INTRODUCTION This report describes the history of roads through the Lower Glades of Everglades National Park, Florida and their influence on salinity intrusion. The chronology that lead to this work is interesting. The U.S. Geological Survey flew a series of helicopter electromagnetic surveys over portions of Everglades National Park to map saltwater intrusion starting in 1994 (Fitterman et al., 1995; Fitterman, 1996; Fitterman and Deszcz-Pan, 1998, 2002). These surveys identified variations in the electrical resistivity that were associated with changes in ground-water quality. The patterns of ground-water quality have been traced to natural saltwater intrusion, such as the effect of tidal rivers on lowering hydrologic heads far inland, and the influence of man-made structures, such as canals and roadways on surface water flow. These latter effects are of interest as they represent variations from the natural state of affairs in the park. Previous investigations had been done by Everglades National Park staff on the influence of some roads and canals on the near surface hydrology. This information was scattered through a number of National Park Service publications. In an effort to bring these materials together in an easily located reference, along with new data on flows through culverts beneath the main park road, this report was written.

Introduction Ingraham Hwy & Homestead Canal Construction Culverts Airborne Resistivity Tables References PDF Version

Figure 1: Location of S.R. 9336 in Everglades National Park. [larger image]

Introduction

The main road in Everglades National Park (ENP) connects Flamingo with the Park's entrance and continues onto the coastal ridge of Dade County (Fig. 1). The current alignment of the road, an extension of State Road 9336, formerly known as State Road 27, was built in 1956 when a portion of what was then known as Ingraham Highway was replaced with a more northward section. The road has been the subject of some controversy. Some scientists have claimed that the roadbed is a barrier to natural flow to Florida Bay, while others have blocked culverts to hold fresh water back in the wetlands east of the road and north of Florida Bay. The South Florida Natural Resources Center is conducting a study to assess the current condition of the culverts and to determine the patterns of water flow in the area adjacent to the road. Information has been gathered on the road's history, the historical water levels and flow patterns. Monitoring sites have been installed to record water level, salinity and flow, which are being measured during times when water is present. In addition to the Park project, a complementary project has been undertaken by the United States Geological Survey (USGS). The USGS has been conducting investigations in the southern Everglades to assess the extent of saline-water intrusion by means of airborne electromagnetic geophysical measurements. This report condenses the information gathered to date.

Related information:

SOFIA Project: Geophysical Studies of the Southwest Florida Coast