Instream Restoration to Improve the Ecohydrologic Function of a Subalpine Meadow: Pre‐implementation Modeling with HEC‐RAS

Vegetation in subalpine meadows in the Sierra Nevada Mountains is particularly vulnerable to lowering of groundwater levels because wet meadow vegetation is reliant upon shallow groundwater during the dry summer growing season. These ecosystems are especially vulnerable to channel incision as meadow aquifers are hydrologically connected to tributaries, and many have not yet recovered from previous anthropogenic influences. While instream restoration projects have become a common approach, lack of postrestoration monitoring and communication often result in a trial‐and‐error approach. In this study we demonstrate that preimplementation modeling of possible instream restoration solutions, chosen to raise stream stage and subsequently groundwater levels, is a useful tool for evaluating and comparing potential channel modifications. Modeling allows us to identify strategic locations and specific methods. Results show additional sediment depth and roughness on tributaries along with introduced woody debris (simulated by high roughness) on the Tuolumne River are the most effective means of raising stream stage. Results demonstrate that restoration efforts are most efficient in tributary streams. Managers and planners can more efficiently direct resources while minimizing the potential for negative impacts or failed restoration projects by modeling the possible effects of multiple restoration scenarios before implementation.     

ON THE MEASUREMENT OF ENVIRONMENTAL IMPACTS OF PUBLIC PROJECTS FROM A SOCIOLOGICAL PERSPECTIVE1

ABSTRACT: The major objectives are (1) to identify the problems involved in measuring the environmental impacts of public projects from selected perspectives, and (2) to elaborate a sociological approach used in an empirical investigation in that respect. The construct of environmental impact of a planned action is generally operationalized from different perspectives and with different methodological emphases in the various disciplines. Even the term environment does not elicit agreement among users as to its exact meaning. Although there has been a steady increase in the number of studies from a sociological perspective concerning environmental problems, there is lack of sociological counsel in writing environmental impact statements. Overall, we lack sociological methodology and operational procedures for that purpose. In an attempt to bring some empirical focus to this field, attitudinal measures employed to discover how residents of a river basin perceived negative and positive environmental impacts of a proposed watershed development project are reviewed. These come from a study of creation of the Cooper Reservoir and Dam in Texas. Data on 343 heads of households m the selected areas were collected through structured questionnaires with items on personal information, a vested interest scale, a knowledge of the project scale, and an environmental impact scale. Data show that perception of impacts by residents is influenced significantly by degree of their vested interests involved. Variables for inclusion in a sociological model of environmental impact are suggested.     

USING TECHNICAL ADAPTIVE MANAGEMENT TO IMPROVE DESIGN GUIDELINES FOR URBAN INSTREAM STRUCTURES1

ABSTRACT: Adaptive management is a heuristic approach to treating stream restoration projects as continuous, cyclic experiments, yielding results to be incorporated into future decisions. This comprehensive assessment views failures as surprises that are valuable lessons. Monitoring, evaluation of data, and communication of results are critical; the monitoring results trigger feedback mechanisms to invoke adaptation to the newly acquired information and communication of new hypotheses, treatments, or policies. The principles of adaptive management were applied to a monitoring study of three urban stream restoration sites in Maryland. Data were collected and evaluated for various restoration techniques, including vanes, cross vanes, step pools, root wads, imbricated riprap walls, and coir fiber rolls. Improvements to the existing Maryland design guidelines and policies were developed as the feedback mechanism. With the increasing application of adaptive management in stream restoration efforts, it is likely that repeated failures will be prevented and future restoration projects will be more successful in achieving their goals.     

Evaluating the Illinois Stream Valley Segment Model as an Effective Management Tool

