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Low-Tech Process-Based Restoration of Riverscapes: Design Manual. Version 1.0
Abstract
The purpose of this design manual is to provide restoration practitioners with guidelines for implementing a subset of low-tech tools —namely beaver dam analogues (BDAs) and post-assisted log structures (PALS)—for initiating process-based restoration in structurally-starved riverscapes. While the concept of process-based restoration in riverscapes has been advocated for at least two decades, details and specific examples on how to implement it remain sparse. Here, we describe ‘low-tech process-based restoration’ (LT-PBR) as a practice of using simple, low unit-cost, structural additions (e.g. wood and beaver dams) to riverscapes to mimic functions and initiate specific processes. Hallmarks of this approach include:
- An explicit focus on the processes that a low-tech restoration intervention is meant to promote
- A conscious effort to use cost-effective, low-tech treatments (e.g. hand-built, natural materials, non-engineered, short-term design life-spans) because of the need to efficiently scale-up application.
- ‘Letting the system do the work’ which defers critical decision making to riverscapes and nature’s ecosystem engineers.
Other resources available at: http://lowtechpbr.restoration.usu.edu
... Yet, due to the persistence of water and associated plant communities that drive recovery after disturbance, riparian areas are inherently resilient. With active restoration, the potential land that could support riparian conditions may be several times larger than the current footprint (Wheaton et al. 2019a;Macfarlane et al. 2018). ...
... Biology-especially in the form of vegetation Types of riparian areas embedded within rangeland watersheds. Riparian areas are rare but diverse ecosystems that occur along river and stream corridors, meadows and bogs, springs and seeps, wetlands, and lakes and North American beaver (Castor canadensis)-also interacts with physical conditions to shape riparian form and function (Castro and Thorne 2019;Wheaton et al. 2019a). From a hydrologic standpoint, riparian systems are the interface between open water bodies (channels and ponds) and land connected through surface or subsurface flow (Wilcox et al. 2017). ...
... On rangelands, the bulk of riparian areas are associated with fluvial systems, such as streams and rivers. Best viewed as riverscapes, stream and riverine landscapes are composed of floodplains and channels that together comprise the valley bottom (Fig. 7.2, Ward 1998;Wheaton et al. 2019a). The valley bottom reflects the maximum possible extent that could be occupied by riparian vegetation. ...
Water scarcity and climatic variability shape human settlement patterns and wildlife distribution and abundance on arid and semi-arid rangelands. Riparian areas-the transition between water and land-are rare but disproportionately important habitats covering just a fraction of the land surface (commonly < 2% in the western U.S.). Riparian areas provide critical habitat for fish and other aquatic species, while also supporting the vast majority (70-80%) of terrestrial wildlife during some portion of their life cycle. Diverse riparian types serve as vital sources of water and late summer productivity as surrounding uplands dry during seasonal drought. The health and function of rangeland riparian systems are closely tied to hydrology, geomorphology, and ecology. Riparian areas have attracted intense human use resulting in their widespread degradation. Conservation actions, including improved livestock grazing management and restoration, can help maintain and enhance riparian resilience to drought, wildfire, and flooding. This chapter provides readers with an introduction to the importance of riparian areas in rangelands, their nature and ecology, functions for wildlife, and prevailing management and restoration approaches.
... Proposed restoration activities include a combination of techniques to reconnect incised stream channels with the meadow floodplain focused on restoring the hydrologic function of the meadow ecosystems and restoring diverse instream habitat components that benefit fish and other aquatic organisms. Restoration of project site meadows will largely rely on low-tech process-based restoration (LTPBR) techniques (Wheaton et al. 2019) to address meadow impairments such as head-cutting and channel incision. LTPBR relies heavily on using hand-built structures to amplify hydraulics to initiate geomorphic processes of erosion and deposition that increases vertical and lateral hydrologic connectivity. ...
... For detailed site descriptions for each meadow project site can be found in the Conceptual Design Plan. (Wheaton et al. 2019). Disrupted and impacted meadow ecosystems suffer from floodplain disconnection, vegetation community conversion from hydric and mesic meadow species such as obligate and facultative wetland plant communities (sedges, rushes, aquatic grasses, and willow) with little exposed soil and high concentrations of organic materials to xeric upland communities dominated by sagebrush and annual grasses with significant amounts of bare, exposed soil and loss of carbon storage potential (Viers et al. 2013). ...
