I've seen aerial photos of the place, and it was a thing in the earliest ones I have access to (1947), and even seems to have survived a decade beyond Hurricane Hazel in 1954, existing into the 1960s. The place was called, I gather, "The Willows", and started off as a set of cottages, at least some of which were winterized into homes by the early 1950s.
Above is how the place looked in 1947. The road running left and right toward the bottom of the image is Lawrence Avenue. As you can see, at the time, it followed the curve of the land into the valley, crossed Highland Creek with a one-lane bridge, and climbed back out again. At the eastern end of the valley, a road eased down into the flood plain on the northeast side, and here you can see the loop of the little community. At that time, the central area appears to have been an open common, sporting a baseball diamond.
Here's the same view in 1953, about a year before Hurricane Hazel hit Toronto. The place is really coming into its own, and you can see that cottages, or more likely home, have begun to fill up the north end of the central common area.
Here's how The Willows looked in 1957, a few years after Hurricane Hazel. I'm surprised anyone was still living down there after the flood. As you can see, the site was scoured right up to the edge of the ring road, and all the structures on the west side of the street are gone. There's also obvious construction going on at the bridge site. About this time, the one-lane bridge was being superseded with a temporary Bailey bridge capable of accommodating two-way traffic.
Here's the view in 1962. The double-lane bridge is in evidence but it's still a meander down into the valley and back. It appears there were still people living, or at least vacationing, down in the flood plain at least this late in history. The arrival of suburbia is pronounced now in the encroaching wide streets and sidewalks and dozens of houses now crowding The Willows on both sides.
1971. It's all over in spades. All the buildings of The Willows are gone, replaced by a park with a trail through it. Apartment buildings tower over a Lawrence Avenue with four lanes and a circa 1965 bridge that vaults across the valley and ignores it.
Same view in 1983. Not much has changed.
1992. Trees are clearly beginning to retake the field. Highland Creek has noticeably begun rebelling against the channel it was forced into in the 1960s, eating into the eastern bank again.
Here's how the place looks today. That bit of open green just to the left of where the trails meet is where I brought Larry to try out his metal detector. Apparently it works... if finding old pop cans is to be the measure of success. :)
While I couldn't find any pictures of the community itself, the City of Toronto Archives does have a number of pictures of the valley with, first, the Bailey bridge being set in place at the end of the 1950s, and then the 1965 bridge (called "The Willows Bridge") under construction for contrast.
This view faces west from the opposite crest. We parked somewhere in this vicinity last Sunday, just off the to the right. The turn down into The Willows would have been behind the embankment on the right.
This view faces south, looking at the old one lane bridge carrying Lawrence Avenue across Highland Creek, and the "new" Bailey bridge superseding it. This is just a bit south of where Larry was sweeping with his metal detector on Sunday.
This view faces north toward the bridges. To my real surprise, Highland Creek here flows northward, away from Lake Ontario. In other words, you're looking downstream in this shot, not upstream as I would have expected.
This north of the bridges, looking west. I believe that manhole you see is the same one I was standing beside last Sunday, watching Larry try out his metal detector. The manhole cover I saw, however, was dated 1969, so if I'm correct, then the cover was replaced. It's kind of strange seeing this view and contrasting it with what I saw in March, 2015, over 55 years later.
Given the shadow cues, this view faces west down Lawrence Avenue, with the valley behind (obviously) the photographer, looking in the direction of Markham Road somewhere in the distance.
The following are views from 1965, when the modern Willows Bridge was being constructed.
This view faces west from the eastern edge of the bridge. You can compare this to the second c.1959 photo.
This view faces east from the other lip of the valley and compares roughly to the first c.1959 photo above. Though that water tower appears in both sets of photographs, it's long gone today. It doesn't appear in the 1971 aerials taken just six years later.
This view faces west.
This view faces east, taken on the north side of Lawrence Avenue. The extensive terraforming would have effectively erased the original road down to The Willows, somewhere there at the upper left. The community itself would have been off the left.
Similar view, taken on the south side of Lawrence Avenue.
Further south, this view faces northeast. The flood plain seen through the pillars of the bridge was where The Willows stood until just before this bridge was built. You can also see the area where Larry and I were at the river's edge on the far side last weekend.
Both this view and the one below face east. The modern slope on the left on the far bank is where Larry and I came down the path on Sunday. Roughly at the edge of the frame on the left is where we tried out the metal detector.
Views today...
Facing east.
Facing west. The path into what was The Willows is on the right just beyond the construction vehicle.