"In theory, we will need to purify this spring. But do you think we could do something like that? If Alice had come we would be able to without a problem." The thought that Gil had was to send someone back to bring help this way.
"If we go back and get her we might not be able to get to the root of the problem. We need to get to the water elves first. If they need help we should help them first." In Walker's mind, the people were priority. For the chance that they needed help or not, it would be better to speak to them. If the group brought someone to purify the area without any communication with the water elves, it could cause future issues with relationships.