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TextPerennial Stream Mapping Project
Project Background | Chesapeake Bay Preservation Ordinance |
Quality Control/Quality Assurance Methodology and
Results | Perennial Stream Classification
Protocol
Project Background
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In Fairfax County, a perennial stream is defined as a body of water flowing in a natural or man-made channel year-round, except during periods of drought. The Perennial Stream Mapping Project was initiated in September 2001 to address concerns that all perennial streams were not being protected under the county's Chesapeake Bay Preservation Ordinance, Chapter 118 of the Fairfax County Code. At that time, the county's ordinance only listed perennial streams as those streams which were depicted as perennial on the U.S. Geological Survey topographical maps. Those streams as well as wetlands, tidal wetlands, and tidal shores were included within Resource Protection Areas. These areas perform certain ecological and biological processes indicative of maintaining good water quality. Resource Protection Areas are vegetated riparian buffer areas, which include land within a major floodplain and land within 100 feet of the aforementioned water bodies. These buffer areas are important in the reduction of sediments, nutrients, as well as the other adverse effects of human activities, which could potentially degrade these systems and those downstream. Under the county's old Chesapeake Bay Preservation Ordinance, if streams were not identified as perennial on the U. S. Geological Survey map, they did not warrant a Resource Protection Area.
The Chesapeake Bay Local Assistance Department recognized
difficulties with the use of the U. S. Geological Suvey maps. In
December 2001, the Chesapeake Bay Local Assistance Board adopted
amendments to the state's Chesapeake Bay Preservation Area
Designation and Management Regulations. The revised state
regulations became effective on March 1, 2002. The revisions
include a requirement to perform site-specific surveys using a
scientifically valid method to identify water bodies with perennial
flow. The state regulations allow localities some latitude in
developing their own definition of perennial streams and protocols
for identifying them in the field. |
Chesapeake Bay Preservation Ordinance
To ensure compliance with the state's revised Chesapeake Bay Preservation Area Designation and Management Regulations, the county has initiated and completed a Perennial Streams Mapping project. Beginning with the development of a protocol to identify the breaking point between perennial streams and intermittent streams (streams that do not flow during drier periods of the year), the county set out in March 2002 to accurately map all streams in Fairfax County. By October 2003, the field work was completed and the new Resource Protection Area maps were generated.
- Fairfax County's Chesapeake Bay Preservation Ordinance
- Understanding the Chesapeake Bay Preservation Ordinance Amendments - Important Information for Fairfax County Homeowners (PDF)
- Virginia Chesapeake Bay Local Assistance Department Regulations
Quality Control/Quality Assurance Methodology and Results
As part of the Perennial Streams Mapping Project, a Quality Control/Quality Assurance study was conducted throughout 2004, to check the accuracy and precision of the perennial stream determinations.
The following report presents the methodology and results of the study, as well as recommendations and next steps. In order to view these documents, you will need to have Adobe Reader installed on your computer.
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Quality Control/Quality Assurance Methodology and Results Report (PDF) Appendix A - Resource Protection Area Review and Additional Site Data for:
Appendix B and C - Perennial Streams Field Classification Protocols and Data Sheet Appendix D and E - Glossary of Terms and List of Acronyms and Abbreviations (PDF) |
Perennial Stream Classification Protocol
The field protocols used to identify perennial streams are available in PDF format. In order to view these documents, you will need to have Adobe Reader installed on your computer.
- Field Protocol (PDF)
- Data Sheet (PDF)
For more information on the Perennial Streams Mapping Project, please contact the Stormwater Planning Division, 703-324-5500, TTY 711.
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