The anti-dragon zones around High Hall and the harbour can not be lowered; you can only enter in human form. The anti-dragon zone in Stone's fortress can be removed by destroying a generator in that fortified area.
The only thing in Rivertown Gorge is Kali's flying fortress. There is no way to get lower or reach any other areas, and if you enter on foot from the fjords, you need to be quick about transforming when you enter the gorge, because that first step is a big one...
