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177 result(s) for "Stream restoration -- United States"
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Fields and Streams
Examining the science of stream restoration, Rebecca Lave argues that the neoliberal emphasis on the privatization and commercialization of knowledge has fundamentally changed the way that science is funded, organized, and viewed in the United States.Stream restoration science and practice is in a startling state. The most widely respected expert in the field, Dave Rosgen, is a private consultant with relatively little formal scientific training. Since the mid-1990s, many academic and federal agency-based scientists have denounced Rosgen as a charlatan and a hack. Despite this, Rosgen's Natural Channel Design approach, classification system, and short-course series are not only accepted but are viewed as more legitimate than academically produced knowledge and training. Rosgen's methods are now promoted by federal agencies including the Environmental Protection Agency, the U.S. Forest Service, the U.S. Fish and Wildlife Service, and the Natural Resources Conservation Service, as well as by resource agencies in dozens of states.Drawing on the work of Pierre Bourdieu, Lave demonstrates that the primary cause of Rosgen's success is neither the method nor the man but is instead the assignment of a new legitimacy to scientific claims developed outside the academy, concurrent with academic scientists' decreasing ability to defend their turf. What is at stake in the Rosgen wars, argues Lave, is not just the ecological health of our rivers and streams but the very future of environmental science.
River republic
Daniel McCool not only chronicles the history of water development agencies in America and the way in which special interests have abused rather than preserved the country's rivers, he also narrates the second, brighter act in this ongoing story: the surging, grassroots movement to bring these rivers back to life and ensure they remain pristine for future generations. The culmination of ten years of research and observation, McCool's book confirms the surprising news that America's rivers are indeed returning to a healthier, free-flowing condition. The politics of river restoration demonstrates how strong grassroots movements can challenge entrenched powers and win. Through passion and dedication, ordinary people are reclaiming the American landscape, forming a \"river republic\" of concerned citizens from all backgrounds and sectors of society. As McCool shows, the history, culture, and fate of America is tied to its rivers, and their restoration is a microcosm mirroring American beliefs, livelihoods, and an increasing awareness of what two hundred years of environmental degradation can do. McCool profiles the individuals he calls \"instigators,\" who initiated the fight for these waterways and, despite enormous odds, have succeeded in the near-impossible task of challenging and changing the status quo. Part I of the volume recounts the history of America's relationship to its rivers; part II describes how and why Americans \"parted\" them out, destroying their essence and diminishing their value; and part III shows how society can live in harmony with its waterways while restoring their well-being—and, by extension, the well-being of those who depend on them.
Recovering a lost river : removing dams, rewilding salmon, revitalizing communities
Author's argument that the best hope for the Snake River lies in dam removal, a solution that pits the power companies and federal authorities against a collection of Indian tribes, farmers, fishermen, and river recreationists.
Assessing stream restoration effectiveness at reducing nitrogen export to downstream waters
The degradation of headwater streams is common in urbanized coastal areas, and the role these streams play in contributing to downstream pollution is a concern among natural resource managers and policy makers. Thus, many urban stream restoration efforts are increasingly focused on reducing the downstream flux of pollutants. In regions that suffer from coastal eutrophication, it is unclear whether stream restoration does in fact reduce nitrogen (N) flux to downstream waters and, if so, by how much and at what cost. In this paper, we evaluate whether stream restoration implemented to improve water quality of urban and suburban streams in the Chesapeake Bay region, USA, is effective at reducing the export of N in stream flow to downstream waters. We assessed the effectiveness of restored streams positioned in the upland vs. lowland regions of Coastal Plain watershed during both average and stormflow conditions. We found that, during periods of low discharge, lowland streams that receive minor N inputs from groundwater or bank seepage reduced in-stream N fluxes. Furthermore, lowland streams with the highest N concentrations and lowest discharge were the most effective. During periods of high flow, only those restoration projects that converted lowland streams to stream-wetland complexes seemed to be effective at reducing N fluxes, presumably because the design promoted the spillover of stream flow onto adjacent floodplains and wetlands. The observed N-removal rates were relatively high for stream ecosystems, and on the order of 5% of the inputs to the watershed. The dominant forms of N entering restored reaches varied during low and high flows, indicating that N uptake and retention were controlled by distinctive processes during different hydrological conditions. Therefore, in order for stream restoration to effectively reduce N fluxes exported to downstream waters, restoration design should include features that enhance the processing and retention of different forms of N, and for a wide range of flow conditions. The use of strategic designs that match the dominant attributes of a stream such as position in the watershed, influence of groundwater, dominant flow conditions, and N concentrations is crucial to assure the success of restoration.
