|Session G Abstracts:
|The City of Austin - Stream Restoration Program
Morgan Byars, P.E., City of Austin Watershed Protection and Development Review Department, Stream Restoration Program, Austin, Texas
The City of Austin Stream Restoration Program works for the purpose of protecting property while enhancing the character of Austin’s waterways. Streams are dynamic living systems that are constantly adjusting to water, sediment, vegetation and the myriad of anthropogenic influences. For over a decade, the City of Austin Stream Restoration Program has been developing and implementing bioengineering and stream restoration practices that encourage stable systems, provide habitat and retain the natural and traditional character of streams in the urban environment. The SRP was established as the erosion control services program in 1994 in response to citizen complaints about creek erosion. Initially the focus was on implementing stream bank stabilization projects, but the program has evolved to include a more comprehensive multi-objective watershed approach to stream management. Program services include geomorphic assessments, regulatory initiatives, technical assistance, training seminars, planning, design and construction of stream restoration projects.
The City of Austin Watershed Protection Department (WPD) completed a city-wide watershed master plan in 2001. The master plan identified existing problems as well as outlined needs for problem prevention related to its three primary missions of flooding, erosion and storm water quality. The master plan initiated a multi-objective approach to assessing, prioritizing and solving watershed problems that includes identification of cross mission opportunities and impacts. The SRP utilizes this framework to develop solutions to stream stability problems that also consider the goals of flood hazard reduction and storm water quality treatment and protection. In addition the SRP attempts to include opportunities for public outreach and community education where possible.
The SRP achieves goals of reducing erosion hazards, restoring stream stability and preserving habitat through construction projects, voluntary buyouts, landscape restoration and regulatory programs. Examples of regulatory solutions include development of erosion hazard zone boundaries, on-site detention requirements and stable channel design criteria. Construction projects include stream stabilization using bioengineering and natural channel design approaches. Landscape restoration projects attempt to establish riparian zones with a complex of canopy, understory and ground cover. The latter may also include integration of LID stormwater systems and property acquisitions when appropriate. The SRP may implement these as capital improvements projects (CIP) using private consultants and contractors or with in-house engineers, scientists and City construction crews. The SRP utilizes 2 City construction crews year round to build and maintain stream restoration projects. Having access to multiple implementation resources allows the SRP to efficiently implement both large and small scale solutions. By considering multiple interests during the solution development process, the SRP can maximize opportunities for beneficial uses while minimizing adverse impacts to floodplains and those that interact with them.
|Assessing Surface Runoff As A Tool For Evaluating Watersheds And Stream Restoration
Pamela C. Dodds, Montrose, WV
The overhead trees on the Appalachian mountain ridges intercept rainfall so that it gently penetrates the ground as groundwater rather than flowing overland as runoff. This means that 1) the rain will gently fall to the ground and recharge groundwater and 2) the surface flow of rainwater on the ground will be slower than in cleared areas, thereby reducing the velocity and quantity of stormwater drainage. Conversely, where development occurs on forested ridges or where there are numerous roads constructed on forested ridges, the protective tree canopy is lost, the stormwater flow is greater in the cleared areas, groundwater is intercepted by road construction, and increased stormwater drainage results in habitat destruction within streams and the consequent death of aquatic organisms.
Surface runoff within a watershed can be evaluated using the equation Q = CIA, where Q is the discharge, C is the runoff coefficient for the ground cover, I is the rainfall intensity, and A is the area of the watershed. The surface runoff varies according to the ground cover, so the equation allows for “weighting” the areas according to the ground cover type and respective runoff coefficient. As documented in publications of the Center for Watershed Protection and of the American Society of Civil Engineers, the value of 10 percent impervious cover in a watershed has been determined to cause negative impacts. By calculating the surface runoff discharge where 10 percent impervious cover is present, this discharge value can be used as a threshold amount for evaluating the amount of deforestation or other development that will negatively impact the watershed. The surface runoff discharge resulting from 10 percent impervious cover can therefore be used as a tool to determine how much surface runoff discharge will cause negative impacts to a watershed and also how much of the watershed must be vegetated, especially in riparian buffer zones, to allow proper stream restoration activities to be successful.
