Beaver Creek is the main drainage in the park. All other streams (Highland and Cold Spring) flow into it or would if they contained enough flow to do so. Beaver Creek drains an area of approximately 46 square miles. It starts near Pringle and flows east into the park, and then continues southeast to join the Cheyenne River east of Buffalo Gap. However, the flow rarely makes it out of the park as it typically looses its entire flow when it reaches the outcrops of Pahasapa Limestone. This process plays a crucial role in recharging the Madison Aquifer. In April of 1998 I gaged Beaver Creek above and below the loss zone to determine how much of the stream was sinking and determined that the creek above the cave was flowing at 5.67 cubic feet per second (cfs) and below at 1.99 cfs. Thus, the loss zone was responsible for a loss of 3.68 cfs or 27.5 gallons per second. This means that in a 24-hour period 2.4 million gallons of water enter the aquifer via Beaver Creek.
In a 1986 study, Marsha Davis and Dr. Calvin Alexander injected dye into the stream to determine where the water was going. The injection point was where the stream was captured by the aquifer near the intersection of the Centennial and Beaver Creek trails. After one month dye showed up in the Park’s water supply well and persisted for several months, exemplifying the surface to subsurface hydrologic connection.In the fall of 1990, the USGS installed a stream level recording gage on Beaver Creek just below the confluence with Cold Spring Creek. This station is still in operation and has provided us with over 15 years of continuous flow data