I looked up the easement on line at the Belknap Registry of Deeds.
http://nhdeeds.com/belknap/BeHome.html
Book: 0816 Page: 0749
There is a reference to the camp if it is destroyed by fire or casualty it can be replaced to a size no larger than 25% of its original size. Also the "camp" can be maintained but cannot be materially changed in its character. There are other restrictions such as no cutting of trees or removing timber withing 50' of the mean shoreline.