Actually, just looking at the image, and where it is on the map, it IS coastal. Florida-Everglades-type coastal. Due to their incessant work, the water would be mostly clean (though still a bit murky) and if you notice: There's a greenish haze all across. The city probably started off being built atop that hill, above all the muck, and slowly expanded. Granted, the water does look too clean for "bubbly green swamp", however, maybe it's just a bubbly swamp with greenish gas (their power source) leaving it have an overall greenish hue.
Also, check out those two houses in the bottom right, they look like they're right off of a greenish swamp, rather than next to grassland.