At a rated capacity of 500 MW, the Holyrood Thermal Generating Station (HTGS) is the second largest generating source on the island portion of the province. The oil-fired station, which is owned and operated by Newfoundland and Labrador Hydro, generates electricity at times when power demands exceed the capacity of the hydro generating facilities on the island. Environmental programs for HTGS include ambient air and stack emission monitoring, operation of a wastewater treatment plant and an on-site controlled solid waste landfill, and community involvement through community liaison committee meetings. In addition, Newfoundland and Labrador Hydro own and operate 25 diesel generating plants on the island and in Labrador. Many of these provide continuous power to isolated rural communities which are not joined to the island's interconnected power grid.