|Retrofitting Urban Stormwater Infrastructure for Treatment and Ecological Enhancement in Philadelphia, PA
Rick Howley and Lance Butler, PWD-Office of Watersheds, Philadelphia, PA 19107
In 2005 the EPA established a sediment and nutrient TMDL for the Wissahickon Creek located in northwest Philadelphia. Wissahickon Creek is highly influenced by the urban infrastructure and landuses surrounding the stream corridor. In the early 20th century, the detrimental effects of stormwater and the need for management of it were not fully understood. During that time, tributaries to Wissahickon Creek were buried in separate sewer pipes and much of the neighborhoods, streets, and infrastructure in the Wissahickon Creek Watershed were built. Of the 11 square miles of the Wissahickon Creek watershed located in Philadelphia, 27% is impervious. Rainfall and the resulting run-off from these impervious areas has had a detrimental impact on the Wissahickon Creek and its tributaries. Sediment, nutrients, and other contamination from the city streets pollute the stream and flashy flows have severe impacts to stream corridor.
The City of Philadelphia Water Department (PWD) has taken a progressive approach to addressing stormwater run-off issues in the City’s watersheds. PWD’s analysis of the existing drainage system and the topography in the Wissahickon Creek has become the foundation for the creation of three large stormwater treatment wetlands. These wetlands are Saylor’s Grove, Wise’s Mill Run, and Cathedral Run Stormwater Treament Wetlands.
• Saylor’s Grove Wetland is a 1-acre stormwater wetland located in the Monoshone Creek subshed of Wissahickon Creek. Completed in 2006, the wetland manages stormwater from a 156-acre watershed.
• Wise’s Mill Run is another tributary to Wissahickon Creek. The wetland is located on a tributary to Wise’s Mill Run. Stormwater is routed from the stormwater conduit along Wise’s Mill Road and treated in a 1.9-acre wetland/bioretention facility, managing stormwater from a 100-acre watershed. Wise’s Mill is a comprehensive project also consisting of approximately 2000-feet of stream restoration coinciding with the wetland creation portion of the project. This project was completed in 2011.
• The Cathedral Run project is similar to Wise’s Mill Run and has wetland creation and stream restoration aspects. The Cathedral Run facility is 1-acre biorention wetland designed to manage stormwater from a 91-acre watershed. This project was completed in 2011.
After the construction of these facilities, PWD has taken several measures to maintain and monitor the wetlands. The reduction in sediment, nutrients, other urban contaminants, and peak flows prove that the stormwater treatment wetlands are very effective in accomplishing the goals established by the TMDL for pollutant removal and environmental restoration of the city. These wetlands will not only provide a valuable service to the community in their treatment of stormwater, but also in ecological improvement and park enhancement for the citizens of Philadelphia.
|Assessing Watershed Scale Responses to BMP Implementation in Urban Watersheds
John Jastram, USGS Virginia Water Science Center, Richmond, VA
The USGS Virginia Water Science Center, in cooperation with the Fairfax County Stormwater Planning Division, is conducting a study of urban/suburban watersheds in Fairfax County, Virginia to assess watershed-scale water-quality responses to implementation of Best Management Practices (BMPs) and stream restoration activities. Specifically, the objectives of the study are to: 1.) Describe current conditions and trends in both water quality and water quantity, compute loads in water-quality constituents, and use these data to evaluate water-quality improvements that are associated with BMP implementation and stream restoration activities, and 2.) Evaluate the transferability of results from intensively monitored watersheds to other watersheds with less-intensive monitoring. This unique study is reliant upon a long-term data collection effort in 14 small (1-6 mi2) watersheds that represent the range of land-use conditions in suburban Fairfax County. The study was designed to include a mix of intensively monitored watersheds, for which continuous streamflow and water-quality parameters are measured and over 100 routine and storm event samples are collected and less intensively monitored watersheds, for which periodic streamflow and water-quality measurements are made.
This presentation will include critical elements of the study design, the novel monitoring methods employed, and a discussion of preliminary results.
|Cumulative-Effects assessment and implementation of multi-stressor mitigation approaches in an intensively mined central Appalachian watershed.
