A Better Explanation of Riparian Buffers

A buffer helps the lake but does not diminish the owners enjoyment

The Lake Fairlee Association has long been extolling the virtues of riparian buffers. They improve water quality, they protect the shore from erosion, and they just look good. The State of Vermont has put together a new web page that explains the whys and hows pretty well.

Choosing not to mow near the lakeshore creates a modest buffer

Vermont’s Act 250 constrains construction and other activities near the lake. Here is a LINK to a document clarifying the expectations of that Act.

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The following is adapted from this excellent web page created by the Vermont Department of Environmental Conservation.

Lakeshore Vegetation and Buffers

Overview

Natural lakeshore vegetation is critical to the long-term health of a lake environment. A “buffer” of native vegetation along the water’s edge separates the uphill land uses from the lake thus providing numerous water quality, scenic, privacy and habitat benefits. On this page you’ll read about the elements of a buffer, their values, and what you can do to enhance or protect shoreland vegetation on your lake.

What is a Buffer?

A buffer is a width of vegetated land between the lake and adjacent land uses. To function as a “buffer,” the vegetation should be a natural mixture of trees, shrubs, herbaceous plants, and the “duff” layer. Think of it as the native Vermont woods. A buffer has many components (leaf canopy layers, decomposing material, etc.) that function together to protect the lake, and many values (wildlife and aquatic habitat, filtration of runoff, bank stability, scenery, etc.).

A buffer is a naturally vegetated width of land between the water’s edge of a lake, stream or wetland, and uphill land uses. It is composed of a mix of trees, shrubs, ground cover and undisturbed ground.

Multiple layers of vegetation make up a buffer.

  • tree canopy
  • understory trees
  • shrubs of different heights
  • low growing groundcover
  • “duff,” the decomposing organic matter on the forest floor

These layers treat runoff entering the buffer from uphill as well as allow for maximum absorption of rainfall and numerous shallow water and shoreland habitat values.

The different layers of leaves both hold rain (up to 1/2 inch of rain can be held on the tree leaves) and slow its descent. Rain falling gently will erode the ground less or not at all.

The ground vegetation slows the runoff on the ground, encourages it to be absorbed into the soil, and catches and holds sediments that may be in the runoff.

The groundcover functions to both hold the soil in place and to treat runoff from uphill. Groundcover is a critical component of a buffer.

The duff, or decomposing organic matter, is an essential component of a buffer. Its spongy and absorbent characteristics allow for absorption of runoff from uphill land uses.

The lack of a duff layer is the reason why lawns do not provide the runoff treatment of a buffer, as lawns tend to be hard packed and offer little absorption. A lawn, even under trees, also does not provide most of the habitat values and benefits of a buffer.

The natural uneven ground of woods provides numerous crevices and small basins for runoff to be absorbed and removed of its pollutants

Values and Benefits of Buffers

The shoreland is the critical interface between the lake and the terrestrial environment.

  • Aquatic life gains important habitat materials (fallen leaves, branches and trees), food (fallen insects), and shade from overhanging vegetation
  • Many birds and animals depend on proximity to water for breeding or feeding and use the wooded buffer
  • A well-vegetated buffer will filter pollutants such as sediments and phosphorus out of runoff from uphill land uses
  • A buffer of diverse tree, shrub and plant species provides long-term bank stability
  • A wooded shore adds beauty to a lake experience

A naturally vegetated buffer along lakes provide numerous benefits to people and the environment, from protection of the water quality and beauty that bring people to the lake, to the functioning of the lake as part of a healthy ecological landscape.

Mown grass has shallow roots and cannot withstand the erosive forces of waves and high water.

A naturally vegetated shore provides bank stability through a complex mix of root depths and patterns.

Removing shore trees and shrubs exposes the adjacent shallow water to more sun and to increased sediment and phosphorus runoff. The increased light, warmer water and additional nutrients result in increased algae and nuisance plant growth in the immediate nearshore area.

In addition, a lake without, or with little, buffering vegetation will experience an overall increase in phosphorus concentration, meaning more algae growth everywhere and less water clarity.

People generally agree that shoreland vegetation increases the beauty of a lake

Summer resident Canada goose populations can be a messy problem for lakeshore residents. A brushy shore will discourage them from getting out on your property; they only like to get out where they can see an easy way back into the lake.

