The scientists studied how changes in water flow in southeast Florida affect groundwater quality. They used computer models and water quality data to find an area with low dissolved solids in the Biscayne aquifer under the Atlantic Coastal Ridge. This clean groundwater is from before canals were built in the 1950s, not from the canals. It will take about 70 years for the clean groundwater to mix with the high-salt water in the water-conservation areas. The salty water will stay in those areas due to slow movement and mixing with the clean groundwater. The type of ground and how water moves can change how groundwater quality will change when it mixes with surface water.