Eric R Merriam and Todd Petty, West Virginia University, Morgantown, WV
Mountaintop removal-valley fill (MTR-VF) mining within the central Appalachians interacts with other natural (e.g. geography and geology) and anthropogenic (residential land use) factors to determine in-stream conditions across large spatial scales and over long periods of time. Current management strategies (permitting, mitigation, and restoration) often prove ineffective because they do not account for cumulative effects of multiple factors at the watershed scale. Through a watershed-scale analysis of the Coal River (south-central WV), we constructed predictive models linking landscape indicators to current in-stream conditions and projected cumulative effects of multiple stressors at the watershed scale. Boosted regression tree (BRT) models explained approximately 90% of the deviance in water chemistry (e.g., specific conductance and selenium) and physical habitat (i.e. habitat quality and complexity). Models of biological condition produced similar results, explaining 70-80% of the deviance in biological community metrics, such as EPT and WVSCI. By integrating these models within a spatially explicit modeling framework, we were able to project changes (degradation and improvement) in watershed conditions across a range of alternative mine development / restoration action scenarios. Sensitivity analyses indicate that restoration efforts targeted at reducing the effects of deep mine effluent and impacts from residential land use (e.g., habitat degradation and untreated wastewater) will result in the greatest ecological benefits at the watershed scale. Through these analyses we also identified thresholds of surface mining below which ecological impacts can be managed through strategic mitigation and above which impacts are likely to be unmanageable. The framework outlined in this study is transferrable to other regions and provides a necessary next step in the science and practice of cumulative effects assessment and implementation of watershed scale mitigation approaches.
|Beyond Channel Protection Volume (CPv): Moving From Stormwater Management to Integrated Restoration.
Erik Michelsen, South River Federation, Edgewater, MD
As part of the 2000 Maryland Stormwater Manual overhaul, a number of design engineering standards were changed and added in order to improve upon previous methods of stormwater management. Among them was the modification of the so-called “channel protection volume (Cpv),” which required 24-hour detention of the post-developed, one-year, design storm in upland practices, such as stormwater ponds. The driving force behind the addition of Cpv to the requirements was the recognition that the hydrologic changes associated with development can have significant impacts on deepening and widening stream channels, and that, particularly in urban environments, stream degradation contributes the vast majority of sediment loading to downstream resources.
Earlier attempts at channel protection, such as controlling the 2-year storm, were found not to reduce channel erosion, but instead to exacerbate it in some instances by extending the time that storm flows had to perform work on streams. All of these efforts were founded on the notion that stable stream systems are comprised of defined “bankfull discharges” channels, that convey the most frequently occurring flows (e.g., up to a 2-year return frequency discharge) but that spill out into the floodplain beyond that.
What if that entire paradigm is incorrect in the mid-Atlantic, and our efforts to convey these “bankfull” storm flows within stream channels have only hastened the demise of our creeks and rivers, and have helped contribute to the loss of countless acres of vital riparian habitat?
Historically, mid-Atlantic stream valley systems were perennially flooded – the very notion of a “floodplain” is a post-legacy sediment artifact, and researchers have coined the term “valley flat” to more accurately characterize these abandoned terraces along channels – and were comprised of an undifferentiated series of wet meadows, interspersed with vegetated mounds and islands, with water slowly coursing throughout. These systems were – and where they still exist, are – hugely effective at trapping sediment and processing nutrients, as well as providing vital habitat for some of the most endangered plant and animal communities in the region.
We should be encouraging the reconnection of streams with the valley flats – with appropriate protections for existing infrastructure, of course – and working to place additional protections on them whenever possible.
Moving forward, with the appropriate regulatory paradigm in place, new development has the capacity not only to stem the tide of additional insults to our rivers and the Chesapeake Bay, but to be one of the primary drivers of restoring its health. Rather than forcing the management of large, arbitrary water volumes on development sites we can require developers to go down into these degraded systems and truly protect our stream channels – by reconnecting them to the valley flats – providing myriad nutrient and sediment reduction benefits, capping historical sediments in place, and restoring and regenerating our nontidal streams and wetlands across the landscape.
Aiming for water quality treatment using low impact and environmental site design practices in the upland, with safe conveyance along a treatment train into these restored stream valleys represents the most effective way to meet the water quality goals that new stormwater regulations are aiming to achieve. Looking at these systems holistically, rather than bi-furcating stormwater management from environmental restoration, is the most cost-effective and sustainable way we have to recover our resources.
|Stream Restoration: Linking Environmental Benefits to Economic Benefits and Valuing Environmental Benefits
Danielle Schwarzmann, University of Maryland, Baltimore County, Baltimore, MD
This research identifies the links between environmental benefits of stream restoration and its economic benefits and discusses one approach to value the environmental benefits of stream restoration. Although the literature on the environmental effects of stream restoration is growing, there are a limited number of research studies that have sought to value the benefits of stream restoration despite the millions of dollars being spent on restoration. Knowing how people value the environmental benefits of restoration can inform watershed management decisions and policy outcomes.
