The scientists studied the water systems on North Stradbroke Island. They found two main groundwater systems, one that connects across the island and another that is more localized. The water levels in the island's groundwater mound have varied over the years, reaching a high point in 1975 and a low point in 2007. The water from the groundwater system flows into wetlands, creeks, and even Blue Lake. Rainfall is the main source of water recharge, with different parts of the island receiving varying amounts of rain each year. The researchers created a detailed model of the island's hydrology to better understand how water moves through the soil and vegetation.