Project Summary Sheet

Project: Ground Water-Surface Water Interactions and Relation to Water Quality in the Everglades

Web Sites: http://sofia.usgs.gov/projects/wtr_flux/; http://sofia.usgs.gov/sfrsf/entdisplays/waterlevels/; http://sofia.usgs.gov/exchange/harvey/harveyDATA.html

Location (Subregions & Counties): Central Everglades; Palm Beach, Broward and Miami-Dade Counties

Funding (Source): USGS Place-Based Studies Program, SFWMD (Steve Krupa, skrupa@sfwmd.gov)

Principal Investigator(s): Judson Harvey (jwharvey@usgs.gov, 703.648.5876)

Project Personnel: Jim Krest (jmkrest@usgs.gov, 703.648.5472); Jessica Thomas (jlthomas@usgs.gov, 703.648.5473)

Supporting Organizations: USGS, SFWMD, NPS/Everglades National Park

Associated / Linked Projects: Tides and Inflows at the Mangrove Ecotone (TIME) http://time.er.usgs.gov/; Integrated Geochemical Studies in the Everglades http://sofia.usgs.gov/projects/wetland_seds/; http://sofia.usgs.gov/projects/evergl_merc/; Freshwater Flows into Florida Bay http://sflwww.er.usgs.gov/projects/freshwtr_flow/

Overview & Status: The primary objective of this project is to quantify hydrologic fluxes between ground water, peat porewater, and surface water, and to determine the effects that those fluxes have on movement and fate of contaminants in the Everglades. The principal research sites are the Everglades Nutrient Removal Project (ENR), Water Conservation Area 2A (WCA-2A), and the freshwater wetlands of Everglades National Park. Ground-water recharge and discharge are being quantified, along with fluxes across the peat and aquifer layers of important dissolved constituents such as mercury, sulfate, chloride, and nutrients. Sources of surface water and ground water, mixing of those source waters, and travel times through surface and subsurface flow paths also being quantified using geochemical and isotopic tracers. The research relates surface-water and ground-water interactions to geologic and environmental processes, and contrasts pre-drainage scenarios with present-day conditions that have been affected by water-resources management.

Needs & Products: A key measure of success in the Everglades restoration is protecting water quality from unintended degradation that could result from new management strategies and changing hydrologic conditions. Our work is revealing how past management of water-resources has increased interactions between wetland surface water and ground water, and how those increased interactions affected water quality in peat pore water and in the thin layer of fresh ground water that underlies the Everglades. Field-oriented research and modeling is determining (1) magnitude of interactions between groundwater, peat porewater, and surface water and associated solute fluxes, (2) factors related to water-resources management that are responsible for increasing those interactions, (3) the extent to which the vulnerable fresh water lens near the top of the aquifer is being affected by recharge of contaminated surface water and discharge of ground water with high salinity from lower in the aquifer, and (4) the timescale over which contaminants stored in peat and groundwater will be returned to the surface water system. Products include journal publications, USGS Water-Resources Investigations reports, SFWMD cooperative agreement reports, online versions of reports posted on SOFIA web site, and verbal reporting at national scientific meetings and local briefings in south Florida.

Application to Everglades Restoration: Successful restoration of the Everglades requires comprehensive knowledge of ground-water recharge and discharge and solute fluxes between surface water, peat pore water, and the underlying aquifer. Few reliable estimates are currently available for recharge and discharge. There is a similar lack of information about rates of solute exchange between peat porewater and Everglades surface water. This gap not only leaves the surface water budget uncertain, but also hampers progress understanding the mobility and fate of contaminants in response to further modifications of the hydrology under restoration. The present project addresses those needs by quantifying recharge and discharge and movement and fate of contaminants in the Everglades, and identifying the relative importance of controlling factors, including the role of water-resources management. In addition to developing initial estimates of recharge or discharge, and accompanying solute fluxes, our data are being used to verify some of the more important hydrology and water-quality models guiding the restoration, including TIME (USGS-Langevin, Swain, and Schaffranek), SFWMM (SFWMD-Obeysekera), ENRP Nutrient Balance (SFWMD-Chimney), and STA Design Reassessment (SFWMD-Kadlec/Walker and DB Associates)