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Stream Stability

INDEX

• Background
•      Assessment
•      Protection
•      Management
•      Restoration
•      Education
• Opportunities for Private Funding
•      Examples of Projects or Types of Projects
•      Project Example

BACKGROUND

Most Vermont towns were established and developed along rivers and waterways. Before roads and electricity, the benefits of a river as a source of transport and power far outweighed the risks of flooding or water quality damage for most settlements. Vermont’s waterways have seen great changes during the past two centuries. Many watersheds were cleared of forests, and rivers were straightened and channelized. Flooding, sedimentation, and erosion have become increasing problems.

Rivers carry sediment and phosphorus that is eroded from riverbanks to Lake Champlain. Natural riverbank erosion is a continual process and often occurs dramatically during large flood events. Human activities over the past two centuries have changed the depth and slope of rivers and altered the natural channel adjustment process. Every Vermont watershed has streams “in adjustment,” where bank erosion may contribute significant amounts of phosphorus loading. Stream channel instability occurs throughout Vermont watersheds in the Lake Champlain Basin.

A massive load of sediment was carried to Lake Champlain from this unstable riverbank. West Branch, Stowe

The stream adjustments that occur in response to disturbance are part of a predictable process that often results in conflicts with human investments along riparian corridors, such as transportation infrastructure, agricultural lands, and residential and commercial properties. As these conflicts build, traditional channel management activities often contribute to a cycle of ever-increasing conflict, channel instability and cost. Similarly, existing floodplain management mechanisms, while important, deal primarily with preventing inundation and do not adequately address other activities that may directly or indirectly lead to greater channel instability and an increased magnitude of sediment and phosphorus discharges.

A stable, balanced river is one that is just wide enough, deep enough, and long enough to move the amount of water and gravel produced in its watershed. A stable stream will erode its banks and change course only minimally, even in flood situations. However, if a river becomes unstable, then it will change course, slope, depth, and/or width until it becomes balanced again. An important way to keep rivers from becoming unbalanced, or to allow them to re-establish stability, is to protect their river corridors. River corridors consist of the river channel, the banks on either side, and the areas close to the river that carry flood water and accommodate the meander pattern of the river.

Channel avulsion on the Trout River, 1997

Unstable streambanks and stream channels represent a potentially enormous source of sediment and phosphorus load to Lake Champlain. For instance, in a segment of the Trout River, one of the Missisquoi River’s largest tributaries, it was estimated the two channel avulsions across agricultural fields during a single flood event in 1997 resulted in a discharge of 6.9 metric tons of total phosphorus to the stream. A 1999 streambank condition inventory on the Wild Branch in the Lamoille River watershed described approximately 80% of the total stream length as suffering from head cutting and/or undercutting, sloughing, or mass wasting of streambanks. A 1998 inventory of riverbank lands owned by the Vermont Agency of Natural Resources along the Lamoille River found that 37% of streambanks were actively eroding or slumping into the river. The report also noted that this condition appeared to be representative of all 170 miles of riverbank, both public and private, along the Lamoille’s 85 mile length.

The Clean and Clear Action Plan recognizes the need to reduce phosphorus loading from this type of erosion and directs significant funding to improve stream stability in the Lake Champlain Basin. The science of fluvial geomorphology provides the understanding and the analytical tools necessary to properly manage river corridors to reduce conflicts with river processes, channel erosion, and phosphorus delivery to Lake Champlain. A successful plan to reduce fluvial sources of phosphorus should embrace a river corridor management strategy involving elements of science-based assessment, protection, management, restoration, and education, as described below.

