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Groundwater Seepage in the Florida Keys

photo of snorkeler and coral reef
Project Investigator: E. A. Shinn

Project Start Date: 1996 End Date: 1999


The objective of this project it to measure the volume of groundwater seepage into the overlying marine environment of Florida Bay.

The Florida Keys contain 25,000 septic tank systems, approximately 5,000 cesspools, and 1,000 class 5 injection wells. Depth of injection wells ranges from 10 to 30 m. Excessive algal growth, coral diseases and both marine grass and sponge mortality is perceived to be caused by sewage nutrients leaking from groundwater on both sides of the Florida Keys. Determining the volume and composition of groundwaters seeping into the marine environment from the sea floor is vital to management decisions in the area. The data can be used for (1) planning future disposal systems, (2) modeling the hydrology of Florida Bay, and (3) understanding the distribution of benthic flora and fauna.

The objective of this study is to determine the volume and composition of groundwaters seeping upward through the rock water interface into Florida Bay and the coral reef tract. These studies are necessary (1) to determine if the level of nutrients and other contaminants is rising (i.e., baseline data), (2) to provide data for modeling effors and (3) to explain the mortality of certain benthic organisms such as corals and seagrass.

The strategy of this study is to install seepage meters and measure (quarterly) the volume of groundwater seepage into the overlying marine environment. The waters will be analyzed for major nutrient levels. The primary product will be a set of volume values which can be used by hydraulic modelers to determine the source and movement of Florida Bay waters. Submarine groundwater input into Florida Bay has been ignored by modelers and results show current models are likely to be erroneous. An additional major product will be an improved seepage meter design.



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Script last updated: 23 October 2018 @ 12:03 PM by THF. Record creator: BJM. Record last updated by: BJM.