Stream habitat assessments are conducted to evaluate biological potential, determine anthropogenic impacts, and guide restoration projects. Utilizing these procedures, managers must first select a representative stream reach, which is typically selected based on several criteria. To develop a consistent and unbiased procedure for choosing sampling locations, the Illinois Department of Natural Resources and the Illinois Natural History Survey have proposed a technique by which watersheds are divided into homogeneous stream segments called valley segments. Valley segments are determined by GIS parameters including surficial geology, predicted flow, slope, and drainage area. To date, no research has been conducted to determine if the stream habitat within a valley segment is homogeneous and if different valley segments have varying habitat variables. Two abutting valley segments were randomly selected within 13 streams in the Embarras River watershed, located in east-central Illinois. One hundred meter reaches were randomly selected within each valley segment, and a transect method was used to quantify habitat characteristics of the stream channel. Habitat variables for each stream were combined through a principal components analysis (PCA) to measure environmental variation between abutting valley segments. A multivariate analysis of variance (MANOVA) was performed on PCA axes 1–3. The majority of abutting valley segments were significantly different from each other indicating that habitat variability within each valley segment was less than variability between valley segments (5.37 ≤ F ≤ 245.13; P ≤ 0.002). This comparison supports the use of the valley segment model as an effective management tool for identifying representative sampling locations and extrapolating reach-specific information.     

LANDSCAPE‐SCALE ANALYSIS AND MANAGEMENT OF CUMULATIVE IMPACTS TO RIPARIAN ECOSYSTEMS: PAST,PRESENT, AND FUTURE1

ABSTRACT: Analyses of cumulative impacts to riparian systems is an important yet elusive goal. Previous analyses have focused on comparing the number of hectares impacted to the number of hectares restored, without addressing the loss of riparian function or the effect of the spatial distribution of impacts. This paper presents an analysis of the spatial distribution of development‐related impacts to riparian ecosystems, that were authorized under Section 404 of the Clean Water Act. Impacts on habitat structure, contiguity, and landscape context were evaluated using functional indices scaled to regional reference sites. Impact sites were mapped using GIS and analyzed for spatial associations. Positive spatial autocorrelation (i.e. clustering of impact sites) resulted from the piecemeal approach to impact assessment, which failed to prevent cumulative impacts. Numerous small projects in close proximity have resulted in adverse impacts to entire stream reaches or have fragmented the aquatic resources to a point where overall functional capacity is impaired. Additionally, the ecological functions of unaffected areas have been diminished due to their proximity to degraded areas. A proactive approach to managing cumulative impacts is currently being used in Orange County, California as part of a Corps of Engineers sponsored Special Area Management Plan (SAMP). The SAMP process is evaluating the ecological conditions and physical processes of the study watersheds and attempting to plan future development in a manner that will guard against cumulative impacts.     

An analytical platform for cumulative impact assessment based on multiple futures: the impact of petroleum drilling and forest harvesting on moose (Alces alces) and marten (Martes americana) habitats in northeastern British Columbia

The combined influence on the environment of all projects occurring in a single area is evaluated through cumulative impact assessments (CIA), which consider the consequences of multiple projects, each insignificant on its own, yet important when evaluated collectively. Traditionally, future human activities are included in CIA using an analytical platform, commonly based on complex models that supply precise predictions but with reduced accuracy. To compensate for the lack of accuracy in current CIA approaches, we propose a shift in the paradigm governing CIA. The paradigm shift involves a change in the focus of CIA investigations from the detailed analysis of one unlikely future to the identification of the patterns describing multiple potential future changes in the environment. To illustrate the approach, a set of 144 possible and equally likely futures were developed that aimed to identify the potential impacts of forest harvesting and petroleum drilling on the habitat suitability of moose and marten in northeast British Columbia, Canada. The evolution of two measures of habitat suitability (average habitat suitability index and surface of the stands with habitat suitability index >0.5) revealed that the human activities could induce cycles in the habitat dynamics of moose and marten. The planning period of 100 years was separated into three distinct periods following a sinusoidal pattern (i.e., increase - constant - decrease in the habitat suitability measures). The attributes that could induce significant changes in the assessment of environment are the choice of harvesting age and species.     

In search of effective scales for stream management: does agroecoregion,watershed, or their intersection best explain the variance in stream macroinvertebrate communities?