Although there are markets for the products and services of many ecosystems such as clean water for drinking and aquatic species for human food consumption, many of the inputs provided by ecosystems are not valued because markets do not exist for them. Therefore, a price cannot be determined for these goods unless alternative methods of valuation (hedonic pricing, travel cost, or state preference methods) are used.
Valuing environmental services is important for many reasons including justifying government intervention, helping to decide between two alternatives that seek to obtain the same goals, and helping policymakers make educated decisions about the trade-offs between the uses of the environment, land and economic development. The research presented will explain the importance and provide a framework for linking environmental benefits to economic values of stream restoration and present what literature does this and where opportunities exist to expand this research.
Preliminary results from a contingent choice survey administered in the Maryland area that seeks to value and identify the preferences people have for various stream restoration attributes will also be presented. The survey asks people directly about their willingness to pay for stream restoration attributes and other environmental attitudes. The respondents are residents of the Maryland area living in various proximities to streams being considered for restoration.
|Watershed Approach to Restoring Streams and Wetlands in the Urban Upper Sandy Creek Watershed
Joshua White, Michael Baker Engineering, Inc., Cary, NC
The Upper Sandy Creek watershed is located in Durham County, NC. The 2.3 square mile urban watershed drains a portion of Duke University’s (Duke) campus and adjacent Durham neighborhoods. The watershed’s ecosystem had been greatly stressed due to the high percentage of urbanization. Upper Sandy Creek’s water quality had been impaired over several decades due to the urban development which contributed high concentrations of sediment, nitrogen, phosphorus, and coliform bacteria. This dysfunctional ecosystem had altered the watershed drainage by disconnecting the streams from their floodplains. The development had led to increased storm flows, increased bank heights, incision, stream widening, and removal from its floodplain.
Lower in Upper Sandy Creek’s watershed, Duke created a 20 acre Stream and Wetland Assessment Management Park (SWAMP) to monitor and assess the water quality benefits of restoring multiple sections of stream channel and connecting them to former wetlands. There are five phases to the SWAMP watershed approach and four of the phases have been completed with the last one awaiting funding for the construction process. Duke’s results from the first three phases are showing an increase in the stream and wetland connection, rebound in groundwater wetland hydrology, increase in stormwater retention, and a reduction in nutrients, coliform bacteria, sediment, and streambank erosion.
This presentation will focus on the different approaches within the watershed that was done to restore the streams and wetlands within SWAMP and how they have worked. The Upper Sandy Creek Watershed is unique in that the project, through several phases, was able to restore approximately 10,000 linear feet degraded streams and several acres of wetlands within an urban watershed. Comparisons will be presented between design techniques, construction logistics, channel stability, public safety, and overall site performance.
|Session H Abstracts:
|Stream Restoration Design and Environmental Benefit
Joe Berg, Biohabitats, Inc., Biohabitats, Baltimore, MD
Stream restoration has been and continues to be criticized as a poor management tool where millions to billions of dollars are spent with little to no resource benefit. This conclusion has been attributed to a lack of quantitative project goals, design or implementation failures, and a lack of measured benefits. Generally, too much emphasis has been placed on structural stability at the expense of other important attributes. This is particularly apparent in post-implementation monitoring which has not focused on documenting broad-scale benefits, but instead has been largely limited to measurements of channel form. Even under this rain of criticism, however, stream restoration is being considered for its utility in meeting TMDL attenuation goals. Limited independent research has linked stream and riparian restoration elements to superior stream restoration value (e.g., hydrograph attenuation, water quality benefits). In this context, desirable restoration elements mirror those features present in material processing stream reaches, including relatively large surface area to volume, aggradational nature, relatively long residence time in pools, abundance of carbon-rich substrate, frequent access to vegetated riparian/floodplain area, etc. Generally, conveyance channel reach features, such as a relatively large volume to surface area, systems in balance with sediment supply, facilitated positive drainage, mineral substrate, relatively limited contact with vegetated riparian/floodplain area, etc. are associated with streams that provide less functional value. This presentation will focus on relevant research, how and when to incorporate appropriate stream restoration design elements, an emphasis on common design elements that limit stream restoration benefits, and recommended actions to address the common criticisms leveled at the field of stream restoration and its practitioners.
