The reservoir was built at the end of the 19th century for the Newcastle and Gateshead Water Company.

Much of the reservoir is fringed by mature coniferous plantation, although birch and beech also grow here with bramble and raspberry providing much of the field layer.

[1] One of Colt Crag's main attractions are the great crested grebes, and there is also a colony of 20-30 pairs of house martins that return each year to nest under the eaves of the boathouse.

The rough grassland adjacent to the site provides ideal breeding habitat for the cuckoo, meadow pipit, whinchat, and wheatear.

[1] Badgers are known to use the site during the summer months, and both pipistrelle and noctule bats may be seen feeding around the sheltered north eastern end of the reservoir.