Quarry Lake is one of those "locals" lakes in the Canadian Rockies. It's where you'll find people walking their dogs and just enjoying the scenery. There are picnic and park benches to sit and look up at Ha Ling Mountain and the Little Sister.
Quarry Lake has many visitors, especially on weekends in the summer, and sadly, many don't clean up after themselves. Make sure to pack out what you bring in and always Leave No Trace. There are plenty of bear-safe trash bins around.
While the park around the lake is free, the parking around the lake is not. Hourly rates are fairly high for visitors.