He began his career in the Boston, Massachusetts area, but also worked in Colorado before settling into Oregon for the bulk of his career.

When he founded Teragan & Associates, Inc. in 2000, Terry's vision was to offer his clients tree management guided by leading edge research.  Teragan & Associates, Inc. continues to pioneer innovative techniques and research-based expertise. 

As the Principal Consultant for Teragan & Associates, Inc., Terry has guided the appropriate management of trees, shrubs and other horticultural plants on commercial, municipal, and residential properties.  Recently, he worked with Oswego Lake Country Club over a year-and-a-half to optimize fairways while minimizing tree removal on this old golf course founded in 1924.  He was also instrumental in the launch of the ISA's Tree Risk Assessment Qualification (TRAQ) that is now the standard for evaluating risk associated with trees.

Terry has served the International Society of Arboriculture (ISA) in several capacities. He has been a member of the Board of Directors since 2000, and has served as a member of the Certification Board of Directors since 2005.   He has been Chair to the Tree Risk Qualification Panel of Experts and Chair of the 2012 Portland ISA International Conference.  Terry was the Pacific Northwest Regional Education Coordinator for arborist professional development, has served on the Board for the Pacific Northwest and Rocky Mountain chapters in various positions for many years, and continues to be an active member of the American Society of Consulting Arborists. From 2013 to 2014, Terry reached the top and was elected President of the International Society of Arboriculture, where he spent a great deal of time traveling and serving tree communities as far as China and New Zealand.  

Terry was an instructor in the Horticulture program at Clackamas Community College in Oregon for ten years where he taught Arboriculture, Pruning, Tree Climbing, Landscape Installation and Chainsaw Use and Maintenance.  Terry's dedicated to education led him to help develop the Arboriculture program for the college.  Prior to starting Teragan & Associates, Inc. in 2000, he worked for 14 years at General Tree Services, Inc., where he was at different times, Manager of the Tree Division, Landscape Maintenance and Construction Divisions, and Business Development Manager.

Terry holds a Bachelors of Science Degree in Natural Resource Management from Colorado State University. He strives to continue his professional development through participation in several annual conferences, including the American Society of Consulting Arborists, the Annual International Society of Arboriculture Conference and Trade Show, the Oregon Community Trees Annual Summit, the Regional Training Conference of the Pacific Northwest Chapter of the International Society of Arboriculture, and the Oregon Golf Course Superintendents Association Winter Seminar.