... This will likely be most successful in areas where there is less than 1 m of incision between the historical floodplain and the current bankfull indicator (Allen Diaz 1991, Castelli et al. 2000, Debinski et al. 2010. These areas will likely respond quickly to phase 1 treatments with the increase in streambed elevation created by restoration structures such as Beaver Dam Analogs (BDAs), which will instantaneously lift water table elevations, increase instream water storage, and increase hyporheic exchange and groundwater recharge thus cooling and filtering water, aiding in sediment deposition and streambed aggradation, and helping to retain heavy sediment loads within depositional landscape features (Wheaton et al. 2019). ...
This report is the monitoring plan to evaluate responses of Kern Plateau meadows to Low-Tech Process-Based Restoration described in the Final Kern Meadows Restoration Design. The documented was prepared for and edited by Trout Unlimited, with funding from California Department of Fish and Wildlife.
... The last tool in restoring riparian function is direct channel intervention. The focus of this is low-tech, process-based restoration (PBR), with structures made from wood or rock established within the stream channel [59,60]. Other structures such as beaver dam analogs can be used and mimic physical and ecological benefits created by natural beaver dams such as slowing and capturing runoff and allowing water on the landscape to infiltrate into the soil [53]. ...
... Over time, as water is slowed and sediment builds up, the streams can access disconnected floodplains and/or establish new ones [53]. Ultimately, the goal of PBR is to "let the water do the work" [59,60]. ...
Small (<15 m wide), intermittent prairie streams in western South Dakota, a semiarid part of the northern United States, are undervalued ecosystems because they do not exemplify the values of classic, flowing streams. However, they are valuable as wildlife corridors, aquatic habitat for drought-adapted species, and support of local grazing economies. We surveyed 90 streams in 2018–2019, collecting data on geomorphic, water chemistry, and biological properties, focusing on vegetation and grazing impacts. We developed an approach for categorizing streams by landscape position and flow regime to facilitate appropriate land management and stream restoration actions. The result was a published landowner guide to provide information on low-tech riparian management and restoration options of the four stream types we categorized. The headwaters streams and woody draws with drainage areas <26 km2 are the most abundant types and exemplify the issues described above. Large rivers, despite drainage areas exceeding 260 km2 can go dry. Management issues include invasive plant species, lack of woody riparian establishment, poor water quality, overgrazing, channel incision, and water stress from climate change. The most cost-effective management practices involve rotational grazing and practices that reduce cattle impacts. More recently, beaver dam analogs have been installed and beaver reintroduction is being considered along with reestablishment of native bison herds in place of cattle. Intermittent prairie streams present an excellent case study of an undervalued ecosystem, illustrating the challenges and opportunities of such systems. Engagement of grazing landowners can improve stewardship of these systems.
... Simultaneously, in some systems they can interfere with infrastructure (Albert and Trimble 2000) and provide habitat that can be beneficial for non-native fishes (Gibson et al. 2015). Historical removal of beavers from across North America, and a growing recognition of the benefits they provide, has led to a dramatic upswing in the use of beaver restoration and mimicry to restore degraded ecosystems (McKinstry and Anderson 2002, Pilliod et al. 2018, Wheaton et al. 2019. Beaver dam analogs (BDAs) are being widely deployed to aggrade streams and improve habitat for beaver recolonization in systems where beaver extirpation has occurred (Pollock et al 2014, Pilliod et al. 2018). ...
