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How to Track Salt Water Underground

Salt water can only flow underground where there is a place for it to flow. A logical place for it to flow along sea coasts is into freshwater aquifers. An aquifer is a pool or river of fresh water underground; most wells are drilled into aquifers. Salt water can also intrude into freshwater aquifers as a result of road salting. Salt from roads and from road-salt storage can slowly creep into the water table and flow from there into an aquifer or other well sources.

Things You'll Need

Salt testers
Universal Transverse Mercator translator (in some cases)
USGS maps
USGS "Ground Water Atlas of the United States"

Instructions

- 1
  Collect samples from all public water supply wells in the area you are investigating. Test the samples with a ̶0;salt tester.̶1; Salt testers are hand-held devices that measure the concentration of salt in water in parts per million.
- 2
  Map the location of each well using the standard Universal Transverse Mercator (UTM) geographic coordinate system used by the United States Geological Survey (USGS). Numerous tools are available online to translate other coordinate systems, including Global Positioning Satellite coordinates to UTM coordinates. You don̵7;t need a translator if you map the well locations directly on a USGS map.
- 3
  Mark the location of the wells on a USGS map that covers the area you are investigating.
- 4
  Map the location of the aquifer under the wells on the same USGS map, using the USGS "Ground Water Atlas of the United States."
- 5
  Diagram or otherwise record the concentrations of salt at all well points over the aquifer you investigate.
- 6
  Collect additional samples from all wells and retest those samples with a salt tester at regular intervals. Any increase in salt levels indicates salt water incursion.
- 7
  Track salt water incursion by comparing salt levels in adjoining and widely separated wells.

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