50 remains within the pebble size class. The percentage of sand and silt and clay on the bed averages about 35% before dam construction, but typically decreases to around 20% after dam construction. The presence of the dam has therefore only influenced the fraction of finer‐grained sediment on the bed, and has not caused other measurable changes in fluvial morphology. The absence of measurable geomorphic change from dam impacts is explicable given the extent of geologic control at these study sites. We speculate that potential changes that could have been induced by dam construction have been resisted by inerodible bedrock, relatively immobile boulders, well‐vegetated and cohesive banks, and low rates of bed material supply and transport. If the dams of our study are removed, we argue that long‐term changes (those that remain after a period of transient adjustment) will be limited to increases in the percentage of sand and silt and clay on the bed. Thus, dam removal in streams similar to those of our study area should not result in significant long‐term geomorphic changes.

Using historic aerial photography and paleohydrologic techniques to assess long-term ecological response to two Montana dam removals

The restorative potential of dam removal on ecosystem function depends on the reversibility of dam effects and its operations. While dam removal is an established engineering practice, the need for an understanding of the ecological response remains. We used paleoflood hydrology, hydrologic modeling, and aerial photo interpretation to investigate the long-term ecologic responses to dam failure and breach. We investigated downstream geomorphic and vegetation responses to a dam failure (Pattengail Dam in 1927) and a controlled dam breach, which used natural sediment removal (Mystic Lake Dam in 1985). Our data showed vegetation responses indicative of channel and floodplain evolution at Pattengail. The size of the flood following the Pattengail dam failure initiated a series of channel adjustments and reworked over 19 ha of floodplain downstream of the dam. In Mystic, we observed few flood stage indicators and a slight response in floodplain vegetation. We made several findings. (1) Dam removal effects on channel evolution and floodplain development depend on reach types and their responsiveness to flow regime change. (2) Ecologic response to dam removal depends on the sizes and timing of high flow events during and following removal. (3) Paleohydrology can be used to assess historic floods (>20 years). We see the utility of assessing the ecological responsiveness of a system to previous fluvial events or changes in flow regime. Informed about the character of a system based on its history, dam removal scientists can use these tools to set realistic restoration goals for removing a dam.