Beaver (Castor canadensis) translocation and mimicry is an increasingly popular set of tools for process-based restoration of degraded streams. Previous studies indicate that spring-spawning salmonid fishes can pass beaver dams in higher proportions than fall-spawning species. Thus, restoration or mimicry of beavers in streams containing threatened, fall-spawning bull trout (Salvelinus confluentus) is of concern to many biologists. We evaluated bull trout passage at beaver dams in two Montana streams: Meadow Creek (East Fork Bitterroot River drainage) in summer 2020 and Morrison Creek (Middle Fork Flathead River drainage) from 1997 to 2011. In Meadow Creek, 16% of PIT-tagged bull trout which entered a large beaver dam complex were detected upstream of some dams, but no fish moved through the entire 1 km complex. The redds in Morison Creek occurred below beaver dams in higher proportion than if random spawning-site selection had occurred. Redds were found above some beaver dams during all 9 years dams were present. These results suggest that beaver dams can affect the movement of bull trout and that passage depends on the characteristics of individual dams and reach geomorphology, though our methods cannot distinguish between inhibition of fish movement and selection of beaver-created habitats by fish due to the limited data we had on spawning habitat. Therefore, we suggest future beaver restoration in streams with bull trout be carefully monitored and conducted in an adaptive framework. Comparing spawning-site selection and fish movement in streams with and without beavers may provide additional information.
... Historic homesteads in the Kawuneeche Valley still contain ditches affecting water table depths. Identifying and remedying such hydrological constraints through active restoration approaches like simulated beaver structures may be useful to accelerate willow height and cover trends (Pollock et al. 2014;Weber et al. 2017;Wheaton et al. 2019). RMNP is currently evaluating the suitability of simulated beaver structures for habitat restoration. ...
... Hydrologic restoration also has greater potential to improve water quality than conventional in-stream restoration, although projects that combine both habitat restoration and stormwater management may show the largest benefits in water quality (Lammers et al. 2020). By extension, Hawley (2022) suggests that even simple habitat restoration strategies such as riparian reforestation, invasive species removal, and hand-placement of in-stream wood (Wheaton et al. 2019;Hawley 2018) could further enhance the geomorphic, habitat, and ecological benefits of hydrologic-based restoration interventions. These hydrological and habitat improvements associated with flow-based restoration can have a monetary value via stream mitigation credits, providing a potential funding source for more comprehensive hydrologic restoration efforts in urban watersheds (Hawley 2022). ...
Urban stream restoration is growing globally, but there is much to learn from successes, failures, and evaluating tradeoffs in restoration practices. Significant time and resources have been invested towards restoring the structure and function of urban ecosystems and understanding and slowing the drivers of degradation. However, the rapid pace of urbanization and its effects on urban waters present an ever-growing challenge to environmental managers and restoration practitioners when identifying and prioritizing effective strategies for restoration and monitoring outcomes. Here, we synthesize major findings and papers originating from the 5th Symposium on Urbanization and Stream Ecology (SUSE5) and propose a new concept for monitoring restoration based on lessons learned. Efforts from SUSE5 showed that urban disturbances and restoration activities have strong localized impacts that can be challenging to detect and disentangle across broader watershed scales and longitudinal flowpaths. Most urban stream restoration projects are monitored at only one or a few locations that do not capture significant variability across stream reaches and longer flowpaths. Based on knowledge from SUSE5, we present a new concept called ‘restoration milestones.’ The restoration milestones concept proposes that the scale of stream monitoring over space and time can influence whether a stream restoration project is considered a success or failure. Therefore, answers to questions regarding restoration effectiveness and durability can be affected by spatial and temporal monitoring scales. Setting realistic restoration milestones involves establishing monitoring strategies that account for spatial and temporal variability. Tracking restoration performance through time across stream reaches along longitudinal flowpaths could aid in more accurately assessing project performance. We explore applications for evaluating restoration milestones along longitudinal stream flowpaths including: (1) identifying target areas of improvement along drainage networks, (2) accurately accounting for tradeoffs in habitat, protection of infrastructure, and water quality along flowpaths, and (3) detecting how far downstream the effects of stream restoration and stormwater management can be propagated. Monitoring across different spatial and temporal scales is an overlooked but critical factor in determining restoration success. Additionally, the scale of the restoration project itself can determine the type and magnitude of improvements. Expectations for what a restoration project can accomplish in terms of water quality improvements should be calibrated to the project’s spatial scale and evolution over time. Longitudinal studies of stream restoration help identify successes and failures along flowpaths.
