Mass. Gen. Laws ch. 165 § 4B
Any water company or corporation subject to this chapter having franchise rights encompassing an entire city, town or district may, subject to determination by the department after notice and a public hearing as to the public convenience and necessity, and with the advice and consent of the department of environmental protection, take by eminent domain under chapter seventy-nine or acquire by purchase or otherwise and hold the waters, or any portion thereof, of any pond, brook, spring, stream or groundwater sources within its franchise territory not already appropriated for purposes of public water supply, and any water or flowage rights connected therewith, and such lands, rights of way and other easements as may be necessary for collecting, storing, holding, purifying and treating such water and protecting and preserving the purity thereof, and for conveying the same to any place within its franchise territory.
Mass. Gen. Laws ch. 165, § 4B