Two distinct, but closely related, river (and to some extent, lake) issues need to be considered in bicycle or any transportation path planning: water quality and aquatic habitat protection. Most of the threats or impacts to water quality come from the adjacent land and so it is land activities and land management techniques that are the considerations. The threats or impacts to aquatic habitat can come from either land uses or from instream alterations. The issues and considerations for both of these aspects of river and lake protection are described below.
The greatest impairment to water quality in Vermont comes from nonpoint sources (diffuse sources) of poilution with sediment being the largest single cause of water quality problems in rivers. The sediments and attached nutrients that end up m our state's rivers and lakes come from numerous human activities along the shore and in the watershed including construction, road maintenance and repair, agricultural activities and logging. Buffer strips, which are bands of native vegetation, are effective and inexpensive (especially when left in place versus being re-established) ways of reducing sediment and nutrient pollution. A good buffer strip with trees, shrubs and ground-cover plants as well as an uncompacted soil surface will slow runoff allowing sediments to settle out and reducing the erosive force of the water. Sediments will become incorporated into the soil structure and nutrients will be taken up by the plants or also become part of the soils.
CONSIDERATIONS: Bikes and pedestrian paths should be constructed so that the water quality of lakes and rivers are protected, maintained, and improved to the greatest extent possible. The level of existing disturbance to the lakeshore or river corridor, soils and slopes, and construction erosion are important considerations: ~ Stretches of undeveloped river corridor or lake shoreline should be avoided whenever possible in order to prevent fragmenting natural communities, providing corridors for the introduction of alien species (plant and animal), disturbing or destabilizing soils and banks and encouraging further development and disturbance. ~ Depending on the soils, slope of the land, size of the river or stream and vegetation community present, there should be a buffer strip of adequate width between any path and the river bank or lakeshore. In general, a buffer strip should be at least 50 to 100 feet (15 to 30 meters) for water quality protection. In areas with more erodible soils or steep slopes, the buffer strips should be wider.
The width of the path along rivers, streams or lakes should be as narrow as possible so as to minimize the area of the soil and vegetation disturbance and the resultant compacted, impervious area. Currently Vermont uses federally defined minimum widths for paths: generally 3 meters (10 feet) for 2 way bicycle traffic. However, under certain circumstances the path can be 2.4 meters (8 feet). The applicability of this latter width should be explored during design of a path. The minimum width of graded area adjacent to each side of the path is 0.6 meters (2 feet).
Any bicycle or other path construction plan should include a soil erosion and sediment control plan. Prior to any land disturbance for construction, any necessary erosion control measures should be in place. Frosion control measure need to be inspected and maintained throughout construction and removed only when the site is stabilized.
Well planned and maintained access points from the path to the river or lake should be established in already used/disturbed areas to avoid widespread trampling and vegetation disturbance.
Vegetated lake shorelines and streambanks provide habitat for fish and other aquatic life. Lands adjacent to lakes, rivers, and wetlands should be protected, maintained, and improved so that they may serve the following aquatic habitat functions:
REFUGE HABITAT--fish like all other animals must have places that provide protective cover. Tree and shrub growth at the edge of the water provide overhanging branches, stable undercut banks, and instream snags.
STABLE STREAM FLOWS--a wider band of soil and vegetation will act as a sponge moderating peak flows during high runoff periods. More severe flow fluctuations will occur without these natural "sponges" and create a stressful environment for fish and other aquatic life.
COLDER WATER--cold water fish, especially adult trout and salmon, thrive in shaded streams or in the depths of larger rivers. Other "cool" water species, including younger fish, need the shaded areas along lake and river shorelines. When the shoreline or streamside canopy is removed, water temperatures can increase 10-20 degrees and fish may succumb to the stress of low dissolved oxygen concentrations.
FOOD SUPPLY--vegetation is the base of all food chains. In small shaded streams where little sunlight reaches the water, aquatic ecosystems rely on insects adapted for capturing the food contained in leaves and twigs falling from streamside vegetation. Fish key in on the life cycle of these insects for their own feeding success. Insects falling into the water from shoreline vegetation are important food sources for both lake and river fisheries.
CLEAR WATER--turbid water filled with sand and silt, brought on by unstable, eroding shorelines and streambanks, can have several illeffects on fish. Sedimentation covers fish spawning gravel and eliminates insect habitat in lake and stream bottoms. Turbid water clogs fish gills and makes it difficult for fish to see their insect food.
MEANDERING STREAM CHANNELS-meandering flow creates a sequence of pools and riffles within the stream. If the channel is straightened and/or widened, stream habitat becomes more uniform. The loss of cutting power on the outside bends of a stream results in the loss of deep pools that are important refuge habitat for adult fish. Erosion of inside meanders is accelerated both upstream and downstream of the straightened reach, encouraging more channelization, and covering riffle habitat with sediments.
