Washington County, Oregon
Modified Ordinance 738 Filed Jan 27th, 2011
On page 55:
The light distribution pattern selected shall be that which gives the most cost-effective luminaire spacing for the design light level. Light dispersion above the 90 degree (horizontal) plane shall meet the dark sky requirements.
Go to: http://www.co.washington.or.us and search for "WASHINGTON COUNTY ROAD STANDARDS"