Darlington Dam, also referred to as Lake Mentz, is a gravity type dam situated in the Addo Elephant National Park confining the Sundays River, near Kirkwood, in the Eastern Cape, South Africa.

The construction experienced many setbacks, including lack of materials and machinery, with shortages caused by the First World War, unsuitable labour (returning soldiers), the 1918 influenza epidemic, bubonic plague, very difficult logistics and drought.

The dam wall was raised by 1.5 m in 1935 and again by 5.8 m (total capacity 327,628,072 m3) in 1951/52 to cope with the loss of storage volume.

The serious drought of 1966 and 1967 emphasized the necessity to commence work on the Skoenmakers Canal (capacity: 22 m3/s) to link the Great Fish River to Darlington Dam as soon as possible.

In view of an expected increase in irrigation below Darlington Dam and the demand for water in the Port Elizabeth metropolitan area, it was decided to replace the Wellington Grove pumping station with De Mistkraal Weir upstream of Wellington Grove and a short section of connecting canal to the beginning of the Skoenmakers Canal.