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Catherine, If you have a blog you should be using structured data. But in any case that couldn't be the reason of the drop. I am guessing competitors using some shady techniques to outrank you and others or perhaps lack of content. I do see only 18 pages were indexed. Having a blog and posting regularly can help you. For example posting experiences from your customers? or any extra info you can provide on the locations you offer skiing (I don't know). Do a little research and see what's missing in other pages and get your hands on it. In any case, if the site outranking you are spammy, you can always report them to Google, they don't pay too much attention, however, you could then throw a thread in the Google Webmaster Help forums (if you didn't do any backhat link building, which apparently you didn't. Once you start creating good content, over time you will earn links which ultimately and combined will give you an edge over your competitors. That just needs time, time and more time. Hope that helps!