Guelph Lake, lake in Ontario, Canada

Guelph Lake is a large man-made reservoir in Ontario created in 1974 when a dam was built across the Speed River. The roughly 420-hectare area features two sandy beaches, over 10 kilometers of forested trails, more than 100 campsites with water and electricity, three boat launches, and facilities for picnicking and group gatherings. Only electric motors are permitted on boats, maintaining a quieter environment for paddlers and rowers.

The lake was created in 1974 when a dam was built across the Speed River to manage water flow and control flooding in the region. The dam also generates electricity for local needs, and over time the site has grown into an important recreational area managed by conservation authorities for community use.

The lake takes its name from the nearby city of Guelph. The Guelph Rowing Club, founded in 1998, has been based here since 2000 as home of the University of Guelph Gryphons rowing team, and a permanent boathouse was built on the shore in 2008. The Guelph Community Boating Club sails from the lake and is home to Snipe fleet 877, Canada's largest Snipe fleet, hosting regattas through the year.

The conservation area is closed in winter, when the lake and its grounds are off-limits. Two man-made sand beaches have changing facilities but no regular lifeguard patrol. Canoes, kayaks and johnboats with electric trolling motors are rented from the boathouse at the main beach; no outboard motors are allowed. About five kilometres of hiking and biking trails start inside the area, and a recreational trail follows the Speed River from downtown Guelph.

The Hillside Festival is held each year at an outdoor concert venue on a peninsula in the middle of the lake; its stage has a living roof covered in plants. The reservoir was created in 1974 by the Guelph Lake dam, and the site lies in the 1,608-hectare Guelph Lake Conservation Area.