Check out Clarke County's lighting ordinance:
http://www.clarkecounty.gov/planning/zoning.html
Open main Zoning Ordinance document. Outdoor lighting ordinance is section 6-H-11, or enter outdoor lighting in search box
Virginia Section of the International Dark Sky Association
"The Virginia Section of the IDA is dedicated to preserving and restoring Virginia's dark night skies, for public and natural welfare, with thoughtful regard for security and visibility." - Laura Graham
