Bribie Island has important groundwater that supports ecosystems and human needs. A new borefield is planned to extract more water due to population growth. The island has two aquifers separated by a layer of hard sand. The shallow aquifer is close to the surface and follows the land's shape, while the basal aquifer is deeper. If too much water is taken out, it could harm plants and allow salty water to intrude. Rainfall affects groundwater levels on the island. The island's climate is sub-tropical with high rainfall and evaporation rates. Water quality in the area could be affected by flows from creeks and groundwater discharge. The island's groundwater is mostly fresh, but near the coast it can be salty.