Riparian Buffers

Clean Water and the Waterways of Springfield

Source: Conserving Riparian Corridors [pdf]

A riparian corridor consists of the land along the banks of a stream or watercourse. At one time, most of Pennsylvania was forested. For centuries, riparian forests, the wooded or vegetated lands along both sides of a stream, provided shade for streams, protected streambanks from excessive erosion, and promoted a beneficial ecosystem in and along streams. The plants, animals, and insects living in the riparian woodland evolved accordingly and were well adapted to this setting. The organisms developed interdependencies with the surrounding environment, and the entire ecosystem consisted of balanced relationships, making it a sustainable landscape.

As Pennsylvania developed, the wooded riparian corridors were removed, and the streamside environment drastically changed. Without riparian forests, streams erode downward and develop a narrow, steeply sloped bed. Since this reduces available habitat, the stream lacks diversity. The habitat that does exist tends to have warmer temperatures, increased sunlight, drastic changes in stream flow and stormwater runoff, and invasive species. The balance of the ecosystem, established over a long period of time, has been disturbed. The ability of the disturbed landscape to sustain a balanced ecosystem is doubtful unless an effort is made to preserve these critical areas. To fully reap the benefits of riparian corridors, it is essential to retain corridors in a vegetated state, preferably as forests. When streamside lands are not forested, management efforts should be undertaken to assist the growth of woody vegetation and the reestablishment of woodlands. As discussed in the following section, the benefits of vegetated riparian corridors relate to how the corridors function to protect air, land, water quality, and animal habitat. While these benefits have been grouped into several broad categories, many interrelationships exist.

Benefits of Riparian Corridors

• Natural Floodplains. Vegetated riparian corridors with undeveloped floodplains slow the concentration of runoff and flood flows, reducing the height and velocity of floodwaters downstream.
• Control of Erosion. Riparian corridors can significantly reduce erosion of streambanks and adjoining floodplain, helping to prevent sedimentation of the stream. They reduce the velocity of runoff, allowing much of the sediment and attached phosphorus (roughly 85 percent of available phosphorus is bound to sediment) to be filtered out before reaching the stream.
• Water Quality/Stream Health. Riparian corridors enhance water quality in several ways. The vegetated corridor operates as a filter to reduce the flow of sediment and phosphorus into streams. This is especially important to water quality, since phosphorus is typically the nutrient that limits the growth and activity of aquatic organisms in fresh water. Riparian corridors also reduce the amount of nitrogen entering the stream directly or via shallow groundwater flow. Nitrogen applied to farmland or lawns as fertilizer or found in animal waste is water soluble and transforms to nitrate in runoff. Since nitrate does not attach to soil particles (as phosphorus does), it can leach into groundwater and streams. A riparian corridor will impede and intercept runoff from rain events and shallow groundwater flow. Once the runoff or shallow groundwater flow enters the riparian corridor, the nitrates are transformed by bacteria in the soil for consumption by the corridor’s vegetation.
• Habitat Protection. The disappearance of habitat for a variety of species is one of the problems caused by suburban development. In general, riparian corridors and greenways offer wide swaths of natural landscape, allowing various animals to move more safely among developed portions of a municipality and between larger open space habitats (i.e., parks and land preserves).
• Climate Moderation. The trees within forested riparian corridors add moisture to the air and create shade, significantly reducing air temperatures in the summer.

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The science says that a minimum 25-foot buffer is desirable to filter water before entering our streams. This buffer slows the water and cleanses the water. The county recommended a Riparian Ordinance for all Montgomery County towns and boroughs. In areas upcounty from us that are undeveloped, the 25-foot buffer makes a great deal of sense. However, for Springfield, which is so build-out, it didn't make good sense.

Is clean water important? Of course! Is the Riparian Ordinance the best solution to the problem? The Board of Commissioners wrestled with this question for years, sending the ordinance back to the Planning Commission several times. Finally the Board decided to table the concept and to educate our residents, through our EAC (Environmental Advisory Commission) and to proceed with three demonstration projects on township parklands, including a major one in Cisco Park (funded by Merck settlement money, see below).

The EAC will be preparing informational brochures for general distribution with recommendations for those who live along a stream and want to stabilize the streambank and contribute to improved water quality and stormwater management.

The Planning Commission is working on changing our code to permit riparian buffers, as they are currently in violation of § 11-1 "Accumulation of objectionable vegetation prohibited" in our code. [Ref]

The Board of Commissioners will be following the results of the demonstration projects closely and may, in future, reconsider a Riparian Ordinance for Springfield that is effective, responsible, and fair.

Cisco Park Project

The scope includes the stabilization of the Paper Mill Run stream embankment from the stone bridge (near Phil-Mont, part of the walking trail) to Paper Mill Road, and to add a riparian buffer along the length of the stream within Cisco Park. The goal is to reduce erosion (via the bank stabilization) and improve water quality (via the riparian buffer). We have until March 10, 2012 to complete the project, but hope to do so prior to this date.

Riparian Buffers and Flood Control

Source: Understanding the Science Behind Riparian Forest Buffers: Benefits to Communities and Landowners

Riparian forest buffers play an important role in flood control, as they provide a natural basin where floodwaters may spread out horizontally (Lowrance and others 1985). As flood waters move into the riparian area, vegetation slows the water's movement, reducing its erosive potential and capturing materials carried by the floodwaters (Gregory and others 1991). The porous forest floor acts as a "sponge," quickly absorbing and storing floodwaters, then releasing them slowly back into the stream and groundwater. Restoring forests along headwater streams means more storm flow is captured and retained higher in the watershed.

Riparian forest buffers also reduce flood damage as they capture sediments. The sedimentation of streams contributes to flood damage by filling in streambeds and increasing the frequency and depth of flooding and by increasing the volume of flood waters, as well as by causing additional damage itself.