Project Summary Sheet

Project Title: Simulated Effects of ASR Injection in the Floridan Aquifer System Near Lake Okeechobee, Florida - A First Approximation

Project Start Date: July 2002 Project End Date: September 2003

Web Sites: na

Location (Subregion): Northern half of Lake Okeechobee to southern Counties in Georgia, and from west to east coast in Florida

Funding Source: USGS's Greater Everglades Science Initiative: PBS FY 03

Principal Investigator: Nick Sepulveda

Project Personnel: Principal Investigator

Supporting Organizations: USGS (PBS)

Associated / Linked Projects: na

Overview & Objective(s): CERP's Aquifer Storage and Recovery (ASR) Project proposes to inject and then withdraw up to 1.0 billion gallons per day (Bgal/d) of surface water into and out of the Upper Floridan aquifer (UFA) during wet and dry weather conditions at selected sites near Lake Okeechobee (LO). The objective of this study is to assess the potential effects of injecting and then withdrawing 0.5 Bgal/d of water into the UFA in the northern half of LO on the potentiometric surface of the Floridan aquifer system (FAS).

Status: Locations of injection wells around the northern half of LO, used in simulations, were established. Model simulations were completed. Fluxes across model boundaries were computed, head buildups were contoured, and effects of projected 2020 withdrawals were simulated. Final figures are being generated.

Recent & Planned Products: A letter of transmittal, with simulation results, and a brief explanation of the completed work, will be sent to Ronnie_Best@usgs.gov and aetorres@usgs.gov by July 28, 2003.

Relevance to Greater Everglades Restoration Information Needs: The impact of the injection of 0.5 Bgal/d along the northern half of LO is analyzed by (1) generating a contour map of the simulated head buildups on the potentiometric surfaces of the UFA and Lower Floridan aquifer (LFA), (2) computing simulated changes in vertical leakage among the hydrogeologic units in the FAS, and (3) assessing changes in the recharge and discharge map to the UFA, all resulting from the proposed ground-water injections.

Key Findings:

• The generation of the head-buildup map for the UFA and LFA, when conditions before and after the injection of 0.5 Bgal/d are simulated, indicated that heads in these aquifers were increased, north of LO, up to Orange County, where the one-foot contour of head buildup occurred.
• The largest simulated flux leaving the model area along the lateral boundaries (along the southern limit of the model) was 16 ft³/s (cubic feet per second), with fluxes ranging from 3 to 16 ft³/s.
• The largest simulated decrease in downward leakage from the surficial aquifer system (SAS) to the UFA occurred in the Lake Wales Ridge physiographic region; downward leakage or recharge was reduced from 30 to 22 inches per year (in/yr). In terms of reversing the recharge pattern, a cell in the Okeechobee Plain physiographic region had the largest shift, where a downward leakage from the SAS (recharge) of about 3 in/yr was simulated to be an upward leakage of 3.5 in/yr (from the UFA to the SAS) as a result of the injection of 0.5 Bgal/d along the northern half of LO.