4 research outputs found
Saline water intrusion from deep artesian sources in McGregor Isles area of Lee County, Florida
Upward leakage of saline water from an artesian aquifer below 1,500 feet
has caused an increase in chloride concentration in the lower Hawthorn aquifer
from less than 1,000 mg/1 (milligrams per liter) to values ranging from about
1,300 to 15,000 mg/1. Similarly the higher temperatures of the intruding water
has caused an increase in water temperatures in the aquifer from 82"F to values
ranging from 83 to 93"F. The intruding water moves upward either through the
open bore hole of deep wells or test holes, or along a fault or fracture system,
which has been identified in the area. From these points of entry into the lower
Hawthorn aquifer, the saline water spreads laterally toward the south and
southeast, but is generally confined to components of the fault system.
The saline water moves upward from the lower Hawthorn aquifer into the
upper Hawthorn aquifer through the open bore hole of wells, which connect the
aquifers. This movement has resulted in an increase in chloride from less than
200 mg/1 in the unaffected parts of the upper Hawthorn aquifer to values
commonly ranging from about 300 to more than 3,000 mg/1 in parts of the
aquifer affected by upward leakage. The upper Hawthorn aquifer is the principal
source of ground-water supply for public water-supply systems in western Lee
County.
Similar effects have been noted in the water-table aquifer, where chloride
increased from less than 100 to concentrations ranging from about 500 to more
than 5,000 mg/1. This was caused by the downward infiltration of water
discharged at land surface from wells tapping the lower Hawthorn aquifer.
The spread of saline water throughout most of the McGregor Isles area is
continuing as of 1971.
(40 page document