On July 4, 1999, a powerful wind storm, or derecho, swept across Minnesota, central Ontario, and southern Quebec. Winds as high as knocked down millions of trees, affecting about within the BWCAW and injuring 60 people. This event became known officially as the Boundary Waters – Canadian derecho, commonly referred to as "the Boundary Waters blowdown". Although campsites and portages were quickly cleared after the storm, an increased risk of wildfire due to the large number of downed trees became a concern. The U.S. Forest Service undertook a schedule of prescribed burns to reduce the forest fuel load in the event of a wildfire.