People used to dive in Candlewood lake and Squantz Pond in western Connecticut. It also had flooded towns. When I started diving in the 1980s I would hear stories about some of the building still being intact. Nowadays I don't hear about those any more. Most of the buildings were razed prior to the flooding. But I suppose some of them were missed because of issues like those described in your article. The buildings I heard about were supposedly intact, but the wood had become very spongy. Farm equipment, cars, roads, stone walls, foundations and other objects are still there. Wood can survive for decades in fresh water, however, when exposed to air during drought, will deteriorate quickly. Divers that told me about diving those old building said they kept their locations secret because some people were diving the and vandalizing them with their knives. If you want to find old buildings, you probably could use a sonar fish, if you know someone that owns one.
Having puttered around the bottom of a Connecticut lake on a couple of occasions, visibility is pretty rough. Conditions may have been better 30 years ago before all of the development around the lakes and all the lawn fertilizer that washes into the lake.