ASSESSMENT

The proper foundation of protection, management, and restoration of rivers is a geomorphic assessment of the physical condition, sensitivity, and the adjustment process of discreet stream reaches. Implementation of a comprehensive assessment program will involve the following:

• Fluvial assessment training and typical field notes

  Stream Geomorphic Assessments: We need to identify the physical condition, sensitivity, and adjustment process of each stream reach in the Lake Champlain Basin. This action will require funds for assessment services under contract and staffing of the Vermont DEC River Management Program for training and quality assurance.
• Fluvial Data Management System: We need to make river data accessible to resource and land use managers, developers and landowners. This action will require funds to complete data system development and application, and staffing in the Vermont DEC River Management Program for data maintenance and retrieval assistance.
• Fluvial Assistance Capacity: We need to build the technical capabilities of watershed groups, Regional Planning Commissions, Conservation Districts, and the consulting community to conduct stream geomorphic assessments. This action will require staffing in the Vermont DEC River Management Program to provide technical assistance.

PROTECTION

Protection of river corridors from the encroachments that would lead to channel adjustment is much more cost-effective as a phosphorus control measure than restoration of rivers that have become unstable. Implementation of an effective and comprehensive riparian corridor and watershed protection strategy will involve the following elements:

• Fluvial erosion hazard map

  Fluvial Erosion Hazard Mapping: We need to assist public and private entities in identifying the riparian corridor necessary to maintain a stable, functioning, fluvial system. The Vermont River Management Program has developed a mapping methodology critical to describing local fluvial hazards. The program will support development of Federal Emergency Management Agency (FEMA) recommended Pre-Disaster Mitigation plans by communities and regional agencies. This action requires funding to develop erosion hazard maps for each basin municipality and staffing in the Vermont River Management Program to provide technical assistance and quality assurance.
• Land Use Incentives: The program will work with state and federal agencies to develop the incentives necessary to encourage and support implementation of fluvial assessment and river corridor protection strategies. Such strategies, identified in regional and local Pre-Disaster Mitigation Plans, will define community and individual land use management or protection mechanisms to minimize conflicts between the physical imperatives of fluvial systems and human investments on the landscape. The Fluvial Erosion Hazard Maps will guide these mechanisms. This action requires substantial annual incentives through state and federal grant authorities for meaningful riparian corridor protection including easement acquisitions. This action also requires staffing within the Department of Housing and Community Affairs and the Vermont DEC River Management Program to assist communities and provide technical assistance to local development review boards and Regional Planning Commissions.

MANAGEMENT

Management of fluvial systems addresses the everyday conflicts between river dynamics and human investments in the landscape. These day-to-day conflicts arise from a cycle where instability and erosion caused by a flood are followed by spot-fix channel management activities that cause streams to unravel further and increase their susceptibility to greater erosion and damage to public and private investments during the next flood. An effective riparian corridor and watershed management strategy must involve these elements:

Technical Assistance to Agriculture and Flood Hazard Mitigation Projects: We need to increase support of projects that treat the cause of channel instability rather than the symptom of erosion through the full participation of Vermont DEC River Management Program staff in flood hazard mitigation projects. We will create a greater emphasis on riparian corridor management activities in government-funded agricultural programs to assure that riparian corridor treatment projects are consistent with stable fluvial geomorphic processes. We will use enhanced techniques to identify highly erodible flood plain soils, distinguish the most effective phosphorus reduction practices, and assure that channel and streambank management practices are compatible with the long-term maintenance of stream stability. This action requires staffing in the Vermont DEC River Management Program.

Forestry Accepted Management Practices (AMPs): We need to establish silvicultural management practices that distinguish between land that can support bare ground harvesting vs. land that should only be worked when frozen or snow-covered. This action requires staffing for forest management education and AMP compliance.

RESTORATION

Restoration of a river reach

The restoration of unstable riparian corridors to a natural, stable condition is an expensive component of a phosphorus reduction strategy. Nevertheless, tremendous phosphorus reduction opportunities exist in conjunction with projects designed to restore aquatic ecosystems or mitigate flood hazards. Implementation of an effective and comprehensive riparian corridor and watershed restoration strategy will involve the following elements:

• Restoration Design Capacity: We need to train in-state consultants and contractors to evaluate geomorphic stream restoration alternatives and to design and construct geomorphically stable stream restoration projects. This action requires staffing in the Vermont DEC River Management Program for training purposes.
• Restoration Demonstration Projects: We need to implement projects based on natural channel design techniques to redefine the public’s perception of its relationship with fluvial systems. This action requires substantial seed funding to implement 5-10 large natural channel restoration projects in high priority, high profile areas, and project coordinator staff in the Vermont DEC River Management Program.

