Partner, ROMA Design Group, San Francisco, CA; He retired from the firm before 1996.

Mountjoy retired to the Hayfork Community in Trinity County, CA. He served as a facilitator for the Hayfork Community Plan produced in 1996.

Mountjoy was active in the Trinity Fire Safe Council, c. 2010. (See the Watershed Center Newsletter, Hayfork CA, 2010)