The Eglwys Nunydd is a large reservoir

Reservoir

A reservoir , artificial lake or dam is used to store water.Reservoirs may be created in river valleys by the construction of a dam or may be built by excavation in the ground or by conventional construction techniques such as brickwork or cast concrete.The term reservoir may also be used to...

 in Margam

Margam

Margam is a suburb of Port Talbot in the Welsh county borough of Neath Port Talbot, Wales, close to junction 39 of the M4 motorway.- History :...

, South Wales

South Wales

South Wales is an area of Wales bordered by England and the Bristol Channel to the east and south, and Mid Wales and West Wales to the north and west. The most densely populated region in the south-west of the United Kingdom, it is home to around 2.1 million people and includes the capital city of...

 originally constructed to provide water for the large steelworks

Port Talbot Steelworks

Port Talbot Steelworks is an integrated steel production plant in Port Talbot, Wales capable of producing nearly 5 million tonnes of steel slab per annum. The majority of the slab is rolled on-site at Port Talbot and at the Newport Llanwern site to make a variety of steel strip products. The...

 at Margam and specifically for cooling water for the cold rolling mills at the eastern end of the works. Much of the water for the hot end of the plant is abstracted from the Rivers Afan

River Afan

The River Afan is a river in southwest Wales whose river valley formed the territory of the medieval Lords of Afan. The town of Aberavon grew up on the banks of the river, and was later subsumed by the larger centre of population known as Port Talbot...

 and the Ffrwdwyllyt as they flow through the dock feeder.

The lake supports a managed trout

Trout

Trout is the name for a number of species of freshwater and saltwater fish belonging to the Salmoninae subfamily of the family Salmonidae. Salmon belong to the same family as trout. Most salmon species spend almost all their lives in salt water...

 and coarse fishing

Coarse fishing

Coarse fishing is a term used in the United Kingdom and Ireland for angling for coarse fish, which are those types of freshwater fish other than game fish . The sport and the techniques used are particularly popular in the United Kingdom and mainland Europe.-History:The term "coarse fishing"...

 fishery and is also used for dinghy

Dinghy

A dinghy is a type of small boat, often carried or towed for use as a ship's boat by a larger vessel. It is a loanword from either Bengali or Urdu. The term can also refer to small racing yachts or recreational open sailing boats. Utility dinghies are usually rowboats or have an outboard motor,...

 sailing

Sailing

Sailing is the propulsion of a vehicle and the control of its movement with large foils called sails. By changing the rigging, rudder, and sometimes the keel or centre board, a sailor manages the force of the wind on the sails in order to move the boat relative to its surrounding medium and...

.