A part of East Main Street in Riverhead will be without public water service for two hours Monday from 3 to 5 p.m.
The Riverhead Water District and Petrocelli Contracting plan to install a new water main to serve the 100-room hotel and exhibition center being built at the Atlantis Marine World aquarium.
Those facilities are scheduled to open later this year.
The affected area will run from the aquarium to Riverside Drive, just west of Riverhead Town Hall.
Work crews have been preparing the site for the past week to reduce the length of the disruption, which will affect several private businesses and some town offices.