2017: I revisited the place on June 27. The pool is open but they are currently renovating the splash pad section. I was told it should be done by mid-July.
The Petticoat Creek Conservation Area's main asset used to be a huge wading pool nicely surrounded by green lawn and small trees. It took me over 350 full steps to circumnavigate the edge of this blue swim spot. Four summers ago, I revisited the place to see the new water area. Where the huge pool used to stand, I found three vast wading pools and a large shallow pool with one beach-like entrance. They also added a huge splash pad, which must look like a giant "rain forest" from a preschooler's point of view. Kids were having a blast! Note that the photos present the splash pad before the renovation. I'll revisit later this summer to update the pictures. If you miss the giant pool, don't! You can still go to Bronte Creek Provincial Park to enjoy their immense shallow pool.
With older kids, you might want to walk along the paved bike trail, with a few viewing points to admire the lake. They have officially closed the dirt trail along the cliff (but you can still peek into parts of it at your own risks). The paved path will lead you in 15 minutes to the bridge running over the stream giving its name to Petticoat Creek Conservation Area. (To see more pictures and additional regarding Frenchman's Bay Park further down, at the end of the waterfront trail, read my post describing my summer 2015's visit to Petticoat Creek and surroundings).