N.H. Rev. Stat. § 72:11-a
When a city, town or district has acquired, or acquires property in another city or town for the purpose of water supply or flood control which for any reason has been exempt from taxation, such property, if yielding no rent, shall not be liable to taxation therein but the city, town or district so holding it shall annually pay to the city or town in which such property lies either a sum equal to that which such place would receive from taxes from such land, without buildings or structures thereon, as determined by the commissioner of revenue administration, or the alternative payment permitted by RSA 72:11, II. Such payments shall be made as provided in RSA 72:11.
RSA 72:11-a
1965, 9:1. 1973, 544:8. 1977, 501:3, eff. Sept. 12, 1977. 2013, 94:2, eff. June 20, 2013.