The work included a 3,887-yard (3,554 m) tunnel to allow the water to flow by gravity from the collecting area through a ridge of higher ground to the company's main reservoirs at Whittle Dene.

Land was purchased in 1880, and work started in 1884, using direct labour under the supervision of John Forster, the resident engineer.

Despite appalling weather in the winters of 1886 and 1887, and a poor understanding of soil mechanics which affected the construction of the dams, the reservoir was completed in 1889, with filling beginning in May 1889.

Newcastle and Gateshead had been provided with water from reservoirs at Whittle Dene, but the rapid growth of the towns in the mid-nineteenth century, coupled with several years of drought, meant that these were inadequate.

[3] Although the reservoir had been removed from the Act, they were empowered to build an aqueduct, which would intercept a number of streams between Hallington and Ryal, to the north west of Matfen.

An arrangement with the Duke of Northumberland was negotiated, to allow a brickworks to be built on his land, as a way of reducing transport costs for materials.

From sums of money paid to Cail, it would appear that he was employing 200 to 300 men on the contract, and the tunnelling progressed well, although there were difficulties at both ends, where the limestone was particularly hard.

[7] Shortly afterwards, much of the plant used on the project was put up for sale, including nine steam engines, 60 tons of bridge rails, 14 sets of pumps and two brick and tile making machines.

The main fault identified was a step at the western end, resulting in water standing to a depth of 18 inches (46 cm), which Cail claimed was due to inaccurate drawings.

The engineer for the company was John Frederick Bateman, but it was Thomas Hawksley who steered the bill through Parliament, so he may have been acting to protect the interests of Newcastle Corporation.

[3] The landowners were Henry H Riddell and Catharine Ann Tevelyan, and following negotiations with both parties, the company paid £9,500 for the land on which to construct the reservoir.

[12] Construction of the reservoir was aided by a narrow gauge railway, some 3 miles (4.8 km) in length, built to bring stone from Moot Law Quarry.

[15] John Furness Tone wrote a letter to Newcastle Council stating that the capacity of the reservoir was reduced due to the fissured nature of the underlying rock in the area.

[16] With the company struggling to meet the volume of water needed by the rapidly expanding towns of Newcastle and Gateshead, it decided to build a second reservoir at Hallington and two at Swinburn.

The bill was opposed by both Newcastle and Gateshead Corporations, although their objections were eventually withdrawn, and by John Gifford Riddell, on whose land the Swinburn reservoirs would be built.

[20] A source of stone was located near to Colt Crag reservoir, and a 2-mile (3.2 km) narrow gauge railway was built to transport it to the site.

In six years, some 516,000 cubic yards (395,000 m3) of earth had been moved, 33,000 waggons of stone had been transported along the railway, and 670,000 bricks had been manufactured and laid.

The Act also allowed them to build a narrow gauge railway from Matfen, at the eastern end of the tunnel, to Wylam, on the River Tyne, via Whittle Dene.

[23] A working site was established at the eastern end of the tunnel, with huts, offices, a canteen, spoil heaps and sidings for the railway.

[26] The aqueduct from West Hallington reservoir consistently suffered from leakage, and this was eventually solved by lining it with concrete, some time prior to 1911.

[28] The company had obtained an Act of Parliament in 1938 for various works, including a pipeline from Barrasford to West Hallington, to enable water to be pumped from the North Tyne, and repairs to the Ryal tunnel and aqueduct.

[33] The north-western part of Hallington Reservoir East is surrounded by mixed woodland, including evergreen varieties such as Scots pine and larch, with some native deciduous species, such as beech, willow, and sycamore.

The aqueduct that feeds into the reservoirs had been colonised by a healthy population of white-clawed crayfish Austropotamobius pallipes, when a survey was carried out in 2009.