Mass. Gen. Laws ch. 49 § 9
If lands of different persons, required under this chapter to be fenced, are divided by a river, brook, pond or creek, and one of the occupants refuses or neglects to join in making a partition fence, or they disagree respecting the same, the fence viewers shall, upon application, forthwith view such river, brook, pond or creek; and if they determine that it is not sufficient as a fence, that it is impracticable to fence on the true boundary line without unreasonable expense, and that a partition fence is required, they shall, after notice to the parties, determine how or on which side the fence shall be set up and maintained, or whether partly on the one side and partly on the other, as to them may appear just, and shall reduce their determination to writing; and if either party refuses or neglects to make and maintain his part of the fence according to such determination, it may be made and maintained as before provided, and the delinquent party shall be subject to the same costs and charges, and they shall be recovered in like manner.
Mass. Gen. Laws ch. 49, § 9