[ScreamingViking]

It's probably more the concern that the creeks may flood during heavy rains, especially if blocked by debris (e.g., the Spencer Creek tributary that goes beneath York Rd. and then under Cootes Drive has flooded in the recent past when trees and branches blocked the culverts)

Now that we tend to get localized storms that produce a lot of water in short spans of time the Conservation Authority is probably averse to the risks. Though that pretty much hamstrings any development in eastern Dundas unless it's on a hill.