The lake is bound in the east by Mandurah Road and in the west by the suburb of Cooloongup, with the reserve south of the lake stretching to Safety Bay Road, to the south of which Lake Walyungup is located.
Like Lake Walyungup, Lake Cooloongup is thought to be drying because of reduced rainfalls. Depths of both lakes fluctuate from 0.5 to 3.5 metres, with the permanent pools of Lake Walyungup being the deepest points. Both lakes are also increasing in salinity, with Walyungup being more saline than Cooloongup. Unlike Lake Cooloongup, which has a groundwater outflow towards the sea, Lake Walyungup is a closed system, with water from the lake discharging through evapotranspiration only. Both lakes have small freshwater wetlands on their western edge, which is made up of dunes, while the eastern edge is formed by a limestone ridge.[3]
A warning sign at Lake Walyungup highlighting the risk of unexploded ammunition
The Lakes Cooloongup and Walyungup continue to be of spiritual significance for the local indigenous population as the place where the Sea Waugal laid her eggs. Walyungup, in the Nyungar language, means "place where Nyungars talk", leading to the conclusion that the northern lake was a place for children while the southern one was for adults.[3]
Lake Cooloongup as well as Lake Walyungup, Port Kennedy Scientific Park and Lark Hill, all within Rockingham Lakes Regional Park, are potentially contaminated with unexploded ordnance, having been used as artillery range by the Department of Defence in the era around World War II.[3]
