lake Saint-Louis

{{Short description|Lake in Quebec, Canada}}

{{redirect|Lac Saint-Louis|the electoral district|Lac-Saint-Louis}}

{{Infobox lake

| name = Lake Saint-Louis
{{small|{{native name|fr|Lac Saint-Louis}}}}

| image = St. Louis Lake shore - panoramio.jpg

| caption = Lake St. Louis at St-Anne-de-Bellevue looking towards Île Perrot

| image_bathymetry = Lake st-louis.png

|pushpin_map=Quebec

| caption_bathymetry = Location map

| location = Montérégie region, southwestern Quebec

| coords = {{coord|45|24|05|N|73|48|51|W|region:CA-QC_type:waterbody_source:CGNDB_scale:250000|display=inline,title}}

| type = Natural

| inflow = Beauharnois Canal, Saint Lawrence River, Ottawa River, Saint-Charles River

| outflow = Saint Lawrence River

| catchment =

| basin_countries = Canada

| length =

| width =

| area =

| depth =

| max-depth =

| volume =

| residence_time =

| shore =

| elevation = {{convert|21|m|ft|abbr=on}}

| islands =

| cities = Montreal

}}

Lake Saint-Louis ({{langx|fr|Lac Saint-Louis}}, {{IPA|fr|lak sɛ̃ lwi|pron}}) is a lake in southwestern Quebec, Canada, at the confluence of the Saint Lawrence and Ottawa rivers. The Saint Lawrence Seaway passes through the lake.

Lake St. Louis is a widening of the St. Lawrence River in the Hochelaga Archipelago. It is also fed by the Ottawa River via the Lake of Two Mountains at Sainte-Anne-de-Bellevue, the Beauharnois Canal, the Soulanges Canal, the [[Saint-Louis River (Beauharnois)|

Saint-Louis River]], and the Châteauguay River.

The lake is bounded to the north and the east by the Island of Montreal, by Beauharnois-Salaberry, Roussillon, and Vaudreuil-Soulanges. The town of Beauharnois with its power-dam and canal lie to the south.

The West Island shore is mostly built up with private houses, but it includes some parks and clubs such as the Pointe-Claire Canoe Club, and the Pointe-Claire Yacht Club. Islands in the lake include Dorval and Dowker Islands. Lake St. Louis is the second of three fluvial lakes on the St. Lawrence River; upstream of it is [[Lake Saint Francis (Canada)|

Lake Saint Francis]], and downstream is Lake Saint Pierre. Lake St. Louis has an average flow of {{convert|8400|m3/s|cuft/s}}.[http://ec.gc.ca/stl/default.asp?lang=Fr&n=09C5A944-1 Environment Canada - fluvial lakes of the St. Lawrence] {{webarchive|url=https://web.archive.org/web/20140708171732/http://www.ec.gc.ca/stl/Default.asp?lang=Fr&n=09C5A944-1 |date=2014-07-08}}

The lake has many species of fish, including yellow perch.

A small map by Samuel Champlain of 1611 names the lake. The same year, Champlain reported that a young man named Louys was drowned in what is now known as the Lachine Rapids, and in 1870 Charles-Honoré Laverdière stated that the rapids, and later the lake, were named in honour of the drowned man. A 1656 Jesuit account describes a crossing «Lac Saint Louys».{{cite web|title=Lac Saint-Louis|url=http://www.toponymie.gouv.qc.ca/ct/ToposWeb/fiche.aspx?no_seq=57085|publisher=Commission de toponymie|accessdate=25 June 2014}}

In 2014 there was a report of fecal coliform flowing into the lake from a Beaconsfield creek,{{Cite web|url=http://www.cbc.ca/news/canada/montreal/beaconsfield-s-st-james-creek-contaminated-with-high-levels-of-fecal-coliform-1.2841689|title=Beaconsfield residents had no idea backyard creek was polluted with fecal coliform|website=www.cbc.ca|access-date=2016-04-09}} and of PCBs flowing into it from a Pointe-Claire industrial site.{{Cite web|url=https://montrealgazette.com/news/local-news/west-island-gazette/pointe-claire-pays-435000-cleanup-bill-at-pcb-site-on-hymus|title=Pointe-Claire pays $435,000 cleanup bill at PCB site on Hymus|website=Montreal Gazette|language=en-US|access-date=2016-04-09}}