WPTA 2007-01 Water Protection Ordinance

Stream Buffers:

 

Current and Proposed Buffer requirements in Albemarle County

Albemarle County has authority to require the preservation of stream buffer vegetation from the Commonwealth’s 1988 Chesapeake Bay Preservation Act.  That legislation required localities in the Tidewater area to incorporate water quality protection measures into their land use planning, including requiring the preservation of stream buffers.  In addition, the legislation provided localities that are not a part of Tidewater Virginia the opportunity to voluntarily adopt these water quality protection requirements.  In 1991 Albemarle County became the first non-Tidewater locality to voluntarily adopt a local Chesapeake Bay protection ordinance, and a major component of the ordinance is the requirement to preserve vegetated stream buffers.  In keeping with the Bay Act, Albemarle County requires the buffer to be a minimum of 100 feet wide on both sides of the stream.  The existence of wetlands and floodplains associated with the stream can significantly widen the required buffer. 

 

·         Perennial Streams - Buffers are currently required along all perennial streams in the County.  A perennial stream is one that flows year-round during a year of normal precipitation.  Perennial streams have typically been identified as a stream that is shown as a solid blue line on the United States Geological Survey (USGS) 7.5 minute topographic maps (1:24000 scale).  However, in 2003 the Chesapeake Bay Preservation Act was amended to also allow the “use of a scientifically valid system of in-field indicators of perennial flow” to identify perennial streams (Section 9VAC10-20-80D) because it was recognized that streams with perennial flow exist that may not be shown on USGS maps.  Following this amendment, the Virginia Chesapeake Bay Local Assistance Department (CBLAD) crafted the guidance “Determination of Water Bodies with Perennial Flow” dated September 2003.  This guidance presents various options that are approved by CBLAD for making perennial stream determinations, and this is the guidance referred to in the County’s proposed amendments for the definition of perennial stream in Section 17-104 (32) of the Code.  The proposed amendment to the County Code will update our requirements in accordance with the state enabling legislation.

 

·         Intermittent Streams - In addition to perennial streams, Albemarle County currently requires the preservation of stream buffers along intermittent streams in portions of the County that drain to water supply reservoirs or water supply intakes (water supply protection areas), and this is supported in the Chesapeake Bay Preservation Act.  An intermittent stream is one that has a defined bed and defined banks, and flows only part of the year in response to precipitation through near surface groundwater flow or from springs.  (These streams should not be confused with ephemeral streams which flow only a few hours or days following a single storm and have no stream buffer requirements under the County’s ordinance.) 

 

Intermittent streams have typically been identified as either a stream that is shown as a dashed or dotted blue line on the USGS 7.5 minute topographic map (1:24000 scale) or, if not shown on USGS maps, a stream that meets the County’s Design Standards Manual criteria for an intermittent stream.  Under the County’s criteria an intermittent stream must have a drainage area of at least 5 acres or be derived from a spring and have a defined streambed and defined streambank where the bed and channel materials are distinct from the surrounding valley or swale (e.g. the channel has a rocky stream bed versus matted down grass or an eroded ditch).  County staff currently provides in-field determinations of intermittent streams that are not shown on USGS maps at the request of property owners in water supply watersheds to determine the presence or absence of stream buffer requirements.

 

·         Proposed Requirements - The proposed amendment to Section 17-317 of the Code would extend stream buffer requirements to all intermittent streams in the Rural Areas, making the requirements in the Rural Areas equivalent to the current requirements in the water supply protection areas.  No change in buffer requirements would apply to the County’s designated development areas, where stream buffers would continue to be required only on perennial streams.  The rationale for requiring stream buffers on intermittent streams in the majority of the County is strongly supported in scientific literature.  Research has shown that riparian buffers are especially important along the smaller headwater streams which make up the majority of stream miles in any watershed.  These streams are most affected by land use that surrounds them, and have the most opportunities to receive pollutants, such as excess nutrients and sediment (Osborne and Kovacic 1993, Binford and Buchenau 1993, Hubbard and Lowrance 1994, Lowrance et al 1997). 

 

Because these smaller streams are most affected by the adjacent land use, they also have the most opportunities to benefit from the presence of streamside vegetation.  In addition to reducing the amount of nutrients, sediment, and other pollutants that reach a stream, riparian buffers provide food input (leaf litter) for macro invertebrates.  Macro invertebrates are tiny animals that live on the stream bottom and are an important link in the food chain in stream systems.  Buffers also provide critical shade for temperature control.  Removing riparian vegetation decreases available leaf litter and increases stream temperatures.  A less robust population of macro invertebrates can detrimentally affect the species richness and population of fish, and even minor changes in temperature can cause major changes in the fish community (Baltz and Moyle 1984).  Research shows that shading has the greatest impact on smaller streams (Osborne and Kovacic 1993) which indicates a need to establish and preserve buffers on smaller streams.

 

 

Literature References

            Baltz, D. M. and P. B. Moyle. 1984. The influence of riparian vegetation on stream fish communities of California. Pp 183-187 in R. E. Warner and K. M. Hendrix (eds), California Riparian Systems: Ecology, Conservation and Management. Berkeley, CA: University of California Press.

 

            Binford, M. W. and M. J. Buchenau. 1993.  Riparian greenways and water resources. In: Smith, D. S. and P. Cawood, eds. Ecology of Greenways. Minneapolis, MN: University of Minnesota Press.

 

            Hubbard, R. K. and R. R. Lowrance. 1994.  Riparian forest buffer system research at the Coastal Plain Experimental Station, Tifton, Georgia. Water, Air and Soil Pollution 77: 409-432.

 

            Lowrance, R., and 12 others. 1997. Water quality functions of riparian forest buffers in Chesapeake Bay watersheds. Environmental Management 21(5):687-712.

 

            Osborne, L. L. and D. A. Kovacic. 1993.  Riparian vegetated buffer strips in water-quality restoration and stream management. Freshwater Biology 29: 243-258.

 

 

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