Our lack of understanding of relationships between stream biotic communities and surrounding landscape conditions makes it difficult to determine the spatial scale at which management practices are best assessed. We investigated these relationships in the Minnesota River Basin, which is divided into major watersheds and agroecoregions which are based on soil type, geologic parent material, landscape slope steepness, and climatic factors affecting crop productivity. We collected macroinvertebrate and stream habitat data from 68 tributaries among three major watersheds and two agroecoregions. We tested the effectiveness of the two landscape classification systems (i.e., watershed, agroecoregion) in explaining variance in habitat and macroinvertebrate metrics, and analyzed the relative influence on macroinvertebrates of local habitat versus regional characteristics. Macroinvertebrate community composition was most strongly influenced by local habitat; the variance in habitat conditions was best explained at the scale of intersection of major watershed and agroecoregion (i.e., stream habitat conditions were most homogeneous within the physical regions of intersection of these two landscape classification systems). Our results are consistent with findings of other authors that most variation in macroinvertebrate community data from large agricultural catchments is attributable to local physical conditions. Our results are the first to test the hypothesis and demonstrate that the scale of intersection best explains these variances. The results suggest that management practices adjusted for both watershed and ecoregion characteristics, with the goal of improving physical habitat characteristics of local streams, may lead to better basin-wide water quality conditions and stream biological integrity.     

ENERGY,ENVIRONMENTAL, AND ECONOMIC IMPLICATIONS OF SOME RECENT ALBERTA WATER RESOURCES PROJECTS1

ABSTRACT: Most of us are aware, or feel we are aware, of the impacts of major water resources projects on our lives. “Dam-lovers” note the life-saving flood-risk reduction and recreational benefits of a proposed reservoir, while “dam-haters” bemoan the future drowning out of the wildlife habitat of its river valley, and the recreational disbenefits to stream (as opposed to lake) fishermen. Water supply projects can often be given such a revered status, assuming the “obvious” tenet that water, air, food, and shelter are basic requirements of decent living, that the economic viability of the project may not even be assessed. Water resources planners are supposed to impartially weigh the environmental and economic benefits, and especially now, the energy implications of all proposed water projects, but many times the partial views of political or public advocates may be hard to ignore. The assumptions used in the planning of four recent water projects in the Province of Alberta will be presented and some revisions suggested which materially affect their Benefit/Cost ratios. In one project that is still in the public hearing stage, the economic analysis will be revealed, indicating that the original B/C ratio of about 1.6:1 might be more realistically placed at 0.6:1. In another project just completed, the apparent lack of an economic or energy analysis that has resulted in a perpetual and unnecessary energy load on the province, will be described.     

Impact of riverine wetlands construction and operation on stream channel stability: Conceptual framework for geomorphic assessment

Wetland conservation is a critical environmental management issue. An emerging approach to this issue involves the construction of wetland environments. Because our understanding of wetlands function is incomplete and such projects must be monitored closely because they may have unanticipated impacts on ecological, hydrological, and geomorphological systems. Assessment of project-related impacts on stream channel stability is an important component of riverine wetlands construction and operation because enhanced erosion or deposition associated with unstable rivers can lead to loss of property, reductions in channel capacity, and degradation of water quality, aquatic habitat, and riparian aesthetics. The water/sediment budget concept provides a scientific framework for evaluating the impact of riverine wetlands construction and operation on stream channel stability. This concept is based on the principle of conservation of mass, i.e., the total amount of water and sediment moving through a specific reach of river must be conserved. Long-term measurements of channel sediment storage and other water/sediment budget components provide the basis for distinguishing between project-related impacts and those resulting from other causes. Changes in channel sediment storage that occur as a result of changes in internal inputs of water or sediment signal a project-related impact, whereas those associated with changes in upstream or tributary inputs denote a change in environmental conditions elsewhere in the watershed. A geomorphic assessment program based on the water/sediment budget concept has been implemented at the site of the Des Plaines River Wetlands Demonstration Projection near Chicago, Illinois, USA. Channel sediment storage changed little during the initial construction phase, suggesting that thus far the project has not affected stream channel stability.     

Impacts to Water Quality and Fish Habitat Associated with Maintaining Natural Channels for Flood Control

