The Sumas River used to flow into Sumas, a large lake in British Columbia, which was part of the Fraser River's floodplain. In the 1920s, the lake was drained to create more fertile land for Canadian farmers. Swift Creek, a tributary of the Sumas River, is contaminated with naturally occurring asbestos-laden sediment from the slow-moving Swift Creek Landslide. In July of 2009, the Whatcom County Health Department and the Washington Department of Health updated their health advisory to include the northern portion of the Sumas River to be contaminated due to Swift Creek's asbestos.