CONS1DERATIONS: Bikes and pedestrian paths should be constructed so that the physical nature of lakes and rivers are protected, maintained, an improved to the greatest extent possible. The level of existing disturbance to the lakeshore or river corridor is an important consideration:
In urban settings where the lake shoreland or river banks are straightened and armored with rock (riprapped) to protect buildings and roads, the recreation path may fit close to top of the bank. These projects may provide a great opportunity for improving lake shorelands and river corridors. By designing the project with the greatest possible buffer between the path and the water, and maintaining or improving the amount of vegetation in the buffer area, the aquatic habitat may be significantly improved.
In rural and forest settings where shorelands and river corridors are in a more natural state, the recreatior path should be designed with aquatic habitat and the physical processes of water in mind. Well planned access points may provide enjoyable views of the water, otherwise, paths should be routed away from lakes and rivers to protect shoreland soils and vegetation. The distances mentioned in the water quality section would also serve to protect the physical aspects of aquatic habitat.
The meandering nature of streams and rivers should be kept in mind. Stream crossings with new bridges should be avoided or kept to a minimum. A near stream alignment may lead to a series of projects in the future to save the path and bridge abutments with rock armoring to stop erosion. These projects may be very expensive and the end result is a recreation path following a channelized stream that provides little value as habitat for fish and other aquatic life.
Two distinct, but closely related, surface water issues need to be considered in path and trail planning: water quality and aquatic habitat protection. Good water quality and aquatic habitat assure a diversity of plant and animal life and make the resource more enjoyable for recreation purposes. The greatest impairment to water quality comes from nonpoint sources of pollution with sediment from erosion being one of the most significant causes. Aquatic habitat is lost when the stream course is changed, the streambanks are altered, or the shade of overhanging vegetation is removed. The primary considerations in planning and developing paths and trails that are along or cross waterways include:
avoidance of unfragmented, Indeveloped tracts of land and free flowing river segments;
maintenance of a sufficient vegetated buffer between the trail and the watercourse;
erosion control measures to keep sediments out of the stream during construction and stormwater control measures to minimize erosion after construction; and
path and trail alignments that avoid the need for bridges and other stream alterations where riprapping may be necessary.
Well planned access points to a stream will give the path and trail user the unexpected pleasure of seeing the watercourse while allowing the stream to flow freely.
Answer the following questions and use the recommendation to plan a trail or bicycle path that will protect and enhance water quality and aquatic habitat. Notes are provided at the end to further explain the recommendations and indicate the organizations and agencies that may provide assistance.
1. Is the path planned for an urban area, rural area, or forest land?
IF URBAN, go to questions under # 2.
IF RURAL, go to questions under # 3.
IF UNFRACMENfED FOREST, go to questions under # 4.
2. Urban areas: developed shore land; existing transportation cor ridor; rip-rapped, stabilized, or modified channel.
a. Is there an existing road or trans portation corridor that can be used/modified for the path corridor)
IF YES, use the existing corridor (see Note 1).
IF NO, consider the other questions.
b. Are there rip-rapped banks that already prevent the live channel from moving?
IF YES, this provides an opportunity for a path to be closer to the river for viewing (see Note 2).
IF NO, keep the path set back from the river to prevent loss of the path due to the river meandering or the need to rip-rep or otherwise stabilize the bank (which means high path maintenance costs and harm to the river ecosystem).
c. Are there existing bridges or alignments that will eliminate the need for new river crossings?
IF YES, use the existing river crossings or design the path such that it crosses where there is an existing structure (see Note 3).
IF NO, re-design should be considered. Try to find a location where there are old bridge abutments or rip-rap.
d. is there existing natural vegetation along the desired corridor?
IF YES, design the path to leave all or most of the natural vegetation that exists along the river or stream.
IF NO, leave a strip of land, as wide as possible, to plant native vegetation that will stabilize the banks, protect water quality and enhance aquatic and wildlife habitat.
3. Rural Areas: suburban, low density residential--areas where human settlements and land uses are interspersed with natural areas.
a. Are there existing roads, railroad beds or other developed conidors that can be used or modified for the path corridor?
IF YES, use these corridors to the extent possible (see Note 1).
IF NO, consider the other questions.
b. Are there naturally or artificially stable sections of river channel, places where the river channel is not moving laterally because of bedrock or structures like rip-rap?
IF YES, these areas are more suited to closer alignment of a path and the river (see Note 4).
IF NO, the river is flowing freely and may support natural aquatic habitat. The path should be set back sufficiently so that the river has the space to meander as it needs. Allowing the river room to move will prevent costly repairs to the path in the future and protect the integrity of the aquatic ecosystem.
c. Are there wetlands present?
IF YES, development or alteration must stay at least 50 feet away from significant wetland communities (see Note 5).
IF NO, consider the other questions.
d. Are there highly erodible soils present?
IF YES, leave a large buffer strip of natural vegetation and supplement by planting with native species if needed (see Note 6).
IF NO, consider the other questions.
e. Is there a band of natural vegetation (trees, shrubs, and/or herbaceous plants) along the river, stream, or lake which the pedestrian path may disturb?