A field investigation conducted on Boulder Creek in Boulder, Colorado evaluated impacts of flood control maintenance activities on flood conveyance, water quality, and fish habitat. Thirty-nine transects were monitored at one control site and two maintenance sites over a period of eight months. Each site was visited on more than 50 occasions in order to characterize pre- and post-maintenance conditions, and to monitor maintenance activities. Measurements along the transects included substrate composition, flow depth, velocity, and elevation. Reach-average values were assigned to variables such as in-stream vegetation, streambank stability, and woody vegetation before and after maintenance. Water temperature, dissolved oxygen, pH, specific conductance, and turbidity were sampled, and habitat suitability indices were developed pre- and post-maintenance for seven indicator fish species. Water quality impacts during maintenance consisted of high turbidity levels (> 400 NTU), which returned to background levels (0.1–15 NTU) overnight, as well as changes in mean temperature and pH. Alteration of physical channel characteristics as a result of maintenance had limited effects on habitat quality for four of seven fish species, but caused improvements in habitat quality for three fish species. The main implications of this study for floodplain management are that: (1) Flood control maintenance practices can be in direct conflict with water quality and fish habitat objectives, and should be carefully designed and implemented by an interdisciplinary team. (2) Physical habitat for some fish species can be improved as well as reduced by maintenance activities. Habitat suitability curves may be useful tools for evaluating limiting factors of the habitat and for identifying opportunities for habitat improvements as part of maintenance.     

EFFECTIVENESS OF TIMBER HARVEST PRACTICES FOR CONTROLLING SEDIMENT RELATED WATER QUALITY IMPACTS1

ABSTRACT: Timber harvest best management practices (BMPs) in Washington State were evaluated to determine their effectiveness at achieving water quality standards pertaining to sediment related effects. A weight‐of‐evidence approach was used to determine BMP effectiveness based on assessment of erosion with sediment delivery to streams, physical disturbance of stream channels, and aquatic habitat conditions during the first two years following harvest. Stream buffers were effective at preventing chronic sediment delivery to streams and physical disturbance of stream channels. Practices for ground‐based harvest and cable yarding in the vicinity of small streams without buffers were ineffective or only partially effective at preventing water quality impacts. The primary operational factors influencing BMP effectiveness were: the proximity of ground disturbing activities to streams; presence or absence of designated stream buffers; the use of special timber falling and yarding practices intended to minimize physical disturbance of stream channels; and timing of harvest to occur during snow cover or frozen ground conditions. Important site factors included the density of small streams at harvest sites and the steepness of inner stream valley slopes. Recommendations are given for practices that provide a high confidence of achieving water quality standards by preventing chronic sediment delivery and avoiding direct stream channel disturbance.     

Creating False Images: Stream Restoration in an Urban Setting

Stream restoration has become a multibillion dollar business with mixed results as to its efficacy. This case study utilizes pre‐ and post‐monitoring data from restoration projects on an urban stream to assess how well stream conditions, publicly stated project goals, and project implementation align. Our research confirms previous studies showing little communication among academic researchers and restoration practitioners as well as provides further evidence that restoration efforts tend to focus on small‐scale, specific sites without considering broader land use patterns. This study advances our understanding of restoration by documenting that although improving ecological conditions is a stated goal for restoration projects, the implemented measures are not always focused on those issues that are the most ecologically salient. What these projects have accomplished is to protect the built environment and promote positive public perception. We argue that these disconnects among publicized goals for restoration, the implemented features, and actual stream conditions may create a false image of what an ecologically stable stream looks like and therefore perpetuate a false sense of optimism about the feasibility of restoring urban streams.     

Biodiversity Offsets: Two New Zealand Case Studies and an Assessment Framework

Biodiversity offsets are increasingly being used for securing biodiversity conservation outcomes as part of sustainable economic development to compensate for the residual unavoidable impacts of projects. Two recent New Zealand examples of biodiversity offsets are reviewed—while both are positive for biodiversity conservation, the process by which they were developed and approved was based more on the precautionary principal than on any formal framework. Based on this review and the broader offset literature, an environmental framework for developing and approving biodiversity offsets, comprising six principles, is outlined: (1) biodiversity offsets should only be used as part of an hierarchy of actions that first seeks to avoid impacts and then minimizes the impacts that do occur; (2) a guarantee is provided that the offset proposed will occur; (3) biodiversity offsets are inappropriate for certain ecosystem (or habitat) types because of their rarity or the presence of threatened species within them; (4) offsets most often involve the creation of new habitat, but can include protection of existing habitat where there is currently no protection; (5) a clear currency is required that allows transparent quantification of values to be lost and gained in order to ensure ecological equivalency between cleared and offset areas; (6) offsets must take into account both the uncertainty involved in obtaining the desired outcome for the offset area and the time-lag that is involved in reaching that point.     