Survey of Beaver-related Restoration Practices in Rangeland Streams of the Western USA
Poor condition of many streams and concerns about future droughts in the arid and semi-arid western USA have motivated novel restoration strategies aimed at accelerating recovery and increasing water resources. Translocation of beavers into formerly occupied habitats, restoration activities encouraging beaver recolonization, and instream structures mimicking the effects of beaver dams are restoration alternatives that have recently gained popularity because of their potential socioeconomic and ecological benefits. However, beaver dams and dam-like structures also harbor a history of social conflict. Hence, we identified a need to assess the use of beaver-related restoration projects in western rangelands to increase awareness and accountability, and identify gaps in scientific knowledge. We inventoried 97 projects implemented by 32 organizations, most in the last 10 years. We found that beaver-related stream restoration projects undertaken mostly involved the relocation of nuisance beavers. The most common goal was to store water, either with beaver dams or artificial structures. Beavers were often moved without regard to genetics, disease, or potential conflicts with nearby landowners. Few projects included post-implementation monitoring or planned for longer term issues, such as what happens when beavers abandon a site or when beaver dams or structures breach. Human dimensions were rarely considered and water rights and other issues were mostly unresolved or addressed through ad-hoc agreements. We conclude that the practice and implementation of beaver-related restoration has outpaced research on its efficacy and best practices. Further scientific research is necessary, especially research that informs the establishment of clear guidelines for best practices.
A stream classification system to explore the physical habitat diversity and anthropogenic impacts in riverscapes of the eastern United States
Describing the physical habitat diversity of stream types is important for understanding stream ecosystem complexity, but also prioritizing management of stream ecosystems, especially those that are rare. We developed a stream classification system of six physical habitat layers (size, gradient, hydrology, temperature, valley confinement, and substrate) for approximately 1 million stream reaches within the Eastern United States in order to conduct an inventory of different types of streams and examine stream diversity. Additionally, we compare stream diversity to patterns of anthropogenic disturbances to evaluate associations between stream types and human disturbances, but also to prioritize rare stream types that may lack natural representation in the landscape. Based on combinations of different layers, we estimate there are anywhere from 1,521 to 5,577 different physical types of stream reaches within the Eastern US. By accounting for uncertainty in class membership, these estimates could range from 1,434 to 6,856 stream types. However, 95% of total stream distance is represented by only 30% of the total stream habitat types, which suggests that most stream types are rare. Unfortunately, as much as one third of stream physical diversity within the region has been compromised by anthropogenic disturbances. To provide an example of the stream classification's utility in management of these ecosystems, we isolated 5% of stream length in the entire region that represented 87% of the total physical diversity of streams to prioritize streams for conservation protection, restoration, and biological monitoring. We suggest that our stream classification framework could be important for exploring the diversity of stream ecosystems and is flexible in that it can be combined with other stream classification frameworks developed at higher resolutions (meso- and micro-habitat scales). Additionally, the exploration of physical diversity helps to estimate the rarity and patchiness of riverscapes over large region and assist in conservation and management.
Effects of stream restoration by legacy sediment removal and floodplain reconnection on water quality
The effectiveness of many stream restorations in improving water quality is unmeasured. In the Mid-Atlantic region of the United States, activity by European settlers resulted in upland erosion and deposition of sediments 1-3 m in thickness in stream valleys. Subsequently, streams incised those legacy sediments creating steep, exposed banks, infrequent floodplain inundation, and water tables disconnected from floodplains. Legacy sediment removal (LSR) and floodplain reconnection (FR) proposes water quality improvement by restoration to a hydrological state closer to pre-European. We investigated water quality at nine sites, six restored with LSR/FR and three comparison sites. Nitrogen baseflow concentrations and fluxes were elevated in urban and agricultural watersheds with little apparent effect due to restoration. Denitrification appeared to be constrained by carbon availability. Ion concentrations were elevated in all watersheds compared to a forested reference and represent a substantial ecological stressor for the post-restoration aquatic community. Storm event data from one site suggest small reductions in nutrient and sediment loads across the restored reach. High-frequency time series indicate that restoration effects are not observable at larger scales. The effects of restoration, particularly for denitrification, may not be observable for years and can be obscured by weather and climate-driven variability.