IF YES, design the path route such that a sufficiently wide (see Note 6) band of vegetation remains to protect water quality, bank stability, aquatic habitat and existing plant and animal communities.
IF NO, consider leaving a strip of land between the path and water in which a buffer strip can be established to protect both water quality (see Note 6) and the path (which may be threatened or washed out if the banks were eroded).
4. Wildland: unfragmented forestland.
a. Are there existing roads, railroad beds or other developed conidors that can be used or modified for the path corridor?
IF YES, use these corridors to the extent possible.
IF NO, consider only unpaved foot paths or avoid alignments that will enter these areas.
Notes
1. For example, if an existing road is in the desired location, contact the local and state agencies responsible for maintenance of the road and ask whether the road could be enhanced/widened to include a pedestrian lane. There may be mainte nance or upgrades scheduled for the road that could include the development of the path,
2. Materials placed on streambanks, such as large rocks, log-cribbing, or concrete retaining walls, are designed to stop erosion or lateral movements of the stream channel. In urban areas, these channel retaining structures are common due to the close proximity of developments along the stream or river. Placing bike paths along urban streams that have already been channelized may be an opportunity to improve aquatic habitat because further channel alteration would not be necessary and the project could include vegeta tion plantings between the path and stream.
3. If an existing bridge is near the desired location. contact the local and state agencies responsible for maintenance of the bridge and ask whether the bridge could be enhanced/widened to include a pedestrian lane. There may be maintenance or upgrades scheduled for the bridge that could include the development of the path.
4. Materials placed on streambanks. such as large rocks, log-cribbing, or retaining walls, are designed to stop erosion and lateral movements of the stream channel. In rural areas, these chan nel retaining structures may exist in or near village centers, along agricultural lands, or at current or historical bridge crossings. Bedrock that is at or near the surface of the land also stabilized river meandering. It may be possible to place bike paths near rural rivers without causing a loss of natural aquatic habitat, if it can be determined that the river is not likely to meander under most flood conditions. Stream alteration engineers with the Department of Environmental Conservation and the District Conservationists with the Soil Conservation Service will be aware of many of the channelized river segments in your area.
5. Contact the Wetlands office of the Department of Environmental Conservation to learn more about the identification of protection and the rules established for their protection.
6. Protecting and maintaining water quality and aquatic habitat depend on efforts to minimize erosion caused by land use activities. The tenden cy of soils to erode into surface waters is related to the slope of the land and the coarseness and organic content (erodibility) of the soils. In terms of erosion, the slope of the land is characterized in the following manner: 0-7% slight. 8-15% moderate, >15% high. Soil types in Vermont are assrgned erodibility coefficients and these soil factors are grouped as follows:.23 and lower, low soil erodibility;.24 to .36, moder ate soil erodibility; and .37 and higher, highly erodible soils. A formula can be used to calculate the width of a buffer, if you know the soil type and slope of the land. This formula and the associated tables are presumably available from the Water Quality Division at the address noted at the end of this fact sheet.
A table uses the formula to provide a quick reference for determining buffer widths. In general. where there are slight to moderate slopes and soils that are only slightly to modeiately erodible. buffer widths are needed to protect and maintain water quality and aquatic habitat. When slopes are moderate to high and soils are moderately to highly erodible, then buffer widths of 100 to 400 feet are needed. These tables and the associated formula are presumably available from the Water Quality Division at the address noted at the end of this fact sheet.
A Classification of Natural Rivers. 1994. David L. Rosgen. Catena. Vol.ZZ. No. 3-lune 1994. pgs 169-199.
Best Management Practices for Erosion Control During Trail Maintenance and Construction. 1994. lohn Twitchell et al. State of New Hampshire Trails Bureau. Concord, NH.
Erosion Control: Vermont Handbook for Soil Erosion and Sediment Control on Conrtrudion Sites. Special Publication No. 3 1982. Vermont Geological Survey and Vermont Department of Environmental Conservation. Waterbury. VT.
Erosion. Land Use, and Stream Ecology: A Manual for Lake Champlain Basin Communities. 1992. Linda Henzel. Lake Champlain Committee, Buliington, VT.
How Creenways Work: A Handbook on Ecology. Second Edition. 1992. lonathan M. Labaree. National Park Service and Atlantic Center for the Environment. Ipswich. MA.
Landscape Restoration Handbook. 1993. Donald Harker. Sherri Evans. Marc Evens, Kay Harker. Lewis Publishers. Boca Raton. FL.
Native Vegetation for Lakeshores. Streamsides. and Wetland Buffers: What you need to know to reestablish or enhance buffer strips along water and wetlands in Vermont. 1994. Catharine Kashanski Vermont Department of Environmental Conserva tion. Waterbury. VT.
Soil Bioengineering for Upland Slope Protection and Erosion Reduction. Engineering Field Handbook, Chapter 19. 1992. US Department of Agriculture. Soil Conservation Service.
Vermont Streambank Conservation Manual. 1987. Department of Environmental Conservation. Waterbury. VT