The CMA is located in the winter rainfall region.
River flow is variable, with high peak flows in winter and low summer flows.
Rainfall is also distributed unevenly, varying from very low annual rainfall on the Cape Flats to high rainfall on mountain catchments. Considerable modification of rivers by the construction of dams has occurred to meet the water demands for residential, agricultural, industrial and commercial activities. Urban growth has also expanded into the floodplains of many streams and rivers and discharges of wastewater and effluents have altered both the hydrodynamic and water quality characteristics of many rivers, wetlands and vleis. In order to provide a detailed description of the state of the environment, the focus has been to identify and examine specific issues within an overall theme in order to examine the state and pressures on each of these issues more thoroughly.