Twelve Mile Creek (Ontario)

Twelve Mile Creek
River
Country	Canada
Province	Ontario
Region	Southern Ontario
Regional municipality	Niagara
Part of	Great Lakes Basin
Source	Unnamed pond
- location	Pelham
- elevation	194 m (636 ft)
- coordinates	43°02′59″N 79°17′16″W / 43.04972°N 79.28778°W / 43.04972; -79.28778
Mouth	Martindale Pond
- location	St. Catharines
- elevation	85 m (279 ft)
- coordinates	43°10′43″N 79°16′21″W / 43.17861°N 79.27250°W / 43.17861; -79.27250Coordinates: 43°10′43″N 79°16′21″W / 43.17861°N 79.27250°W / 43.17861; -79.27250
Basin	178 km2 (69 sq mi)
Location of the mouth of the creek in Ontario

Twelve Mile Crick is a waterway located on the Niagara Peninsula in the Regional Municipality of Niagara in Southern Ontario, Canada. Its headwaters are located in the town of Pelham, encompassing some of the most unspoiled and natural areas of Niagara area. The creek's lower reaches flow through urban areas of Thorold and St. Catharines, and have been heavily altered by human activity for almost two centuries.

Twelve Mile Creek is named because its outlet to Lake Ontario is located approximately 12 miles (19 km) from the Niagara River. It drains a watershed of approximately 178 square kilometres (69 sq mi). This may be grouped into six sub-watersheds;

Of these, only the Upper Twelve Mile Creek can truly be considered to retain any significant degree of its natural state. This sub-watershed branches out into dozens of small streams and drains flowing through Short Hills Provincial Park and St. John's Conservation Area, as well as various natural, agricultural and lightly developed areas. The area containing the headwaters is known as the Fonthill Kame Delta Complex and was formed from debris left behind by glaciers as they retreated approximately 12000 years ago. This area has the highest elevation, and contains the only identified cold water streams identified in the Niagara region. The area provides habitat for many bird species, including Acadian flycatcher, hooded warbler, Louisiana waterthrush and Kentucky warbler.

Lake Gibson is not a natural feature, but rather an artificially created reservoir. Township maps from the later half of the 19th century show a meandering stream flowing through this area (Beaverdams Creek) and plunging over the Niagara Escarpment at Decew Falls. This is the site of Morningstar Mill (still in existence today) who used this stream for power. This stream was subsequently dammed to provide a reservoir for hydroelectric generation at the Decew Falls Generation Station. The landscape was further altered with various channels and canals to improve flow to the generating station, and with the creation of additional reservoirs. Lake Gibson receives almost all of its water supply from Lake Erie via the Welland Canal. This reservoir also serves as the domestic water supply for the City of St Catharines