... Evolving thought structures and practices among stream specialists have recently trended in the direction of intentionally supporting relatively dynamic systems, and a growing number of alternatives to stable channel design are gaining traction (e.g., Beardsley & Boyd, 2019). Self-forming channels (Mecklenburg, 2008), Stage 0 restoration (e.g., Powers et al., 2019), and low-tech process-based restoration (Wheaton et al., 2019) are examples of dynamic approaches that leave design decisions to the system rather than dictating natural processes through constructed channels, and they may generate greater benefits in terms of water quality and ecosystem resilience (e.g., Cluer & Thorne, 2014). However, the most naturally dynamic approaches to stream restoration may not be suitable where constraints generally dictate the use of stable channel design, particularly sites with corridor encroachments common to transportation projects and highly urban settings (Kondolf, 2011). ...
Natural channel design (NCD) and analytical channel design (ACD) are two competing approaches to stable channel design that share fundamental similarities in accounting for sediment transport processes with designs based on hybrid fluvial geomorphology and hydraulic engineering methods. In this paper, we highlight the linkage between ACD's capacity/supply ratio (CSR) and NCD's sediment capacity models (FLOWSED/POWERSED), illustrating how ACD and NCD have reached a point of convergent evolution within the stream restoration toolbox. We modified an existing CSR analytical spreadsheet tool which enabled us to predict relative channel stability using both conventional bed load transport equations and regional sediment regression curves. The stable channel design solutions based on measured data most closely matched the Parker (ACD) and/or Pagosa good/fair (NCD) relationships, which also showed the greatest CSR sensitivity in response to channel alterations. We found that CSR differences among the transport relationships became more extreme the further the design width deviated from the supply reach, suggesting that a stable upstream supply reach may serve as the best design analog. With this paper, we take a step toward resolving lingering controversy in the field of stream restoration, advancing the science and practice by reconciling key differences between ACD and NCD in the context of reach scale morphodynamics.
Groundwater systems in snow-dominated drainage areas supply cool baseflows that support instream and downstream users late into the dry season. Yet, these catchments are becoming rarer with climate change and anthropogenic pressures that threaten groundwater systems. Restoration of low-gradient meadows and streams can recover a catchment’s natural storage potential, especially in Mediterranean biomes such as the Sierra Nevada of California where summer groundwater recharge is scarce. The degradation of meadows due to intense human modification has decreased groundwater elevations and shifted wet meadow plant communities toward more xeric forest and shrub communities. We applied machine learning tools to find potential “lost meadows” that may no longer support high groundwater elevations or meadow vegetation but do exhibit basic geomorphic and climatic characteristics similar to existing meadows. The model reveals potential meadow habitat in the Sierra Nevada of nearly three times its current extent. We offer two conceptual applications of the model for incorporating meadows in watershed restoration planning. The first application focuses on strategically expanding wet meadows already associated with fuel breaks for increasing wildfire resistance. The second shows how meadow restoration in post-wildfire landscapes could increase capture of sediment from burned hillslopes where increased sediment storage would benefit water storage. Meadows are important habitats that have become degraded due to long-term overuse. Re-envisioning their potential extent shows that, with restoration, meadows could also serve as components of California’s multi-tiered efforts to manage pressing threats to its forests and water supply.
