The Chehalis River winds its way through the valley in which the city resides, and is joined by a tributary, the Newaukum River. This confluence of waters, along with the intersections of tributaries and railroads within Chehalis, helped the city become known as "The Maple Leaf City". Both the Chehalis and Newaukum rivers are prone to flooding during periods of abnormally heavy or persistent rain, and the lowlands from the freeway westward are particularly susceptible to inundation. A variety of local groups, scientists, and government have organized a partnership called "The Chehalis Basin Strategy" to propose and research a combination of plans along the Chehalis River to mitigate flooding and to restore aquatic habitat for local Chinook salmon. The current proposal outlines several flood control reduction measures, including levee improvements at the local airport and a flood retention dam in Pe Ell.
