Atty. Ma. Mercedes V. Dumagan is a Certified Public Accountant, Lawyer, and Civil Service Executive Eligible (CSEE). Her career started at the Department of Environment and Natural Resources Region XI, as Attorney III under the Legal Division in October 1999. She was in charge of the handling of numerous civil, criminal, and administrative cases including arbitration proceedings for land claims and conflicts. With her outstanding performance as Atty. III in the agency, she was designated as the Assistant Regional Director for Legal Public Affairs in the year 2002. 

      On the 17th day of November 2003, Atty. Dumagan was promoted to Financial and Management Officer II and became the Chief, Administrative Officer of the Finance Division in the year 2005.  On July 14, 2015, she was promoted to Provincial Environment and Natural Resources Officer of Davao del Sur. One of her achievements was during the Mt. Apo Fire Incident in April 2016 where the PENRO Davao del Sur joined forces with the National Disaster Risk Reduction and Management Council – Incident Management Team on the Fire implementation and tactics to combat the Mt. Apo Fire.

      A year after, Atty. Dumagan was designated as the OIC, ARED for Management Services and became full-fledged Director III, ARED-MS of DENR Region XI on March 23, 2018. As ARED for MS, she supervised all the management activities and concerns in the region, securing effective and efficient delivery of services to the people and clientele. Her accomplishments include resolving and fast-tracking of the numerous cases in the Legal Division, expediting the hiring and promotion in the Region as the Chairperson of the Human Resource Merit Promotion and Selection Board (HRMPSB), cascading Region XI-Environment and Natural Resources Academy where she was one of the resource person. In addition, Atty. Dumagan was the chairperson of the DENR XI- Quality Management System Implementation and supervised in maintaining the QMS ISO 9001:2015 Certification. She is the GAD Focal Point System Chairperson, the highest-ranking lady official in the region. 

      For the period September 24, 2020 up to November 20, 2020, she was given the chance to supervise and implement the policies, laws, and all the plans and programs of DENR Region XI as she was designated as the OIC, Regional Executive Director.

     On June 23, 2023, she was again designated as OIC, Regional Executive Director per Special Order No. 2023-389 signed by Secretary Maria Antonia Yulo-Loyzaga. Atty. Dumagan is a member of the Integrated Bar of the Philippines, the Davao Lady Lawyers Association, and she is a past lady chancellor of Sigma Tau Mu Sorority of the Fraternal Order of St. Thomas More.