Question: Chemainus River is located in a Canadian province that is part of which bioregion ?
Context: Westholme is a community located in the Chemainus River Valley alongside the Island Highway, between Chemainus and Duncan in British Columbia, Canada.  It is part of the Chemainus Land District in the District Municipality of North Cowichan. Mount Whymper is a mountain located on Vancouver Island, British Columbia.  It is the highest point in Canada located south of the 49th parallel and is located between the headwaters of the Chemainus River and the South Nanaimo River 14 km north of Honeymoon Bay. The Chemainus River is located on southern Vancouver Island, British Columbia, Canada.  Its source is in the Vancouver Island Ranges, and it flows eastwards to the Strait of Georgia near the town of Chemainus, British Columbia.  The valley that surrounds the river additionally includes the communities of Crofton and Westholme as well as the Halalt First Nation Reserve. The Halalt First Nation is a First Nations tribe located on a reservation near Chemainus in southeastern Vancouver Island, British Columbia, Canada.  The historical territory of the Halalt people is the lower Chemainus River Valley and Willy Island, which is offshore from today's town of Chemainus. Brooklyn Sanctuary is a 600 km² nature reserve in north-east Queensland, Australia, less than 100 km north-west of Cairns.  It is owned and managed by the Australian Wildlife Conservancy by which it was acquired in 2004.  It is located on the boundary of the Wet Tropics bioregion and Einasleigh Uplands bioregion on the Mount Carbine Tableland.  The landscape varies widely from rugged, rainforested peaks of up to 1,200 m altitude, with an annual rainfall of 4,000 mm, to drier lowland plains in the upper reaches of the Mitchell River with less than 900 mm.  It is important for the conservation of upland endemic species.  Part of the property is inscribed on the World Heritage List. British Columbia is the westernmost province of Canada, with a population of more than four and a half million people.  It is located between the Pacific Ocean and the Rocky Mountains.  British Columbia is also a component of the Pacific Northwest and the Cascadia bioregion, along with American states Alaska, Idaho, Montana (western portion), Oregon and Washington. The Doug flag, also referred to as the Cascadian flag or the Cascadia Doug flag and nicknamed "Old Doug" or simply "the Doug", is one of the primary symbols and an unofficial flag of the Cascadia bioregion, which roughly encompasses the U.S. states of Oregon and Washington, the Canadian province of British Columbia, and other parts of North America's Pacific Northwest.  It was designed by Portland, Oregon native Alexander Baretich in the academic year of 1994-1995. The Saint John River (French: "Fleuve Saint-Jean" ; Maliseet: "Wolastoq"( )) is a river, approximately 418 mi long, located principally in the Canadian province of New Brunswick, but also in and arising from the province of Quebec and the U.S. state of Maine.  It forms part of the Canada–United States border in two different places along its length.  The river drains an area of approximately 55000 km2 , of which slightly more than half is located in New Brunswick.  Along that portion of the Atlantic shoreline of North America that lies between the St. Lawrence River and the Mississippi River, the Saint John River is the second longest waterway; only the Susquehanna is longer.  It has been nicknamed the "Rhine of North America" for its scenery.  The river is regulated by hydro power dams located at Mactaquac, Beechwood, and Grand Falls, New Brunswick. The Disabled Sailing Association of British Columbia (DSA-BC) is a Canadian not-for-profit organization that enables people with disabilities to take part in a sport it promotes as “accessible and inclusive.”  It is located in Vancouver, BC, and has affiliated branches in Victoria, Chemainus and Kelowna. The Cascadia official soccer team is the official association football team representing the Cascadia region of the United States and Canada and is controlled by the Cascadia Association Football Federation (CAFF).  The team will be composed of players from the U.S states of Oregon, Washington and the Canadian province of British Columbia.  The stated mission of the team is "...to allow Cascadia as distinct cultural entity, isolated bioregion and growing society with common interests to be represented at the international level in the sport we are all passionate about."  CAFF is a member of ConIFA.  Cascadia is not a member of FIFA or any confederation or subconfederation as the region is wholly a part of both the United States or Canada.  However, CAFF is not opposed to those organizations and sees itself coexisting as a non-FIFA regional representative team.
Answer: Cascadia bioregion