COTTONWOOD — Sarah Karjala and Scott Patterson announce their engagement. Parents of the couple are Merle and Linda Karjala of Cottonwood and Don and Patti Patterson of Arnold, Md. Karjala is a 2001 graduate of Marshall High School and a 2006 graduate of the University of Wisconsin, Madison, with a degree in civil engineering. She is also a 2008 graduate of Montana State University, Bozeman with a master of science in civil engineering. She is a traffic engineer with the Montana Department of Transportation. Patterson graduated in 2000 from Broadneck High School in Annapolis, Maryland. He attended Montana State University, Bozeman, and graduated in 2004 with a degree in geology. In 2008 he obtained his master of science in geology from Montana State University, Bozeman. He is employed as a public drinking water specialist at Montana Department of Environmental Quality. The couple plans a March 10, 2018, wedding in Helena, Mont.