when ice jams occur during spring ice break. The RMWB warns citizens of the potential for sudden flash floods "especially in populated areas adjacent to the Athabasca River, Clearwater River and Christina River." Water levels have been monitored by the Water Survey of Canada since 1970 (WSC station 07CD004). During the spring months there is increased monitoring of the "Clearwater River to the south of the urban service area to provide warning of an ice break" and the "Athabasca River upper basin, local river levels, precipitation and overall weather patterns." The Clearwater River, designated as part of the Canadian Heritage Rivers System, flows from its headwaters at Lloyd Lake in northwest Saskatchewan into northeast Alberta before joining the Athabasca River at Fort McMurray. "The lack of significant oil sands developments means that the Clearwater River can be used as a baseline river system to provide information on the variability and characteristics of natural systems." Demographics Federal census In the 2021 Census of Population conducted by Statistics Canada, the Regional Municipality of Wood Buffalo had a population of 72,326 living in 25,934 of its 30,451 total private dwellings, a change of from its 2016 population of 71,594. With a land area of , it had a population density of in 2021. In the 2016 Census of Population conducted by Statistics Canada, the Regional Municipality of Wood Buffalo had a population of 71,594 living in 25,659 of its 30,713 total private dwellings, a change of from its 2011 population of 65,565. With a land area of , it had a population density of in 2016. Municipal census The permanent population of the Regional Municipality (RM) of Wood Buffalo according to its 2021 municipal census is 75,555, a change of from its 2018 municipal census permanent population of 75,009. In addition, the 2021 municipal census counted a shadow population of 30,504 non-permanent residents for a combined population of 106,059, while the 2018 municipal census counted 36,678 non-permanent residents for a combined population of 111,687. Ethnicity Language Immigration Wood Buffalo is home to almost 2,000 recent immigrants (arriving between 2001 and 2006) who now make up more than 3% of the population. About 21% of these immigrants came from India, while about 10% came from each of Pakistan and the Philippines, and about 9% came from Venezuela, and about 8% from South Africa, about 6% from China, and about 3% came from Colombia. Religion