"Riparian buffer" refers to the vegetated area of land adjacent to a pond, lake, stream, creek, river, or wetland. Riparian areas form the transition between the aquatic and terrestrial environment. Preserving and restoring riparian buffers are among the most effective techniques used to protect and enhance the quality of groundwater, surface water and wildlife habitats.
Riparian buffers include areas of trees, shrubs and other vegetation adjacent to a body of water, and help maintain the integrity of stream channels and reduce the impact of pollution by filtering out sediments, nutrients and other chemicals. Buffers also supply food, cover and thermal protection to fish and other wildlife. Riparian buffers also protect waterways from the impact of human activities such as farming, grazing, lumbering, mining and development. This vegetation intercepts polluted and sediment-laden stormwater running off the land surface before it reaches the water body. Buffers are most critical in watershed headwater areas and smaller first and second order streams. Buffers along the wider downstream portions of a watershed are important, especially for fisheries and wildlife habitat, but will have proportionately less impact on water quality.
Historically, forest and riparian buffers protected most of the streams and creeks in the County. Deforestation associated with agriculture, industry, and urban expansion over the past 300 years has drastically reduced the extent of streambanks protected by a buffer. This tool describes techniques local municipalities can use to create new buffers, as well as preserve and maintain existing buffers.
Riparian buffers along streams provide the following critical environmental functions:
- Energy Conservation: Riparian buffers reduce the thermal loading of streams, as well as the potential for erosion, pollution and flooding. This allows streams to carry out their natural functions, thus reducing energy demands associated with repairing the damage associated with these issues.
- Peak storm flow reduction: Stormwater runoff can be slowed and infiltrated in a forested riparian buffer, helping to reduce peak flow of water in a stream during a storm event. This action may help prevent or reduce flooding in downstream areas.
- Filtering pollutants: Pesticides and other pollutants contained in storm runoff are detained by tree leaf litter and upper layers of the soil where beneficial bacteria and exposure to the atmosphere help break them down into less harmful components.
- Nutrient uptake: When detained by leaf litter and the soil, plant nutrients that originate from activities on the land are taken up by tree roots. Nutrients, traveling in stormwater runoff as nitrate and phosphate, are used by the growing plants and stored in leaves, limbs, and roots instead of reaching the stream and mixing with the water where they can negatively affect aquatic organisms.
- Streambank stabilization: Trees in many streamside environments have deep and expansive root systems that hold the soil in place, helping to stabilize streambanks and reduce erosion. Severe streambank erosion can damage structures, roads and agricultural land.
- Shade: The leaf canopy of a tree-lined stream provides shade that keeps water cool. Cooler water retains more dissolved oxygen needed by fish, and encourages the growth of the diverse types of algae and aquatic insects that are part of a healthy food chain. Trout are known not to tolerate increases in water temperature associated with the absence of streamside trees.
- Food: Leaves that fall into a stream and are trapped on woody debris and rocks provide food and habitat for small bottom-dwelling creatures critical to the food chain.
- Flood damage mitigation: Well-established vegetation growing along a streambank reduces the velocity of flowing water, making it less damaging to structures.
- Habitats: Streams that travel through woodlands provide more habitats for fish and wildlife. Tree branches and limbs that fall across or into the stream serve as cover for fish and provide woody debris needed to support aquatic invertebrates. Buffers also provide habitat and travel corridors for terrestrial animals. Each mile of 50-foot buffer on both sides of a stream protects 12 acres of habitat.
- Air pollution mitigation: Riparian buffers trap and filter atmospheric pollution.
The following limitations are associated with the implementation of riparian buffers at the local municipal level:
- There is considerable discussion and literature on the exact width of buffer necessary to be effective and provide measurable benefits. Buffers up to 300 feet wide represent an ideal situation. However, voluntary restriction of active land uses within a buffer that wide may be difficult to obtain from some property owners and mandatory restrictions of that width may be subject to legal challenge.
