Water Quality 102: Groundwater
By: Bryan Duggan
Water and Environmental Specialist
The abundance of water and its unique interaction with the landscape is one of the
essential physical properties of this planet that enables life to flourish. Often when we
think of water we picture in our minds beautiful lakes, or clear bubbling streams;
however; just as important is the water that comes from the ground; groundwater.
Groundwater comes from rain, snow, sleet, and hail that soaks into the ground. The water
moves down into the ground because of gravity, passing between particles of soil, sand,
gravel, or rock until it reaches a depth where the ground is filled, or saturated, with water.
Acting like a huge sponge the earth holds all that water stored in the ground, and
depending on geological deposits and topography the water can flow through soil
substrates and rock formations to eventually connect with surface waters, thus completing
a portion of the water cycle.
As a portion of the earth’s hydrology, groundwater is significant; according to the online
encyclopedia Wikipedia: “groundwater makes up about twenty percent of the world's
fresh water supply, which is about 0.61% of the entire world's water, including oceans
and permanent ice. Global groundwater storage is roughly equal to the total amount of
freshwater stored in the snow and ice pack, including the north and south poles.” This
makes it an important resource which can act as a natural storage that can buffer against
shortages of surface water, as in during times of drought.
Naturally there are different zones of saturation under ground and depending upon the
nature of the substrate will define the extent and depth of the groundwater hydrology.
The area that is filled with water is called the saturation zone and the top of this zone is
called the water table. Depending on local geology, the water table may be very near the
ground’s surface or it may be hundreds of feet below. Often we can see where the water
table intersects with surface water as it flows from rocks, forming lakes, rivers, or
springs.
Most groundwater is clean, but groundwater can become polluted, or contaminated. It can
become contaminated from leaky underground fuel tanks, septic systems, industrial
spills, or even excessive and frequent pesticide and fertilizer use by homeowners.
Because of the underground nature of groundwater (depth) clean up can be expensive and
is often avoided by relocating wells.
The public drinking water supply for the North Bend Coos Bay community is
predominately supplied by the Pony Creek/Joe Ney Reservoirs; however; many other
Coos County residents depend upon private wells to obtain their drinking water. Wells
can be drilled into aquifers, and water can be pumped out. Aquifers are natural
underground layers of porous rock that store water. Precipitation will eventually
replenish the water in an aquifer. However, you must remember that infiltration is a very
slow process. If water is pumped out of an aquifer faster than new water comes into the
aquifer, the aquifer could run dry.
Part of the Tribe’s Water Quality Monitoring Program is to monitor the Reservation’s
groundwater levels. Tribal Land Resource and Environmental Service’s staff are
interested in protecting the groundwater underneath the Reservation as a potential source
of drinking water and also to monitor for future changes as water needs and cycles shift.
With careful use and by reducing sources of pollution, ground water can continue to be
an important natural resource in the future. Be mind of what you discard into the ground,
for pollutants have a persistent ability to infiltrate surface and groundwater systems
threatening all of our health and natural resource wealth.