- Freshwater Sustainability
This working group focuses on the vulnerability of freshwater resources and water quality to sea-level rise and urban development. The quality of water in South Florida ecosystems has significantly declined over the last century (Science Subgroup, 1996). Changes of land usage for agriculture, water management to provide irrigation and flood control, coupled with accelerated urban development near the coastline have introduced ecosystem scale problems that potentially jeopardize the sustainability of valuable resources including the Reef Track along Southeast Florida, Florida Bay, Everglades National Park, Biscayne Bay and the Florida Keys. Excess phosphorus, mercury, and other contaminants harmed the region’s surface water and groundwater so that intervention was deemed necessary to restore these ecosystems and to guarantee their preservation. The Comprehensive Everglades Restoration Plan (CERP) approved by Congress in 2000 notes that the Everglades, Florida Bay, Biscayne Bay and the Florida Keys are very complex ecosystems and the connections between them are not fully understood by scientists (US ACOE, 1999). CERP’s goal is to increase regional water supplies and restore the hydrological paths in the Everglades to pre-1900 conditions. The resulting increase in fresh water supply would help stem the tide against aquifer salinization induced by sea level rise.
Despite an adequate supply of rainfall (160 cm/yr), the freshwater supply of the Biscayne Aquifer is currently strained by numerous competing socio-ecological interactions. The United States Environmental Protection Agency (USEPA) designated the Biscayne Aquifer as a “Sole Source Aquifer” for the inhabitants of Miami-Dade and Broward, Palm Beach and Monroe Counties. Miami-Dade County estimates a population of 2.7M by year 2027. Per capita water consumption is targeted to be 148 gallons per capita day, which will create a demand of an estimated 418 mgd by year 2027. Furthermore it is located within the Greater Everglades watershed, and is a critical source of fresh water for the CERP. Water quality in the Biscayne Aquifer is excellent, but has been affected by seawater intrusion since the 1940s (Parker et al, 1955; Schroeder et al., 1958). The extent of seawater intrusion is curtailed somewhat by water control structures along the canals that discharge to the ocean (Leach et al., 1972; Sonenshein, 1997). However, in 2008 the USGS released a provisional seawater intrusion map that indicates landward migration in the last few years (Figure 1). The cause for this recent increase in unknown, but may be related to population growth, altered water management water delivery guidelines, or climate change/sea-level rise. Sea-level rise as measured at Key West, Fl has increased about 2.5 mm/yr in the last 100 years. Current monitoring of water levels at the water control structures in Miami-Dade County indicates a similar increase over the past 20 years.