Hollis Reservoir is located in Valencia - East Trinidad - nestled among the foothills of the northern range appearing as a sea among the hills. First commissioned in 1936, Hollis is the oldest of its kind in Trinidad and Tobago. It was built under the authorisation of Sir Claude Hollis, a past Governor of Trinidad and Tobago, from whom it got its name.
The reservoir was constructed by damming the Quare River, which enters the reservoir in a majestic split series of waterfalls that constantly replenish the lake from which an unfailing supply is drawn.

The journey to the reservoir leads through the quiet pasture lands of Wallerfield and Aripo, past the crossroad at Valencia. The final passage takes you through the hills, along a winding roadway fringed with ferns, trees and the whisper of water from the river that flows out of sight. As one passes the water treatment plant located at Hollis Reservoir, there still isn’t any sign of water. However, as the final hill is ascended, the absolutely gorgeous expanse of water, edged with towering firs is made visible.

The reservoir has a distinctly untouched beauty, as if all the man-made confusion of blocked river courses and the business of concrete dams and pipelines, has not disturbed the original charm of the quiet mountains and the gurgling of the mountain streams. This all combines to make Hollis by far the loveliest of the man-made dams in Trinidad and Tobago.

The water from the reservoir goes through a treatment process that is simple and precise. Chemicals are added to the water. These cause sediments in the water to cling together to form bigger and heavier particles. These particles are then removed when the water is passed through filters. The water leaving the filter is injected with chlorine to destroy any disease-causing bacteria before being distributed to areas in east Trinidad.

The water treatment facility at Hollis was upgraded in 2001 and now employs a state-of-the-art, filter backwash system. This allows plant operators to better monitor and control the water treatment process.
The new system eliminates the need for operators to make frequent visits to these sites to manually operate equipment.

The reservoir reaches its maximum depth at 20 metres (65 feet) and has an approximate capacity of 4,750,000 cubic metres or just over one (1) billion gallons. It is also capable of producing 38,180 cubic metres of water per day (8.4 m.g.d.).

The Hollis catchment area supports a wide range of animal life such as lappe, agouti, tattoo, howler monkeys, caiman, deer, wild hogs and a number of different types of snakes.

The area is also overlaid with a beautiful array of flowers, forming the ‘icing on the cake’ in this mix of nature and technology.

The pristine forest also provides a home for more than 90 species of birds, some of which are visitors from North and South America. This abundance of flora and wildlife has led to numerous ecological studies by naturalists and university students from Trinidad and Tobago as well as other countries.