How Wide a Buffer is Needed? |
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Different widths are needed to accomplish
the various benefits of a buffer. |
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The wider a buffer, the more values and benefits are incorporated. The greatest widths are needed to accommodate terrestrial wildlife habitat for those species that are particularly dependent on aquatic ecosystems. Shorter widths are needed to provide bank stability and benefits to shallow water habitat. |
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Bank Stability |
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Bank stability can be provided by a buffer width as narrow as 15 feet when the slope is not steep. Bank vegetation should be a mixtures of trees, shrubs and groundcover. Greater widths are needed on shores that experience ice damage, high winds and waves, significant water level variations or are steep.
A naturally vegetated bank provides long-term stability that an artificial structure does not. Retaining walls are expensive, need to be periodically repaired or replaced, and provide no habitat benefits. While they may fix an erosion problem, thus benefitting water quality, re-establishing a vegetated bank would provide many more benefits to a lake. |
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On steeper slopes, greater widths are needed to provide overall slope stability. A steep wooded bank can still fail if the wooded growth does not extend up the slope and over the top of the slope to a flatter area. Therefore, on slopes steeper than 15%, the buffer should extent to the top of the slope and 30 feet beyond it.
Here an entire steep wooded slope (a buffer of 100 feet) slid into the lake because trees were cleared above the buffer on the steep slope.
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Shallow Water Habitat |
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The critical interaction between shore vegetation and the shallow water habitat benefits from natural vegetation that provides woody and leafy debris, and shade.
Woody and leaves debris provide basic habitat structure; surfaces for micro-organisms and aquatic insects to live on; and places for fish fry to feed and hide in.
Fallen trees, branches and leaf decompose very slowly in the water and provide habitat structure for many decades. While these are a source of nutrients to a lake, they can be considered "background" sources of benefit to the lake. |
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Trees up to the shore and overhanging branches keep shallow water cooler, which is better for many fish species. In addition, areas of floating- leaved plants such as these waterlilies also provide shade and shelter. |
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Any angler or snorkler knows that if you want to see fish, big and small, head for the aquatic plant beds or fallen trees. |
Water Quality Protection |
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Providing a buffer strip of natural vegetation (woods) between uphill development and the lake allows runoff to be filtered and absorbed. 100 feet is a width that research shows removes 80-90% of pollutants.
Buffer widths wider than 100 feet are needed on steeper slopes and denser soils. Runoff moves more quickly on steep slopes, so a longer distance is needed to ensure absorption.
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A buffer can be gently pruned to provide views of the lake while still allowing water treatment benefits.
This camp owner has removed some lower branches, but still maintained a canopy layer and a shrub layer. |
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In order for pollutants to be properly removed, runoff must enter the buffer as spread out "sheet flow," not channelized flow. Therefore development should be designed (or retrofitted) to spread runoff out and prevent concentrated water flow from reaching the lake.
Here a lakeshore camp owner has installed waterbars on a steep driveway to direct the flow into the woods where it can be absorbed. Rain barrels, water gardens and grassy swales can also slow and spread out runoff from developed areas.
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Terrestrial Wildlife |
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Many bird, mammal, reptile and amphibian species need to spend at least some part of their life cyle near water.
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For instance some bird species, such as cedar waxwings, nest near water so they can feed their young insects they catch over water.
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Some of the more secretive bird and animal species such as thrushes, woodland warblers and moose, like wide buffer widths of up to 600 feet in order to be comfortable making use of the shoreland.
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While it is not possible to provide 600 feet of buffer around lakes that are already developed, it is important for the overall ecological lake health for some amount of shoreland to remain in an undeveloped condition. Lake and town residents can undertake shoreland conservation projects to keep some percentage of a shore undeveloped. |
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Water Quality Division 
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