The roodeplaat-reserve website has the following info:
Located about 22km north-east of Pretoria the Roodeplaat dam was
originally called the 'Pienaars Rivier Dam' when it was constructed
in 1956 to supply the surrounding land owners with water. It has
developed into an important water source for the Pretoria area and
after commissioning the Roodeplaat water treatment plant in 2006,
the dam augments the supply of water to the northern areas of
Tshwane through the Montana, Wonderboom and Magaliesberg reservoirs
and is used as a direct water supply to the Doornpoort area.
The Department of Water Affairs and Forestry (DWAF) delegated
the management of the Roodeplaat dam area to the devision of Nature
Conservatioon of the Transvaal Provincial Administration (TPA) in
1972. The Transvaal Provincial Administrations mandate was to
develop the area as a nature reserve and out-door recreation
facility for the city population. The reserve was proclaimed in
1977.
Roodeplaat dam is a well known destination for bird watching,
game viewing and a range of water sports including fresh water
angling.