Published April 2008. Reviewed October 2013. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalog
The work upon which this publication is based was supported by funds provided by the United States Department of the Interior as authorized under the Water Resources Research Act of 1964, as amended. OWRR Project No. B-016-ORE.