page_title: Twelve Mile Creek (Ontario)
section_title: Watershed description
hierarchical_section_title: Twelve Mile Creek (Ontario) / Watershed description
caption_attribution_description: English: Decew Falls at the start of Bruce Trail.
context_page_description: Twelve Mile Creek 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.
context_section_description: 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; 
  Upper Twelve Mile Creek
  Lake Gibson System
  Richardson Creek
  Francis Creek
  Dicks Creek
  Lower Twelve Mile Creek
  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) which 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
  Richardson Creek flows through mostly agricultural, but rapidly urbanizing land in the western part of St. Catharines.  It is about 10.5 km in length.  It combines with Francis Creek  and empties into the Twelve Mile Creek at Martindale Pond, very close to its outlet.  These two sub-watersheds therefore do not contribute to water flow on the great majority of the Twelve Mile Creek.
  The Dicks Creek sub-watershed originates near the escarpment in a residential area, but afterwards flows into industrial and commercial areas.  It flows through the abandoned second Welland Canal, passing through the stone locks which once carried ships, before entering a tunnel.  It emerges from the tunnel and joins with the main branch of the Twelve Mile Creek immediately beside Highway 406, and not far from the downtown buildings of St. Catharines. 
  The lower portion of Twelve Mile Creek, while historically navigable as part of the second Welland Canal, is now a fast flowing river with rapids and a wide, swift water course.  Almost all of the water in this portion of the creek (98 to 99%) is from the Welland Canal by way of the Decew Falls generating stations.  The creek empties into Martindale Pond - a small artificial lake near the shores of Lake Ontario created to permit navigation on the first Welland Canal.  This body of water also served as the route for the second and third canals and remains of locks from the second and third canals are still visible.  Martindale Pond is now the site of the Royal Canadian Henley Regatta course.  The water flows over a weir into Port Dalhousie harbour, and finally out into Lake Ontario between two long piers.
caption: The Decew Falls, Niagara Escarpment, St. Catharines
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