|Stream Channel Succession and Sediment Yield : Black Vermillion River, KS
Tim Keane and Christopher Sass, Kansas State University, Manhattan, KS
The Black Vermillion River drains approximately 410 square miles in northeastern Kansas. The northeast corner of Kansas is the only portion of the state known to have been glaciated and is referred to as the Glaciated Region or the Dissected Till Plains for physiographic regional description. The entire drainage basin of the Black Vermillion River lies within Ecoregion 47: Western Corn Belt Plains. Surface materials are dominated by alluvium and glacial drift/till with some loessal influence in the extreme eastern part of the basin. Originally covered by native, warm-season tallgrass prairie, the basin has been modified extensively for agricultural production with significant impacts to the river channel and riparian landscape. Major channelization has shortened the river by nearly16 miles from pre-settlement dimensions; this shortening combined with the construction of numerous flow-through structures/dams have produced dramatic impacts on discharge and sediment dynamics.
In 2007, nine monitored stream reaches were established within three main tributaries of the Black Vermillion River of northeast Kansas. Each reach (average 1600’ in length) was surveyed and assessed for channel stability (Rosgen, 1996, 2006). Subsequent surveys were conducted in 2008 and again in 2009 along with monitoring of streambank erosion, bed scour, sediment size or distribution shifts, and other stability indicators. Initial surveys allow for geomorphic characterization and prediction of future trends, while re-surveys allow quantification of stability, as well as direction and rate of change along a stream successional sequence. This work allows the correlation of stream ‘state’ and in-channel sediment contributions, as well as prediction of future erosion rates based upon progression of stream succession. Our approach combines extensive field data collection with an understanding of stream process and form to assess current and future function and stability of channels.
This presentation briefly recounts our predictions of channel succession on the Black Vermillion River and the coincident sediment yield associated with establishment of a stable channel form at current bed elevations. Our calculations are based on the assumption that a stable channel and floodplain at current bed elevation is the most acceptable design solution in this tillage agriculture dominated landscape. The use of natural channel design parameters allows for the prediction of stable channel form and sediment yields associated with channel succession. Our measured erosion rates and basin-specific bank erosion curves (Sass, 2011) allow prediction of the time frame for stream channel succession. Such understanding is critical in determining not only how but when to most effectively mitigate the myriad of instability consequences. Work reported here is part of a USDA-CSREES project aimed at measurement and modeling of sediment sources, transport and deposition within the agricultural watersheds of the Black Vermillion River of northeastern Kansas.
|Functional measures of biotic recovery in an acid mine impacted stream remediated by alkaline addition: a five year study
Kelly S. Johnson, Biological Sciences, Ohio University; Jen Bowman, Voinovich School of Leadership and Public Affairs; Ben McCament, Ohio Dept. of Natural Resources, Division of Mineral Resources Management; and Pete Thompson and Lori Gromen, Masters of Environmental Studies Program, Ohio University
We monitored biological recovery of macroinvertebrates in an acid mine impacted stream after seven years of mitigation by alkaline addition. Hewett Fork receives AMD discharge from a large abandoned mine complex and is badly impacted for over 10 river miles, after which the waterway discharges into Raccoon Creek. The primary AMD source is an opening to the complex that discharges approximately 1195 lbs of acidity per day. Effluent prior to 2003 had a pH of 3.98, acidity of 466 mg/L, iron of 117 mg/L and Al of 37 mg/L. In late 2003, an AquaFix waterwheel calcium carbonate doser was installed. Seven long term sites along the 11 mile downstream reach were established for monitoring post-remediation water quality and biological recovery. The macroinvertebrate community was sampled annually at seven to nine study sites (2006-2011) during the summer using a modified rapid bioassessment field protocol. Water chemistry was monitored quarterly. In 2008, 2010, and 2011 several measures of ecosystem function were also measured along the recovery gradient. These included leaf litter breakdown rates, microbial respiration rates of conditioned leaves, seston quality, and biomass of the dominant shredder in autumn (Pycnopsyche sp, Limnephilidae).