Fallen trees and branches, known as “woody debris,” and leaf litter form important habitat structure for insects to live on, small fish to hide in and feed on, and larger carnivorous fish to patrol the edges of. A silty or muddy bottom offers little diversity to support the variety of organisms found in shallow water.

Rocky cobbly areas also provide hiding places and many surfaces for aquatic insects and other animals to feed and live on. If the spaces between the rocks get filled in with eroded soil from adjacent land uses, the habitat quality becomes degraded.

Trees hanging over the water shade the shallows keeping them cool, and insects that fall off the branches are good fish food.

Generally in the shallows adjacent to a wooded shore, aquatic plant growth is not as dense as those nearshore areas where clearing has brought in more light and nutrients. Plants are important shallow water habitat structure similar to woody debris.

The plant bed at left offers shelter and feeding spots to small fish.

Frogs, crayfish and many other smaller animals depend on being able to hide in vegetation or under rocks in shallow water.

Nymphs, the aquatic phase of flying insects such as dragonflies, mayflies, damselflies and craneflies, live in protected spaces among the woody and leafy debris in shallow water. They need to be able to crawl out onto emergent plants or shore vegetation to shed their exoskeleton and emerge as flying adults.

Dragonflies and other flying insect eaters consume thousands of mosquitoes!

A wooded shore provides terrestrial habitat for the myriad of bird and mammal species that live or feed near water. Many aquatic species spend some life stage in the duff layer of the shore, including the weevil known to feed on Eurasian watermilfoil.

How Wide a Buffer is Needed?

Different widths are needed to accomplish the various benefits of a buffer.

Narrower buffers provide bank stability and promote shallow water habitat, but wider widths are needed to realize water quality treatment and even wider buffers provide wildlife habitat.

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.

Bank Stability

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.

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.

Shallow Water Habitat

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.

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.

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

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.

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.

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.

Terrestrial Wildlife

Many bird, mammal, reptile and amphibian species need to spend at least some part of their life cyle near water.

For instance some bird species, such as cedar waxwings, nest near water so they can feed their young insects they catch over water.

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.

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.

Promoting Buffers

There are a variety of ways to promote buffers and their importance in Vermont.

Vermont does not have state-wide regulations guiding development on shorelands; buffer promotion and enhancement must be accomplished locally. There are several means available to Vermonters wishing to address buffers on a lake or in their town.

  • Educate people with already developed lakeshore on how the property can be retrofitted for the benefit of the lake.
  • Educate people before they develop an undeveloped piece of shoreland about living on the lake in a lake-friendly manner.
  • Work with your town Conservation Commission or Planning Commission to promote good town policies and regulations that protect shorelands and lakes.

Enhance the vegetation on your own lakeshore!

Whether you have lawn to the shore or canopy trees, your camp is 20 feet from the lake or 100, there are probably ways in which vegetation and lake protection can be enhanced.  Then talk to your neighbors about it. Social science research shows that people learn and are influenced most by their friends and neighbors.

Educate people with already developed lakeshores on how they can replant and retrofit their property for the benefit of the lake.

Spread the Word Among Your Fellow Lake Residents

Distribute copies of handouts available on the Lake Protection Series webpage.

  • Offer information on good shoreland development methods to new shoreland owners by working with your town clerk.
  • Offer local meetings and workshops to discuss the importance of natural shoreland vegetation.
  • Order native plants as a group for shoreland revegetation through your localNatural Resources Conservation District. Most districts offer a spring plant sale of native species.

Communicate with New Shoreland Owners

Develop a “welcome package” for new shoreland owners including handouts on good shoreland development methods that will reach them before they start the clearing and building process.

Get Involved in Your Town

Participate in your town’s local government processes.

  • Many lake associations in Vermont have helped their towns obtain Better Backroads grants to fix town or private road erosion problems in the lake’s watershed.
  • Encourage the adoption of town shoreland regulations that set buffer widths and erosion control standards. Contact the VT League of Cities and Towns for technical assistance and a model ordinance.

Work to Conserve Lakeshores

Assess the lakeshore for stretches of undeveloped shore that might have potential for a shoreland conservation project. Through such a project, land is purchased by an entity (such as a local land trust, a conservancy, or the State of Vermont) interested in keeping it undeveloped. Or, more commonly, the “development rights” are purchased or donated and the original owner retains ownership but with restrictions on how it can be developed if at all.

For help and advice, contact the Lakes and Ponds Program staff.

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