- While there is scientific evidence to support local ordinances which prohibit the removal of trees and disturbance of other vegetation within 15 to 25 feet of a water body or wetland, prohibiting all land disturbance or tree and vegetation removal in a much wider buffer (such as the 300-foot width mentioned above) may be too restrictive. Local ordinances requiring riparian buffers need to be flexible to allow consideration for specific site characteristics.
- Municipalities may need to offer some type of incentive to developers for preserving buffers greater than 25 feet wide.
- The cooperation and assistance of government agencies, adjacent municipalities, and land trusts may be needed to establish corridors or networks of streams possessing continuous buffers.
How To Use This Tool
There are a variety of ways to preserve and protect riparian buffers during normal land use activities as well as during the land development process. Municipalities can manage stream corridors and their buffers through both non-regulatory and regulatory processes. Active planning and involvement by the local municipal government can be very effective in conserving this critical component of the natural environment.
Non-regulatory Techniques: Municipal comprehensive planning, including open space and recreation planning, is the most direct process for establishing municipal conservation efforts. These plans can contain maps, inventories and descriptions of the streams and riparian areas in a municipality, and goals and objectives for their conservation. Acquisition of riparian lands and/or conservation easements by the municipality can be an important part of implementing such plans. Municipalities can then work to restore and maintain buffers along their own riparian property. Both active and passive recreational activities can be integrated into riparian buffer areas. The Chester County Board of Commissioners is currently providing funding through the Heritage Park and Open Space Municipal Grant Program for greenway projects.
Municipalities may request "riparian easements" from the developer. This easement gives the township and its representatives access to the property to create and maintain buffer areas. Municipal governments can also cooperate with the Chester County Conservation District and local watershed protection groups to help inform riparian landowners about best management practices that protect buffers. Municipalities can also encourage landowners to sell or donate riparian conservation easements to a land trust, and provide funds and/or in-kind assistance for local stream restoration projects.
Other non-regulatory activities for conserving riparian buffers in which local municipalities can participate include:
- Support for municipal Agricultural Security Areas, farmland preservation, and the use of conservation plans. Farm owners interested in preserving their farms must belong to the Agricultural Security Area to be eligible for County or state agricultural land preservation programs.
- Application for funding for new municipal parks containing riparian areas through the Chester County Park and Open Space Municipal Grant Program and other state grant programs.
- Apply for funding for municipal comprehensive plan and ordinance updates through the Chester County Vision Partnership Program.
- Support local watershed organizations in their efforts to complete Rivers Conservation Plans.
Regulatory Techniques: Municipalities can provide for the health, safety and welfare of their communities by regulating land use activities to preserve and protect riparian buffers and other critical resources. For example, some municipalities in Chester County regulate the intensity and amount of logging or tree removal that can occur on private property, particularly along riparian areas. Property owners can be required to submit conservation or silviculture plans to the municipality for approval before substantial land disturbance or tree removal operations commence.
Some riparian buffers are protected by existing regulations. For example, activities within floodplain areas adjacent to streams and other water bodies are strictly regulated by state and federal agencies. Wetlands are protected by state and federal law and sometimes by local ordinances. Some riparian buffers may be at least partially protected through existing local ordinances that restrict or prohibit land development on steep slopes or limit disturbance of woodlands.
Municipalities can employ a variety of regulatory techniques to preserve riparian buffers and other environmentally sensitive lands. The Riparian Corridor Conservation District is a very comprehensive approach that can be incorporated into a local zoning ordinance.
- Easttown Township has a riparian buffer provisions appropriate for a more developed community.
- North Coventry Township's regulations relate to grading, erosion and sediment control and storm water management.
- Pennsbury Township's Subdivision and Land Development Ordinance
Riparian Buffer Width, Vegetative Cover, and Nitrogen Removal Effectiveness: A Review of the Current Science and Regulations. EPA/600/R-05/118 October 2005 by Paul M. Mayer, Steven K. Reynolds, Jr., Timothy J. Canfield. U.S. Environmental Protection Agency Office of Research and Development, National Risk Management Research Laboratory