Empowering communities – the role of intermediary organisations in community renewable energy projects in Indonesia

Community Renewable Energy (CRE) has been defying conventional energy systems for decades, though only recently it started to feature in academic and institutional discourses. Despite its new appeal, the literature on the impacts and factors influencing CRE projects is still scarce and builds mostly on studies in Europe and North America. In developing countries, where electricity access is low and energy poverty is prevalent, CRE can offer interesting opportunities for rural electrification and added benefits. The objective of this study is to assess the impacts of community-owned renewable energy projects and identify the internal and external drivers and barriers to their success. An exploratory case-study approach was used for collecting data, through interviews and observations, in two community micro-hydro projects in Indonesia. The results showed positive socio-economic impacts that exceed electrification benefits, and the reported success of community energy projects can be traced back to a combination of community-level as well as external factors. Yet, particularly important is the role of the intermediary organisation (Ibeka) in building communities’ ownership, enhancing (technical, entrepreneurial and managerial) capacities, transferring knowledge and technology, establishing innovative financing models and shaping policy. Such organisations are critical in bridging external and internal factors and thus represent a key element in integrating the proposed analytical frameworks.     

MORPHOLOGICAL FEATURES OF SMALL STREAMS: SIGNIFICANCE AND FUNCTION1

ABSTRACT: Throughout the United States, land managers are becoming increasingly aware of the importance of small streams for a wide range of resource benefits. Where channel morphology is modified or structural features are added, stream dynamics and energy dissipation need to be considered. Unit stream power, defined here as the time-rate loss of potential energy per unit mass of water, can be reduced by adding stream obstructions, increasing channel sinuosity, or increasing flow resistance with large roughness elements such as woody root systems, logs, boulders, or bedrock. Notable morphological features of small streams are pools, riffles, bed material, and channel banks. Pools, which vary in size, shape, and causative factors, are important rearing habitat for fish. Riffles represent storage locations for bed material and are generally utilized for spawning. The particle sizes and distributions of bed material influence channel characteristics, bedload transport, food supplies for fish, spawning conditions, cover, and rearing habitat. Riparian vegetation helps stabilize channel banks and contributes in various ways to fish productivity. Understanding each stream feature individually and in relation to all others is essential for proper stream management. Although engineered structures for modifying habitat may alter stream characteristics, channel morphology must ultimately be matched to the hydraulic, geologic, and (especially) vegetative constraints of a particular location.     

Improvements in Fluvial Stability Associated with Two‐Stage Ditch Construction in Mower County,Minnesota

Water quality and stream habitat in agricultural watersheds are under greater scrutiny as hydrologic pathways are altered to increase crop production. Agricultural drainage ditches function to remove water quickly from farmed landscapes. Conventional ditch designs lack the form and function of natural stream systems and tend to be unstable and provide inadequate habitat. In October of 2009, 1.89 km of a conventional drainage ditch in Mower County, Minnesota, was converted to an alternative system with a two‐stage channel to investigate the improvements in water quality, stability, and habitat. Longitudinal surveys show a 12‐fold increase in the pool‐riffle formation. Cross‐sectional surveys show an average increase in bankfull width of approximately 10% and may be associated to an increased frequency in large storm events. The average increase in bankfull depth was estimated as 18% but is largely influenced by pool formation. Rosgen Stability Analyses show the channel to be highly stable and the banks at a low risk of erosion. The average bankfull recurrence interval was estimated to be approximately 0.30 years. Overall, the two‐stage ditch design demonstrates an increase in fluvial stability, creating a more consistent sediment budget, and increasing the frequency of important instream habitat features, making this best management practice a viable option for addressing issues of erosion, sediment imbalance, and poor habitat in agricultural drainage systems.     

Stream Restoration Projects: A Critical Analysis of Urban Greening

Stream restoration projects are discussed in the context of their larger social purposes. Using a political ecology framework (including some of its European threads), the author explores how stream restoration initiatives have been carried out to date in the US and offers some preliminary reflections on how they could do more to advance environmental equity goals. Several aspects of how the endeavour is being carried out may inhibit progressive change, and they include: the metrics used to evaluate potential projects; the technical and managerialist construction of the problem definition; the understanding of what constitutes 'urban;' and the organizational aspects of stream restoration projects. While many stream restoration projects have made important contributions to their communities, a lack of comprehensive databases undermines full programme evaluation. The author concludes that both material and rhetorical dimensions of the stream restoration endeavour may be undermining the larger goals.     