Both structural and functional measures showed a consistent trend of biotic recovery downstream of the doser. Continuous addition of alkalinity produced a ten mile longitudinal gradient of improved water quality, evidenced by increased alkalinity, reduced acidity, increased pH and lower dissolved metals (Al, Fe, Mn). Structural metrics of the benthic macroinvertebrate community, monitored annually from 2001-2010, showed a gradual increase in diversity and abundance with increasing distance downstream of the doser. However, the extent of recovery varied depending on the metric, with several (macroinvertebrate abundance and % EPT taxa) exhibiting a spatial lag such that although annual targets for water pH, acidity and alkalinity were met 6 river miles downstream of the doser, macroinvertebrate communities remained significantly impaired for another 3-4 miles. Functional measures of biological recovery also
lagged spatially behind what the water chemistry parameters predicted. The functional measures strongly suggested that water chemistry as more limiting to ecological recovery than impaired physical habitat (poor native substrate, mining-associated flocculate, metal hydroxide precipitates or sedimentation).
We hypothesize that the poor biological recovery is most likely due to episoidic exceedences of pH and dissolved Al, Fe and Mn in a 4 mile long ‘transition zone’ downstream of the doser. Two additional possibilities are that recovery is limited by high loads of metals in sediment or more broadly reduced energy and nutrient flow along the stream continuum. In this study, a combination of structural and functional measures of biological integrity improved our understanding of the mechanisms and spatial patterns of recovery downstream of the doser.
|Spring Branch, Baltimore County, Maryland: A Bright Spot in Urban Stream Restoration
Paul Kovalcik, Biohabitats, Inc., Baltimore, MD; Vince Sortman, Biohabitats Inc., Denver, CO; Karen Ogle, Robert R. Ryan, and Dennis Genito, Baltimore County Department of Environmental Protection and Sustainability, Towson, MD
This presentation highlights two restoration projects along Spring Branch in Baltimore County which provide evidence of improved water quality, ecological connectivity and other benefits. Spring Branch, which is a second-order tributary to Loch Raven Reservoir, is the primary drinking water source for 1.8 million people in the greater Baltimore region. The Spring Branch watershed drains 1.6 square miles of residential communities developed prior to the implementation of stormwater management regulations and best management practices. This urbanization resulted in stream impacts including flashy hydrology, excessive sediment loads, and damaged and leaking lateral sewer lines. During development, over 2200 feet of the stream was lined with concrete in order to improve conveyance. Despite these impacts, the stream is designated as a cold water trout stream and public water supply (Maryland Use IIIP designation).
Because the primary watershed management goal for Spring Branch is drinking water protection, Spring Branch was chosen as a priority for stream restoration. Two projects have been completed on Spring Branch to date. The first was completed in 1997 and the second in 2008. In total the projects rehabilitated the majority of the free-flowing portion of the main channel (over 10,000 linear feet) and approximately 300 feet of tributary. Both projects incorporated natural channel design techniques to meet project goals for improving the flow regime, reducing channel erosion, improving stream habitat and longitudinal connectivity, sediment processing, protecting infrastructure, and establishing a vegetated riparian buffer.
The restoration projects along Spring Branch have resulted in nutrient reduction and habitat improvements, but the biological response has been variable. Reductions in the export of phosphorus, nitrogen, and total suspended solids have been consistent since the completion of the restoration projects. Improvements in stream habitat have resulted from removing the concrete channel, and additional habitat improvements are anticipated as the riparian vegetation matures. Macroinvertebrates have not stabilized or shown significant improvement, but the fish community, which showed little response after the initial restoration, increased in biomass and diversity in 2009 after the last section of concrete channel was removed. Baltimore County is currently working on a supplemental action plan for the watershed that will incorporate community involvement and hydrologic source control to further improve the stream.
