|Location||Perth, Western Australia|
|Native name||Keiermulu (Nyungar)|
|Designation||Lake Monger Reserve|
|Surface area||0.7 km2 (0.27 sq mi)|
|Shore length1||4.5 km (2.8 mi)|
|1 Shore length is not a well-defined measure.|
Located less than 5 kilometres (3.1 mi) from the city of Perth and situated alongside the Mitchell Freeway, it runs approximately north-west to south-east towards the Swan River and consists of 70 hectares (170 acres) of mainly open shallow water, with an island of 1.3 hectares (3.2 acres) in the south-west corner. The 110 hectares (270 acres) of lake and the surrounding parklands are known as the Lake Monger Reserve.
A 3.8-kilometre (2.4 mi) paved walking/cycling track encircles the lake. Car parking, playground equipment, and barbecue facilities are also provided.
After European settlement, it became known as either Large Lake or Triangle Lake (based on its roughly triangular shape) before being named Monger's Lake in 1831. In April 1932 it was changed to its current name of Lake Monger.
Little is known about the use of the lake by the Noongars prior to the British settlement other than the area was known to be within the area inhabited by those people. Given its geographical features, it could have been used regularly as a significant camping and hunting site with black swans and other wildfowl as well as turtles, frogs, gilgies and mudfish hunted as food.
Associated with the lake is the Wagyl, part of Noongar mythology. The myth describes the track of a serpent being, who in his journey towards the sea, deviates from his route and emerges from the ground which gives rise to Lake Monger. The lake and a significant part of the reserve are registered with the Department of Indigenous Affairs as an Aboriginal heritage site of historic and mythological significance to the Aboriginal people.
The lake was originally part of a series of freshwater wetlands running north from the Swan River along the coastal plain for approximately 50 kilometres (31 mi). Lake Monger was grouped with the Georgiana Lake and Lake Sutherland (both near Mitchell Freeway, near Sutherland and Newcastle streets) and Herdsman Lake and together the area made up what was known as The Great Lakes District.
European settlement led to many of the wetlands areas being drained for land reclamation to take advantage of the fertile soil for farming enterprises, and for expansion of parks and recreation areas. Lake Monger and Herdsman Lake are the last two major wetlands remaining close to the city. The City of Perth itself sits on an area of reclaimed wetlands. It is thought that between 49% and 80% of the wetlands on the coastal plain have been drained, filled or cleared since 1832.
Other lakes and swamps in the immediate northern vicinity of the early Perth township were Lake Kingsford (site of the current Perth railway station), Lake Irwin (Perth Entertainment Centre) and further north were Stone's Lake (Perth Oval), Lake Poullet (First Swamp, part of what is now Birdwood Square), Lake Thomson (Mews Swamp, between Lake, Brisbane and Beaufort Streets) and Lake Henderson (parts of what is now Robertson Park and Dorrien Gardens). Further north still lay Second Swamp (Bulwer Street, east of Lake Street), Third Swamp (Hyde Park) and Three Island Lake and Smith's Lake (now Charles Veryard Reserve). Many of these lakes formed a natural interconnected drainage system that found its way into the Swan River at East Perth through Claise Brook.
In 1833, water draining from Lakes Kingsford, Irwin, Sutherland and Henderson was used to drive a water-driven mill located in Mill Street.
A reed island was constructed in the 1960s to provide a summer refuge for birds. Thirty eight species of birds have been sighted including black swans, cormorants, spoonbills and pelicans.
The lake also supports southwestern snake-necked turtles, large skinks, and two species of frogs. Fish common to the lake are all introduced species including goldfish, carp, mosquito fish and English perch.
Vegetation in the 1800s comprised swampland trees; Melaleuca rhaphiophylla, Banksia littoralis, and Eucalyptus rudis. Xanthorrhoea (balga or grasstree), rushes, wattle and tea tree were the common flora, but with land reclamation, rushes were removed to plant lawns and construct sandy beaches. None of the banksia and few paperbarks remain and trees are now generally confined to a narrow strip surrounding the shoreline, mainly on the northern and eastern sides.