Loon Pond Water Treatment Plant Wastewater Treatment Facility Wastewater Treatment Facility Wastewater Treatment Facility Water Main installation on West Main Street (provided by Hillsborough Historical Society - Manahan-Phelps-McCulloch Photographic Collection.) Water Main installation on West Main Street (provided by Hillsborough Historical Society - Manahan-Phelps-McCulloch Photographic Collection.) Water Main installation on West Main Street (provided by Hillsborough Historical Society - Manahan-Phelps-McCulloch Photographic Collection.)