Many parts of the world have an increasing population, and a commensurate need for more water. But how to increase the supply when hydrogeologic information is limited? The USGS San Diego Hydrogeology project faced this quandary in 2001. What to do first, what to do next? How to make progress when funding and staffing are uncertain?
Now 10-plus years later, we have a three-dimensional geologic framework model of the coastal area, 13 multiple-depth monitoring wells, thousands of water-quality analyses, and a regional groundwater flow model. A broad perspective in space and time has allowed us to define where recharge occurs, where fresh water is located and why, how the groundwater system has evolved over the past thousands of years, what the approximate unused yield of the coastal aquifer is, and how our methods can be applied to other coastal areas with increasing demands for more water.