The Chilliwack River was heavily used by the Northwest Boundary Survey of 1857-1862 as a means of accessing the
49th parallel north in order to survey and map the border between American and British-Canadian sovereignty. A number of the Chilliwack's tributaries cross the 49th parallel, including Liumchen Creek, Tamihi Creek, Damfino Creek, Slesse Creek, Nesakwatch Creek, and, from Chilliwack Lake, Klahailhu Creek and Depot Creek. Both American and British surveying parties established base camps on Chilliwack Lake from which they sent field parties through the Chilliwack drainage and east to the
Skagit River drainage. In addition, the
Whatcom Trail followed much of the Chilliwack River's course. Historically the Chilliwack River flowed north from
Vedder Crossing, over a broad
alluvial fan into the
Fraser River. In 1875, heavy rains caused a
log jam that diverted the river into two small streams called Vedder Creek and Luckakuck Creek, which caused hardship for the area's farmers. In 1882, a new log jam was deliberately created which caused the waters of several streams to shift course toward the west, flowing into the now-disappeared
Sumas Lake. A
freshet in 1894 caused this new course to become permanent, and compounded on the devastating 1894
Fraser basin flood. In the early 20th century, the diverted river was diked and channelized, and the Chilliwack River downstream of the Vedder Crossing was permanently diverted westwards into the
Vedder Canal to
artificially drain the Sumas Lake, and today the canal are renamed the Vedder River. The former interlaced
distributaries of the Chilliwack River below Vedder Crossing are now modified into the
Chilliwack Creek, which flows northwest
meandrously from
Sardis past
Downtown Chilliwack to empty into the Fraser River east of the
Chilliwack Mountain opposite the islands of the Fraser River Ecological Reserve. ==Recreation==