Classification and spatial mapping of riparian habitat with applications toward management of streams impacted by nonpoint source pollution

Management of riparian habitats has been recognized for its importance in reducing instream effects of agricultural nonpoint source pollution. By serving as a buffer, well structured riparian habitats can reduce nonpoint source impacts by filtering surface runoff from field to stream. A system has been developed where key characteristics of riparian habitat, vegetation type, height, width, riparian and shoreline bank slope, and land use are classified as discrete categorical units. This classification system recognizes seven riparian vegetation types, which are determined by dominant plant type. Riparian and shoreline bank slope, in addition to riparian width and height, each consist of five categories. Classification by discrete units allows for ready digitizing of information for production of spatial maps using a geographic information system (GIS). The classification system was tested for field efficiency on Tom Beall Creek watershed, an agriculturally impacted third-order stream in the Clearwater River drainage, Nez Perce County, Idaho, USA. The classification system was simple to use during field applications and provided a good inventory of riparian habitat. After successful field tests, spatial maps were produced for each component using the Professional Map Analysis Package (pMAP), a GIS program. With pMAP, a map describing general riparian habitat condition was produced by combining the maps of components of riparian habitat, and the condition map was integrated with a map of soil erosion potential in order to determine areas along the stream that are susceptible to nonpoint source pollution inputs. Integration of spatial maps of riparian classification and watershed characteristics has great potential as a tool for aiding in making management decisions for mitigating off-site impacts of agricultural nonpoint source pollution.     

Ecological Responses to Trout Habitat Rehabilitation in a Northern Michigan Stream

Monitoring of stream restoration projects is often limited and success often focuses on a single taxon (e.g., salmonids), even though other aspects of stream structure and function may also respond to restoration activities. The Ottawa National Forest (ONF), Michigan, conducted a site-specific trout habitat improvement to enhance the trout fishery in Cook’s Run, a 3^rd-order stream that the ONF determined was negatively affected by past logging. Our objectives were to determine if the habitat improvement increased trout abundances and enhanced other ecological variables (overall habitat quality, organic matter retention, seston concentration, periphyton abundance, sediment organic matter content, and macroinvertebrate abundance and diversity) following rehabilitation. The addition of skybooms (underbank cover structures) and k-dams (pool-creating structures) increased the relative abundance of harvestable trout (>25 cm in total length) as intended but not overall trout abundances. Both rehabilitation techniques also increased maximum channel depth and organic matter retention, but only k-dams increased overall habitat quality. Neither approach significantly affected other ecological variables. The modest ecological response to this habitat improvement likely occurred because the system was not severely degraded beforehand, and thus small, local changes in habitat did not measurably affect most physical and ecological variables measured. However, increases in habitat volume and in organic matter retention may enhance stream biota in the long term.     

Rehabilitation and Flood Management Planning in a Steep,Boulder-Bedded Stream

This study demonstrates the integration of rehabilitation and flood management planning in a steep, boulder-bedded stream in a coastal urban catchment on the South Island of New Zealand. The Water of Leith, the primary stream flowing through the city of Dunedin, is used as a case study. The catchment is steep, with a short time of concentration and rapid hydrologic response, and the lower stream reaches are highly channelized with floodplain encroachment, a high potential for debris flows, significant flood risks, and severely degraded aquatic habitat. Because the objectives for rehabilitation and flood management in urban catchments are often conflicting, a number of types of analyses at both the catchment and the reach scales and careful planning with stakeholder consultation were needed for successful rehabilitation efforts. This included modeling and analysis of catchment hydrology, fluvial geomorphologic assessment, analysis of water quality and aquatic ecology, hydraulic modeling and flood risk evaluation, detailed feasibility studies, and preliminary design to optimize multiple rehabilitation and flood management objectives. The study showed that all of these analyses were needed for integrated rehabilitation and flood management and that some incremental improvements in stream ecological health, aesthetics, and public recreational opportunities could be achieved in this challenging environment. These methods should be considered in a range of types of stream rehabilitation projects.