Beaver are ecosystem engineers capable of converting free‐flowing lotic habitats into a series of lentic ponds, thereby enhancing the wetland area of a riverscape. Process‐based riverscape restoration using beaver reintroductions and mimicry (beaver dam analogues, BDAs) are increasingly used to restore functions, the provisioning of services, and improve the resiliency of ecosystems across North America and Europe. Beaver can create breeding habitat for a wide range of species within the highly imperilled class Amphibia by increasing wetland area, increasing emergent vegetation, prolonging wetland hydroperiod, and creating deep ponds. However, it remains unclear whether BDAs are creating suitable breeding habitat for amphibians by adequately emulating crucial ecosystem processes. We investigated the relationships between beaver dam and BDA complexes with amphibian breeding occupancy across four catchments feeding the Great Salt Lake, U.S.A. We surveyed 24 beaver dam complexes and nine BDA complexes during the 2019–2021 breeding seasons with varying levels of water availability. We compared environmental characteristics between beaver and BDA complexes, including elevation, depth, and fish relative abundance among others. We then used occupancy models to evaluate factors affecting breeding occupancy of the most frequently encountered amphibian species, barred tiger salamanders (Ambystoma mavortium). Without accounting for imperfect detection, at natural beaver ponds we recorded barred tiger salamanders in 58% of sites, boreal chorus frogs (Pseduarcris maculata) at 17% of sites, and northern leopard frogs (Lithobates pipens) at 4% of sites. Tiger salamanders were the only amphibian found at BDA sites, occupying 11% of those sites. We found that beaver complexes had 3 times less fish relative abundance, were 250m higher in elevation, 32 years older, and 0.43 m deeper than their BDA counterparts. Meanwhile, emergent vegetation height, water temperature, and hydroperiod demonstrated no significant differences between site types. BDAs modified ecosystem processes in a way that only partially replicated modifications by natural beaver dams. Occupancy models suggested that fish relative abundance, altitude, age, and being at the top of the drainage network were the most important variables for predicting tiger salamander breeding occupancy. Overall occupancy rate of tiger salamanders was 60%, while BDA complexes had a modelled occupancy rate of 14% compared to 78% in natural beaver complexes. Survey year did not appear to be an important factor in tiger salamander occupancy despite varying levels of water availability. Beaver and BDA complexes located near the top of their effective drainage or tributary junctions appeared to support amphibian along with fish species, thus boosting local diversity relative to a stream with only fish species. We therefore suggest future beaver restoration efforts target the top of effective drainages to benift both taxa. Overall, we found that while BDAs have the capacity to provide amphibian habitat, their younger age and higher fish abundance may explain why they are less effective than natural dams. Managers should therefore consider that the effects of restoration with BDAs may not be immediate, and future maintenance may be required.
Nature-based Solutions (NbS) are gaining momentum as potential solutions to restore, preserve and enhance ecosystem services for societal challenges, in general. In particular they improve ecological, social and economic urban resilience. As nature provides structure and carries out functions in NbS, from a designer's perspective, it is beneficial to explore and understand the strategies and mechanisms that living systems deploy to carry out those functions (ecosystem services) we are looking for. To date, exploration of the biological and ecological domains has mainly been instrumental in answering the question: how does nature provide ecosystem services? This type of broad inquiry, however, may not allow the identification of best practices to set up successful NbS projects. What if the question was: how would nature design and implement NbS? This inquiry falls within the domain of biomimicry. This work mainly aims at introducing the benefits that biomimicry or a biologically-inspired design (BID) approach could bring to address technological barriers and knowledge gaps currently hampering NbS diffusion. The work starts by clarifying if and how bio-inspiration is embedded within the main definitions of NbS (which also lead to determining the official definition of NbS by the European Commission). Furthermore, initial elements are provided to apply a bio-inspired approach to NbS. The approach is demonstrated on three levels:
i)Formulation of broad principles/guidelines for NbS (based on Life Principles);
ii)Generation of bio-inspired ideas (for green-grey, blue-green infrastructure) and identification of existing bio-inspired solutions which could improve various phases of the NbS project cycle (through multiple inquiries in Asknature.org); and
iii)Indication of on-going biomimetic research and development, which could assist in innovating NbS.
As the scientific literature seems rather dry on this specific topic, this work, far from being exhaustive, aims to contribute to kick-starting the missing dialogue surrounding NbS and bio-inspiration; a dialogue among the scientific community, as well as among all the actors involved in the NbS project cycle.
The Low-Tech Process Based Restoration of Riverscapes Pocket Guide is an illustrated and condensed version of the Design Manual (http://lowtechpbr.restoration.usu.edu). The pocket guide is designed to fit in your pocket (4 x 6") to use as a reference in the field.
Chapter Four of Low-Tech Process-Based Restoration of Riverscapes: Design Manual (http://lowtechpbr.restoration.usu.edu
Post-assisted log structures (PALS) and beaver dam analogues (BDAs) are hand-built structures. PALS mimicand promote the processes of wood accumulation; whereas BDAs mimic and promote beaver dam activity. •PALS and BDAs are permeable, temporary structures, built using natural materials. •BDAs differ from PALS in and that BDAs create ponds using a variety of fill materials; PALS are built with only woody material, which tends to be larger diameter than the woody material used for BDAs.•PALS and BDAs are both intended to address the broad impairment of structural starvation in wadeable streams, but can also be used to mitigate against a range of more specific impairments. •PALS and BDAs can be built using a variety of natural materials, and built to a range of different shapes, sizes and orientations.•PALS and BDAs are most likely to achieve restoration goals when built in high numbers.•Some PALS and BDAs are likely to breach and/or lose some wood, but when many structures are installed, that material will accumulate on downstream structures or in natural accumulation areas leading to more complexity.
