Barangay San Agustin

Barangay San Agustin forms part of Dumalinao, a municipality in Zamboanga Del Sur, and is classified as a small barangay.

According to the 2020 Census of Population and Housing conducted by the Philippine Statistics Authority, Barangay San Agustin had a population of 844. This made it the 15th largest of 30 barangays in Dumalinao by population, placing it in the middle tier of the municipality. Residents of Barangay San Agustin accounted for approximately 2.56% of the total population of Dumalinao, which stood at 32,928 in the same census year.

The barangay recorded 1,008 residents in the 2015 intercensal count and 844 residents in the 2020 Census — a net change of -16.3%, consistent with a contracting settlement. The Philippine Statistics Authority classifies Barangay San Agustin as rural, a designation applied to barangays with lower population density and predominantly non-built-up land use.

Dumalinao is a municipality comprising 30 barangays, and serves as the governing unit directly responsible for local services in Barangay San Agustin, including public health, sanitation, peace and order, and civil registration. Within the wider province of Zamboanga Del Sur, which contains 779 barangays across its component cities and municipalities, Barangay San Agustin ranks 437th by 2020 population. Zamboanga Del Sur is classified as a 1st by the Bureau of Local Government Finance, a category that reflects the province's annual regular income.

Barangay San Agustin is governed by an elected Sangguniang Barangay composed of a Punong Barangay and seven kagawads, with the Sangguniang Kabataan representing the youth. The next BSKE, set for Monday, November 2, 2026, will elect officials to four-year terms as provided under Republic Act No. 12232.