Stream Conditions after 18 Years of Passive Riparian Restoration in Small Fish-bearing Watersheds
Many of the ecological processes in the riparian forests and streams across the Pacific Northwest have become impaired through production forestry practices common prior to the 1990s. Some of these practices included forest harvest without stream buffers, removal of instream wood, road construction and use, and harvesting large proportions of watersheds. Passive ecological restoration (the use of natural processes of succession and disturbance to alleviate anthropogenic impacts over time) is a common practice used in the management of riparian forests previously subjected to production forestry. Eighteen years after the implementation of passive restoration of riparian forests, we used four common stream indicators (stream temperature, canopy closure, instream wood, and salmonid densities) to assess the effects of restoration in small fish-bearing streams. Summer stream temperatures have decreased below unmanaged reference levels, whereas riparian forest canopy closure has increased beyond that in reference watersheds. Instream wood and age-1 or older salmonids appear to be either stable at reduced levels or declining, compared with production forestry and unmanaged reference watersheds. Overall, second-growth riparian forests need more time to develop allowing more light into streams (increasing primary productivity), while also allowing for the continuous recruitment of larger pieces of instream wood (improving habitat for salmonids). Using only passive restoration, stream conditions in second-growth forests are unlikely to increase salmonid production in the near future.
Unearthing a stream-wetland floodplain system: increased denitrification and nitrate retention at a legacy sediment removal restoration site, Big Spring Run, PA, USA
Nitrogen (N) retention is a common goal of stream-wetland restoration projects in systems with excess nitrate (NO3−), however N retention depends on habitats with high denitrification and uptake rates that interact with NO3−. Legacy sediments deposited along formerly impounded streams bury and disconnect historic floodplain-wetland systems. This disconnection limits sediment-water interactions, decreases N retention and increases N delivery. Restoration with legacy sediment removal should lead to greater N retention due to the reestablishment of wet habitats that interact with NO3−-rich water, but the formation of biogeochemically retentive soils under modern conditions of high NO3−, N retention rates, and recovery time are unclear. An experimental restoration approach undertaken at Big Spring Run in Lancaster, PA, USA was used to test the hypothesis that reconnection of a stream to its historic floodplain with legacy sediment removal enhances N processing and retention. We describe changes in sediment and water concentrations of N and organic carbon (C) along with the changes in sediment biogeochemical processing rates of denitrification, nitrification, and C mineralization, before and for five years following restoration. Our results show that biogeochemical processing increased and higher NO3− retention developed following stream-wetland restoration. NO3− retention improved after several years as organic matter accumulated to ultimately support higher rates of denitrification that transitioned from organic C limitation to NO3− limitation. We conclude that, in systems with high contemporary NO3−, restoration via legacy sediment removal and floodplain reconnection can lead to the accumulation of organic matter and improved biogeochemical NO3− retention over time
A process-based assessment of landscape change and salmon habitat losses in the Chehalis River basin, USA
Identifying necessary stream and watershed restoration actions requires quantifying natural potential habitat conditions to diagnose habitat change and evaluate restoration potential. We used three general methods of quantifying natural potential: historical maps and survey notes, contemporary reference sites, and models. Historical information was available only for the floodplain habitat analysis. We used contemporary reference sites to estimate natural potential habitat conditions for wood abundance, riparian shade, main channel length, and side channel length. For fine sediment, temperature, and beaver ponds we relied on models. We estimated a 90% loss of potential beaver pond area, 91% loss of side-channel length, and 92% loss or degradation of floodplain marshes and ponds. Spawning habitat area change due to wood loss ranged from -23% to -68% across subbasins. Other changes in habitat quantity or quality were smaller—either in magnitude or spatial extent—including rearing habitat areas, stream temperature, and accessible stream length. Historical floodplain habitat mapping provided the highest spatial resolution and certainty in locations and amounts of floodplain habitat lost or degraded, whereas use of the contemporary reference information provided less site specificity for wood abundance and side-channel length change. The models for fine sediment levels and beaver pond areas have the lowest reach-specific certainty, whereas the model of temperature change has higher certainty because it is based on a detailed riparian inventory. Despite uncertainties at the reach level, confidence in subbasin-level estimates of habitat change is moderate to high because accuracy increases as data are aggregated over multiple reaches. Our results show that the largest habitat losses were floodplain and beaver pond habitats, but use of these habitat change results in salmon life-cycle models can illustrate how the potential benefits of alternative habitat restoration actions varies among species with differing habitat preferences.