They changed the name of the town, remember? Because the townspeople wanted to distance themselves and their community from the atrocities committed by Jason Voorhees? This was all explained in FRIDAY THE 13th VI: JASON LIVES.
In this film, the part of Crystal Lake, aka Forest Green, was portrayed by the small town of Covington, Georgia, which looks the same today as it did 35 years ago. At least the downtown does.