The post is OK here.
You have two choices. One, let them stay on land. If the water temp is over 72F, this is probably a safer option. And if they are eating well, they will "bulk up" better on land than in water. Two, you can reduce their island area gradually until they have no choice but to be aquatic. Be sure they have plenty of plants and wet resting places. They can adapt to this, but if the temp is warm, it's probably better to wait. When the weather cools and the days shorten, they will go back to the water on their own.