The results thus far indicate that while urban stream rehabilitation may not provide the ideal situation to restore natural stream and floodplain attributes; the practice can still result in improvements to sediment and nutrient processing, water quality, and both lateral and longitudinal connectivity along the channel.
|Creative Design: The Handmaiden of Restoring Hydrologic Connectivity and Ecological Function
Ellen McClure, Biohabitats, Inc Baltimore, MD
Rapid growth in the industry of stream restoration is precipitating healthy debate regarding the efficacy of current practices. The focus of stream restoration projects has evolved as human populations relearn that healthy, self-sustaining rivers provide critical ecological and social goods and services. We are getting better at recognizing the importance of approaching stream restoration projects with a focus on providing critical stream functions and maximizing the spatial extent of beneficial modification via improving floodplain connectivity. Yet this aspiration is often compromised by the need to minimize impacts to the stream corridor. Further, for all participants in the stream restoration industry, there is very real pressure stemming from real-world budgetary and schedule constraints to make design an efficient, replicable, and readily reviewable process. More than ever, as an industry, we all are seeking to make our designs accountable and more transparent to these challenging questions.
Here we present one project attempt to rise to these challenges, though by no means perfect or complete. Stream and wetland restoration efforts undertaken by the Maryland State Highway Administration at Nixon Farm in Howard County, MD sought to provide stream restoration along the Middle Patuxent River and a segment of incised tributary, as well as over 10 acres of wetland creation, enhancement, and preservation on reclaimed agricultural land. Iterative conceptual design efforts focused on possible ways to boost site hydrology by capturing surface runoff, raising the groundwater table, and integrating stream and wetland hydrology. The design involved some unusual and creative elements, including 1) rerouting a tributary into an agricultural field and undersized drainage ditch, 2) installation of small berms across the field to maximize and focus infiltration and form microhabitat diversity, 3) installation of bentonite plugs along the abandoned tributary to form vernal pools, and 4) combining “regenerative stormwater conveyance” with more traditional stream restoration techniques.
Construction was completed in fall/winter 2010, and monitoring is underway. It is anticipated that the project will have significant positive effects on the groundwater and wetland hydrology of the floodplain, and will result in expansion of wetland distribution as well as an extended wetland hydroperiod.
|Assessing the Hydrologic and Hydraulic Processes and Connectivity in Altered Riverine Systems
Ward Oberholtzer, Landstudies & Century Engineering, Lititz, PA
Riverine systems have been severely altered due to agriculture, urbanization and mill dams. Interactions among key components that include groundwater, base flow, storm flow, and root zone have been altered, and the ecological benefits expected from an undisturbed riverine system have been reduced. These ecological benefits include aquatic habitat (spawning and rearing areas), nutrient and sediment attenuation, flood storage, habitat for native flora and fauna, and biological diversity. Changes in hydrologic and hydraulic processes, in particular those associated with lateral and longitudinal connectivity, are primary causes of ecological degradation. Assessing the connections among the key components is important not only in determining optimal restoration methods, but also in providing insights to the expected longitudinal and lateral changes in the riverine system if restoration is not incorporated. Proper assessment of the key components can be used in watershed scale planning, habitat restoration and nutrient and sediment load reductions (TMDL requirements).
|Retrospective Evaluation of Aquatic Ecosystem Restoration Projects Completed By The US Army Corps Of Engineers
David J. Tazik, J. Craig Fischenich, Erynn Maynard, and Justin Gardner, US Army Engineer Research & Development Center, Environmental Laboratory, Vicksburg, MS
Despite substantial investments in aquatic ecosystem restoration nationally, there is little or no quantitative monitoring of ecological response, and little or no basis upon which to assess project and program success. Furthermore, few national databases have been developed for ecosystem restoration projects. While the US Army Corps of Engineers has made substantial investments in restoration projects over the past 20 years, monitoring and assessment efforts within the Corps largely reflect this pattern. Better data and information is needed to ensure that the Corps’ restoration investments maximize environmental benefits to the Nation. This presentation describes an effort to develop and evaluate a database of ecosystem restoration projects completed by the US Army Corps of Engineers. Specific objectives are to evaluate the benefits realized relative to intended objectives, and the performance of selected restoration techniques and practices applied in wetland, coastal/estuary and riverine/stream systems. We also identify lessons learned and noteworthy projects that can help improve the performance and outcomes of future restoration efforts.
Information is being compiled for over 235 restoration projects that represent an investment of more than $660M. Projects included in the evaluation range widely in size, geographic location, habitat and ecosystem type, restoration features, funding authorities and partnerships. The presentation will illustrate the scope and diversity of the Corps ecosystem restoration program and summarize information on projected versus realized benefits and performance of selected restoration features. Particular emphasis will be placed on stream restoration efforts.