Chapter Two of Low-Tech Process-Based Restoration of Riverscapes: Design Manual (http://lowtechpbr.restoration.usu.edu)
Low-tech process-based restoration principles are critical to understand as both the basis for effectively applying low-tech restoration treatments and managing expectations about timing and magnitude of outcomes.
We propose and synthesize principles that help practitioners tackle low-tech process-based restoration of structurally-starved riverscapes. Many of these principles likely apply to a greater range of riverscapes, but we do not cover those applications here.
We break our guiding principles into:
- Riverscapes Principles - those that represent an understanding of what constitutes healthy riverscapes to help define what restoration should be aiming for; and
- Restoration Principles – those that influence the choices and approach we take in planning, designing and implementing low-tech restoration.
Since we focus on structurally-starved riverscapes, low-tech restoration that mimics and promotes the processes of wood accumulation and beaver dam activity specifically emerge out of these principles.
These principles collectively provide practitioners with the rationale and strategies to attempt to tackle the true scope of degradation with simple, smart, agile and scalable low-tech solutions that rely on the system itself to do most of the work of recovery and find self-sustaining and resilient futures.
This report, contracted by the Utah Division of Wildlife Resources (UDWR) describes an Adaptive Management Plan for the translocation of beaver as part of stream restoration efforts in the Grouse Creek Watershed (bid AS17157; purchase order no. 560 170000000000222) in northwest Box Elder County, UT. The purpose of this report is to present an adaptive management plan that guides the translocation of beaver into restored stream reaches along Pine Creek, Kimbell Creek, and Cotton Creek in order to achieve restoration objectives and also mitigate the potential threats that such translocation may produce. The report provides a simple framework to guide decision making and management action as it pertains to beaver translocation, monitoring beaver activity, and potential management actions in response to threats to infrastructure posed by beaver dam building activity. The plan identifies specific courses of action in response to different levels of risk and beaver activity, but also acknowledges that ultimately management decisions belong to the private land-owner, Jay Tanner, for whom the restoration was performed. There are limited infrastructure concerns within the proposed translocation reaches, as such much of this report is concerned with outlining a more generalized approach to identifying potential risks outside of the restoration and translocation areas and presenting a decision-making framework.
Riparian and aquatic habitats support biodiversity and key environmental processes in semi-arid and arid landscapes, but stressors such as conventional livestock grazing, wildfire, and drought can degrade their condition. To enhance habitat for fish and wildlife and increase resiliency in these critical areas, land managers in the interior western United States increasingly use alternative grazing strategies, beaver management, or beaver dam surrogates as low-effort, low-expense restoration approaches. In this study we used historical archives of satellite and aerial imagery spanning three decades to characterize riparian vegetation productivity and document beaver dam occurrences, then evaluated vegetation productivity relative to land management associated with livestock grazing and beaver dam densities while accounting for climate and wildfire. After controlling for stream characteristics such as stream size, elevation, and stream slope, we demonstrate a positive response of riparian area vegetation to conservation-oriented grazing approaches and livestock exclosures, extensive beaver dam development, increased precipitation, and lack of wildfire. We show that livestock management which emphasizes riparian recovery objectives can be an important precursor to beaver activity and describe 11 – 39% increases in floodplain vegetation productivity where conservation-oriented grazing approaches or livestock exclosures and high beaver activity occur together on low-gradient sites. Land management decisions can therefore potentially confer resiliency to riparian areas under changing and variable climate conditions – the increased vegetation productivity resulting from conservation-oriented grazing or exclosures and high amounts of beaver activity at our sites is the equivalent to moving conventionally-grazed, low-gradient sites without beaver up at least 250 m in elevation or increasing water year precipitation by at least 250 mm.
