Frequently Asked Questions

The Virginia Department of Environmental Quality has listed Meadow Creek and a segment of the Rivanna River downstream as ’impaired waterways’. Impairment in these waters is due in part to excessive sedimentation from stream bank erosion. Restoring Meadow Creek and enhancing and preserving the forested buffer and wetlands along the creek will aid in reducing sedimentation and filtering stormwater runoff entering Meadow Creek and the Rivanna River.

As rivers and streams flow, they naturally carve their course through the landscape - carrying a certain amount of sediment downstream. In natural conditions, a river will alter its course over time, as it creates natural meanders and floodplains that slow its flow during storm events, dissipating energy and reducing erosion. But in urban environments, large areas are covered with impervious surfaces. As a result, water cannot infiltrate into the ground, and instead drains into stormwater systems, and then creeks and rivers, much faster than it naturally would.

This rapid drainage and increased quantity of runoff results in high peak flows in waterways. The matter is made worse by the fact that many urban waterways have been "channelized" or straightened in order to maximize develop-able land, reducing the natural capacity of the waterway to slow down and dissipate the water’s energy. The result is severe erosion of stream banks, scouring of stream beds, and excessive sedimentation. Sediment loading is recognized as one of the greatest threats to the Rivanna River and the Chesapeake Bay; sediment carries pollutants that have bonded to it into waterways, suspends in the water column and blocks sunlight from aiding in the growth of submerged aquatic vegetation, clogs the gills of fish (sometimes suffocating them), and eventually destroys aquatic habitat in streambeds when it settles.

A buffer is a vegetated strip alongside a stream. The streamside zone, also called the riparian zone, exercises very strong controls over stream conditions and is therefore vital to the health of the entire river basin. It is in this zone, where stream water makes its most intimate contact with the channel bed and banks, that much of a stream’s cleansing action and nutrient processing occurs.

• Buffers dissipate stream energy - streamside vegetation reduces the power of the stream by slowing water down through friction. Doubling the speed of a stream’s flow results in the erosion of four times as much soil.
• The vegetation acts to filter pollutants from surface runoff. For example, buffers can remove excess nitrogen and phosphorus (two harmful pollutants) from artificial fertilizers, which in large quantities can cause harmful algae blooms that deplete oxygen levels in waterways.
• The plants, trees, and root systems filter and trap sediment, keeping it out of the waterway where it can negatively impact aquatic habitat, while building and maintaining the stream banks.
• Buffers improve water infiltration. If vegetation is removed, water flows downstream at a much higher velocity, decreasing the amount that soaks into the riparian area and streambed. Water that soaks into these areas recharges groundwater supplies, which in turn enhances stream flow levels throughout the year and in drier seasons.
• Buffers provide vital wildlife habitat and food sources for aquatic organisms as well as shade to keep water temperatures cool.
• Buffers can reduce flood damage. When small streams are in their natural state, they absorb significant amounts of rainwater and runoff before flooding. However, when a landscape is altered, the runoff can exceed the absorption capacity of the stream.