The researchers studied the water flow in the Madison aquifer system near Rapid City, South Dakota. They used data from borehole logs and aquifer tests to figure out how water moves through the Minnelusa and Madison aquifers. They found that the Minnelusa aquifer has a transmissivity of 12,000 feet squared per day and a storage coefficient of 3 x 10-3. The Madison aquifer has a transmissivity of 17,000 feet squared per day and a storage coefficient of 2 x 10-3. The Minnelusa confining bed has a vertical hydraulic conductivity of 0.3 foot per day. The researchers also found that the porosity of the aquifers varies, with the Madison aquifer having the highest porosity at 35 percent.