Coiner began operating his family farm in 1974.[1] He later became Chairman of the Twin Falls Canal Company and
President of Milner Dam. He also served as Chair of the Upper Snake River Basin Advisory Group, on the Twin Falls City Water Planning Committee, and as a member of the Southeast Twin Falls Transportation Corridor Study.[3]
First elected to the Idaho Senate in 2004, Coiner served as Vice-Chair of the Senate Commerce and Human Resources Committee during his entire tenure in the Senate. He also served on the Senate Committees on Health and Welfare, on Resources and Environment, and on Agricultural Affairs. He was also a member of the Senate Natural Resources Interim Committee, Senate Mental Health and Substance Abuse Interim Committee, Council of State Governments River Governance Group, and Pacific Northwest Economic Region.[3]
