"Riparian Buffer Width, Vegetative Cover, and Nitrogen Removal Effectiveness: A Review of Current Science and Regulations" Published
An EPA report has recently been published on a water resource issue that may be relevant to your agency and your interests. This report, "Riparian Buffer Width, Vegetative Cover, and Nitrogen Removal Effectiveness: A Review of Current Science and Regulations", provides a synthesis of existing scientific literature on the effectiveness of riparian buffers to improve water quality through their inherent ability to process and remove excess anthropogenic nitrogen from surface and ground waters.
The following URL will take you to a pdf of the report.
http://www.epa.gov/ada/download/reports/600R05118/600R05118.pdf