Hillsborough Reservoir, which was commissioned in May 1952, by His Excellency Sir Hubert Elvin Rance, then Governor of Trinidad and Tobago, is the only impounding reservoir in Tobago.

Standing 870 feet above sea level, Hillsborough has a rustic beauty and an elegantly designed spillway which provides a safety outlet when the reservoir is too full. The reservoir has a maximum storage capacity of 1.02 million m³ and the water treatment plant located just below can produce up to 9,091m³ per day.
Water from the reservoir serves areas such as Mt. St. George, Concordia, Whim, Mary's Hill, Union and Les Coteaux.

The raw water from the reservoir passes through two strainers that clear the incoming water of large debris such as branches, twigs and leaves before entering the chemical house. Aluminium sulphate (alum) is added to make the suspended particles of silt and mud in the water coagulate and form large and heavier particles that sink to the bottom of the sedimentation (or settling) basins. The water is then filtered through layers of sand and gravel, a process that removes fine particles still in the water.

The final stage of the water treatment process is the addition of lime, to counteract the acidity of the water and the injection of chlorine to destroy any disease-causing bacteria.

Although construction of the Hillsborough Dam significantly changed the landscape, the catchment area and the reservoir still teem with an abundance of wildlife and a variety of flora. The twenty-eight (28) species of birds documented at Hillsborough will stir the interest of any bird watcher, while the lush vegetation especially the surrounding Canadian Pine trees, will make one's visit to Hillsborough quite memorable.