The highlighted area, from ninth line to 407, is part of Milton. However, it touches the boundary of Mississauga and it wanted the land.

Well, it got it (pretty much).

In return, Milton will receive $2 million and Halton $1.29 million (to compensate these municipalities for lost property tax revenue). 

It’s a good deal for Mississauga, since it can do something with the land, and a good deal for Milton, it got paid for something it wouldn’t have done anything with anyway.  A true win-win situation.