Wascana Lake is located in downtown Regina and represents probably the best paddling option for residents. Access to the lake is best at Willow (docks at bottom right of map), just north of the Broad Street bridge. There is a fair bit of parking and three options for putting in.
The best option is the beach immediately south of the main parking lot (by the bridge). It is sandy, gentle and an easy carry (no picture--sorry). There is also a concrete boat launch right there, but launching kayaks and canoes seemed prohibited.
There is also a paddling centre (that rents) that has a beach and docks, including a sandy boat launch. There are also public washrooms here.
The perimeter of the lake is about 4km. Access to the southern half of the lake (south of the bridge) is prohibited as it is a migratory waterfowl sanctuary. Powered boats appear to be allowed on the lake, at least in some circumstances (several pontoon boats were moored), and there were also sailboats on the water.
There are a couple of interesting islands to paddle around and the lake is set next to the provincial legislature (which is pretty). There is also a paved walking trail around the lake.
The lake was marked for racing with buoys when I was there. There were also a lot of kids in canoes on the water. Although the flags were standing straight out, I didn't find the lake too choppy (its gets some shelter from the surrounding park). It is directly on the flight path from the airport so expect planes overhead!
The lake was lousy with waterfowl (mostly geese) when I was there. A friend who paddles suggests the lake gets nasty in later summer. The water was pretty murky while I was there but seemed free of leeches (at least at the beaches).