Beaver reintroductions and beaver dam structures are an increasingly utilized ecological tool for rehabilitating degraded streams, yet beaver dams can potentially impact upstream fish migrations. We collected two years of data on Arctic grayling movement through a series of beaver dams in a low gradient mountain stream, utilizing radio‐telemetry techniques, to determine how hydrology, dam characteristics, and fish attributes impeded passage and movement rates of spawning grayling. We compared fish movement between a “normal” flow year and a “low” flow year, determined grayling passage probabilities over dams in relation to a suite of factors, and predicted daily movement rates in relation to the number of dams each fish passed and distance between dams during upstream migration to spawning areas. We found that the average passage probability over unbreached beaver dams was 88%, though we found that it fell below 50% at specific dams. Upstream passage of grayling was affected by three main characteristics: (a) temperature, (b) breach status, and (c) hydrologic linkages that connect sections of stream above and below the dam. Other variables influence passage, but to a lesser degree. Cumulative passage varied with distance upstream and total number of dams passed in low versus normal flow years, while movement rates upstream slowed as fish swam closer to dams. Our findings demonstrate that upstream passage of fish over beaver dams is strongly correlated with hydrologic conditions with moderate controls by dam‐ and fish‐level characteristics. Our results provide a framework that can be applied to reduce barrier effects when and where beaver dams pose a significant threat to the upstream migration of fish populations while maintaining the diverse ecological benefits of beaver activity when dams are not a threat to fish passage.
Stream restoration approaches most often quantify habitat degradation, and therefore recovery objectives, on aquatic habitat metrics based on a narrow range of species needs (e.g., salmon and trout), as well as channel evolution models and channel design tools biased toward single‐threaded, and “sediment‐balanced” channel patterns. Although this strategy enhances perceived habitat needs, it often fails to properly identify the underlying geomorphological and ecological processes limiting species recovery and ecosystem restoration. In this paper, a unique process‐based approach to restoration that strives to restore degraded stream, river, or meadow systems to the premanipulated condition is presented. The proposed relatively simple Geomorphic Grade Line (GGL) design method is based on Geographic Information System (GIS) and field‐based analyses and the development of design maps using relative elevation models that expose the relic predisturbance valley surface. Several case studies are presented to both describe the development of the GGL method and to illustrate how the GGL method of evaluating valley surfaces has been applied to Stage 0 restoration design. The paper also summarizes the wide applicability of the GGL method, the advantages and limitations of the method, and key considerations for future designers of Stage 0 systems anywhere in the world. By presenting this ongoing Stage 0 restoration work, the authors hope to inspire other practitioners to embrace the restoration of dynamism and diversity through restoring the processes that create multifaceted river systems that provide long‐term resiliency, meta‐stability, larger and more complex and diverse habitats, and optimal ecosystem benefits.
This was a talk expanding the classic river health analogy to think about what role restoration actions can play in contributing to a rivers health. The talk attempts to make the case for low-tech process based restoration as feeding meals to promote specific exercise (processes), as part of a healthy lifestyle for rivers. By contrast, most restoration practice is overly focused on surgery as the only restoration tool.
Restoration of riparian and wet meadow ecosystems in semi‐arid rangelands of the western U.S. is a high priority given their ecological and hydrological importance in the region. However, traditional restoration approaches are often intensive and costly, limiting the extent over which they can be applied. Practitioners are increasingly trying new restoration techniques that are more cost effective, less intensive, and can more practically scale up to the scope of degradation. Unfortunately, practitioners typically lack resources to undertake outcome‐based evaluations necessary to judge the efficacy of these techniques. In this study, we use freely‐available, satellite remote sensing to explore changes in vegetation productivity (NDVI) of three distinct, low‐tech riparian and wet meadow restoration projects. Case studies are presented that range in geographic location (Colorado, Oregon, and Nevada), restoration practice (Zeedyk structures, beaver dam analogs, and grazing management), and time since implementation. Restoration practices resulted in increased vegetation productivity of up to 25% and increased annual persistence of productive vegetation. Improvements in productivity with time since restoration suggest that elevated resilience may further enhance wildlife habitat and increase forage production. Long‐term, documented outcomes of conservation are rare; we hope our findings empower practitioners to further monitor and explore the use of low‐tech methods for restoration of ecohydrologic processes at meaningful spatial scales.
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