The water of Lachlan Swamp is usually clearer than the stormwater ponds in the Parklands. Iron pyrites present in the soil oxidise to release sulfur dioxide and cause the spring water to be slightly acidic and therefore clearer. The water also filters up to the surface through sand, contributing to its clearer appearance.
Lachlan Swamp is inhabited by a Grey-headed Flying-fox colony that was first established in February 2010 in response to an exceptionally large food shortage event thought to be caused by drought and vegetation clearing affecting large parts of coastal NSW. During this food shortage event, flying-foxes were observed to establish new colonies in urban areas closer to food resources. Since its establishment in 2010, the colony continues to grow annually.