Assessment of Storm Water Discharge to a Karst Groundwater System

Sulphur Springs is a second magnitude spring and discharges an average of 25 MGD of groundwater into the Hillsborough River. The spring is used as a supplemental source of drinking water for the City of Tampa. Rapid urbanization has occurred throughout the Sulphur Springs drainage basin and has significantly stressed the local hydrologic environment. Prior to the 1970’s, storm water in Curiosity Creek flowed south to the Blue Sink Complex where the surface water entered the Blue Sink and traveled through solution channels in the Upper Floridan Aquifer to Sulphur Springs. In the mid-1970’s trash and debris accumulated in the sinkholes and reduced the sinkhole flow capacity and caused extensive flooding.

SI was contacted to investigate options to restore the Blue Sink Complex back to its natural state and restore the groundwater flow to Sulphur Springs. A network of over 20 monitoring wells were installed in the Blue Sink Complex and surrounding areas to determine the hydraulic connectivity between the surface water in Curiosity Creek and the receiving groundwater system and their relationship to the discharge of Sulphur Springs. Long-term continuous monitoring of the water elevations in the network and regional stress tests were performed to delineate the groundwater flow regime through analysis of the discontinuities in the potentiometric surface of the aquifer. SI concluded that removal of the blockage in the solution channels have reduced the feasibility of restoring the system to its natural state. The primary focus of the investigation has shifted to the southern portion of the Sulphur Springs drainage basin where numerous sinks are still connected to the flow system and need to be preserved.

Aerial with sinkhole and well locations