EDUCATION

A multimedia watershed education program targeted at landowners, municipalities, consultants, watershed associations, public sector scientists and engineers and other parties interested in the basin planning process will effectively communicate the results of stream geomorphic assessments and build the constituency necessary for reducing fluvial sources of phosphorus.

• Geomorphic Assessment Training Course: We need to deliver a training course to a broad range of professional, student, and volunteer technicians in the field and computer assessment protocols. This action requires funding for course development and staffing in the DEC River Management Program.
• Educational Videos and Fact Sheet Publications: We need to develop educational materials to demonstrate the spatial and temporal adjustments of stream channels in relation to historic channel, floodplain and land use practices and to restore ecosystem functions. This action requires funding for production and technical assistance.
• Economic Analysis and Research Partnerships: We need to carry out research projects in partnership with academia and public agencies in the area of fluvial geomorphic processes to analyze different channel and floodplain management and land use alternatives including short and long-term costs associated with various erosion control, flood hazard mitigation and phosphorus reduction strategies. This action requires research funding and staffing for coordination and technical assistance.

OPPORTUNITIES FOR PRIVATE FUNDING

The above describes the overall stream stability program. The comprehensive river corridor management strategy outlined above will require funding from a variety of state, federal, and private sources. While government funding sources and implementation by state and federal agencies are logical and underway for many of the needed actions, there will also be important opportunities for private funding support to extend the scope of the stream stability efforts and to take advantage of critical project opportunities that arise. Following are some areas of the overall program that may be appropriate for private funding.

Riparian corridor protection and restoration are probably the program areas where private funding contributions can make the biggest difference. Acquisition of easements for riparian land parcels identified through the science-based assessment process as being critical to stream stability is a key part of the protection program. Such projects may take years to develop through negotiations between land-owners, land trust organizations, and government agencies. Having funds readily available to take advantage of such riparian land protection opportunities would help bring these efforts to successful conclusion.

Stream restoration projects are expensive and highly visible efforts that could also benefit from a private source of funding. Restoration of eroded or avulsed stream channels to a more stable condition using science-based natural channel design techniques would be an excellent way to demonstrate the concepts while eliminating a significant source of phosphorus to Lake Champlain.

EXAMPLES OF PROJECTS OR TYPES OF PROJECTS

• The Northwest Regional Planning Commission is sponsoring a stream restoration project on the Tyler Branch in the Missisquoi Basin. The total project cost is $110,000, of which the US Army Corps of Engineers will contribute $71,000 in funding or services and, in this case, the state will provide the remaining $39,000 to match the Corps funding. It is quite common for local organizations to have worthwhile projects that they have the capacity to sponsor but do not have the money match federal funding. The state does not have the capacity to provide match dollars for all these projects. These types of projects would benefit greatly from private funding to provide the local match, and the private money could leverage significant amounts of federal funding.
• The City of St Albans developed a watershed improvement project for the Upper Stevens Brook watershed, but the project was not selected for an EPA nation-wide competitive grant. The $547,000 project may be eligible for some state or federal funding from other sources. Private funding, in partnership with other funding sources, would be helpful.
• Under the same federal grant competition the Northwest Regional Planning Commission submitted a $662,000 for improvements to the Tyler Branch but was not successful in obtaining a federal grant. This is another “ready to go” project that could benefit from private funding.

PROJECT EXAMPLE

River Corridor Restoration Stabilization Techniques to Reduce Sediment & Phosphorus Production - Before, During and After