Upon graduation, Don worked for Houston Lighting & Power as an Accountant and Financial Analyst. In 1987, he assisted with the acquisition of Paragon Cable and served as the Accounting Manager for the Tampa Bay division. In 1990, Don joined the Pasadena Water & Power Department as a Principal Rate Analyst. In 1994, he moved south to Anaheim Public Utilities Department where he served as an Accounting Manager until he was promoted to Financial Services Manager, where his responsibilities included accounting, finance, budget, rates, and strategic planning. In May 2006, Don joined the City Of San Bernardino, Water Department as Director of Finance.

Don has served as a coordinating committee member at the Intermountain Power Project and as a finance committee member at the Southern California Public Power Authority.