N.Y. Town Law § 277
2. Additional requirements. The planning board shall also require that:
(b) Establishment of improvement district. If an improvement district has not been created for the area in which the plat is located, the town board may establish or extend an improvement district as provided in this chapter or in any applicable special law for the purpose of constructing or installing or acquiring without consideration such improvements shown on the map of any plat as the town board may determine.
(b) Any sums paid to the Suffolk county sewer agency pursuant to any provisions of this section, shall constitute a trust fund to be used exclusively for a future communal sewerage system which shall be owned and operated by a county sewer district, which district shall include the subject plat within its bounds. Such moneys and accrued interest, if any, when paid to such district, shall be credited over a period of time determined by the district, pro rata, against the sewer assessment of each tax parcel of the subject plat as may exist at the time of the payment of such moneys and accrued interest to such district. Provided, however, that if so directed by local law enacted by the Suffolk county legislature with approval of the county executive: