Located within the borders of the municipality is the Indian reserve of Ebb and Flow 52, as well as the 60,000 m (6 ha) Margaret Bruce Beach Provincial Park, located 12 km (7.5 mi) east of the town of Alonsa, on one of a series of sand ridges that extend the length of the west side lake. The park is currently under lease to a private operator but development plans include a provincial campground and day use facility.
The incorporation of Alonsa on 1 January 1945 was as a Local Government District (LGD). It received rural municipality status on 1 January 1997.
In the 2021 Census of Population conducted by Statistics Canada, Alonsa had a population of 1,210 living in 492 of its 659 total private dwellings, a change of -3% from its 2016 population of 1,247. With a land area of 3,006.17 km (1,160.69 sq mi), it had a population density of 0.4/km (1.0/sq mi) in 2021.
