The deal with the Matterhorn is this: Roughly a decade ago, the Matterhorn was in very bad shape. It was examined and found to be so damaged that tearing it down would probably have been the cheapest option. Fortunately however, the cheap option was not chosen. Instead of forever destroying the Matterhorn, it was decided that every year it would be given a lengthy refurbishment and in that way slowly fixed. So every year different parts of the track are redone, portions of the mountain are rerocked, this year the waterfall was fixed up in addition to the mysterious hole being cut at the top and airgates being installed at loading.
It's scheduled to be reopened the 23rd of November, but the paving project fell behind due to rain, so they're in a bit of a hurry to get it all finished.