In the 2021 Census of Population conducted by Statistics Canada, the RM of Lake Lenore No. 399 had a population of 506 living in 179 of its 279 total private dwellings, a change of -13.8% from its 2016 population of 587. With a land area of 714.17 km2 (275.74 sq mi), it had a population density of 0.7/km2 (1.8/sq mi) in 2021.[7]
In the 2016 Census of Population, the RM of Lake Lenore No. 399 recorded a population of 587 living in 214 of its 290 total private dwellings, a 9.5% change from its 2011 population of 536. With a land area of 723.53 km2 (279.36 sq mi), it had a population density of 0.8/km2 (2.1/sq mi) in 2016.[4]
The RM of Lake Lenore No. 399 is governed by an elected municipal council and an appointed administrator that meets on the second Wednesday of every month.[3] The reeve of the RM is Jean Kernaleguen while its administrator is Jolynne Gallays.[3] The RM's office is located in St. Brieux.[3]