BACKGROUND
Ground water supplies are usually used only by smaller communities because of the limited quantity of water that can be obtained from an aquifer.

Ground waters generally:
a) have water that may be excessively hard., due to the percolation of the water through mineral deposits.
b) require a minimum degree of treatment
c) have a water quality that is usually very stable in temperature, and constituents.

Ground Water Sources
more groundwater than all natural and artificial reservoir storage, including the Great Lakes
Ground water sources are:
a) wells
b) infiltration galleries: The interception of water moving to streams
c) springs

AQUIFER: Water bearing layer or formation (stratum)
a) unconfined aquifer, it is called a "free surface well," "gravity well" or "water table well." An unconfined aquifer is one which contains water with a free surface at atmospheric pressure.
b) confined aquifer, where both above and below the draw off point the water is isolated, and contains water under pressure, it is called an "artesian well" and the aquifer is known as an artesian aquifer. Free surface wells tend to be shallow and the artesian wells deep.
c) Changes in stream flow, evapotranspiration rates, atmospheric changes, winds, tides, withdrawal rates of the water from the aquifer, all impact the groundwater level. The impact is further defined by the aquifer type: free or confined.

Water that can be drained by gravity is the "specific yield". The void or poor size, shape of the soil particles in void spaces, the distribution of the poorer shape and size, and agree of the compaction of soil are factors which will impact this.

WELL HEAD PROTECTION PROGRAM
In 1974 the Safe Drinking Water Act established the wellhead protection program for the entire country by having two programs designed to establish this protection. (sole source aquifers and underground injection control program).

In 1986 the Safe Drinking Water Amendments established a third program, wellhead protection program for the entire country. It requires each state to develop and manage a program to "protect wellhead areas within their jurisdiction from contaminants which may have any adverse affects on the health of persons." The wellhead protection area is defined as "the surface and subsurface area surrounding a water well or wellfield, supplying a public water system, through which contaminants are reasonably likely to move toward and reach such water well or wellfield." Protection therefore requires the prevention of a pollution source from contaminating the well and its aquifer source.

There are six specific areas that must be addressed:
a) The specific duties and responsibilities of the state and local agencies.
b) Define the wellhead protection area.
c) Describe the protective procedures to be followed for contaminants within the prescribed areas.
d) Procedures for surveys and determinations for contaminants within the prescribed wellhead protection areas.
e) Procedures for surveys and determinations for contaminants within all future wellhead protection areas.
f) Procedures for the establishment of contingency plans for alternative sources of water for contaminated well sites and aquifers.

Other Operational Considerations:
Most all wells are now equipped with a disinfection capability such as chlorination, and many have also added fluoridation as a process. The water is chlorinated to insure a disinfection residual for the prevention of a re-growth condition, and as a health preventative situation (to guard against cross-connections, etc) within the distribution system. The photograph at the left shows a yellow, color-coded, chlorination feed line.

Groundwater Recharge
This is naturally occurring, at a very slow rate. "Mother nature" is not prepared to support the amount of groundwater being extracted at today's high rate. Mother nature could use a little help, several areas of the country have undertaken the task of reversing this trend by injecting clean freshwater into their aquifers. Over 700 MGD (means 700 Million Gallons per Day) in just California alone, is injected into the groundwater.

There are a few methods to do this:
1) holding basins- where the water percolates into the ground, and
2) modified stream bed - the streambed is cut, widened, scarified, and also
3) injection wells - water should be clear, little or no sodium, and be chlorinated (or some form of disinfection). There have been problems with bacteria, air binding, and siltation at the screens, and steps taken to address these problems are in order.

Saltwater intrusion: usually freshwater floats on top of the surface of the " heavier" saltwater. An example is a town near some highly saline water sources like the ocean. The town pumps the freshwater out of the ground, and salty seawater moves in under the town to replace the removed freshwater. (Sea water has a specific gravity of 1.025). A 1 ft. decrease in freshwater rises the saltwater approximately 40 feet in the water table. Recharging coastal areas with freshwater has been undertaken to produce this " head" such as in Southern California. Long Island over pumped its groundwater supplies over many years, and sent its storm water runoff straight to the ocean. It now transports water in from upper New York State, as its groundwater is now too salty for potable water consumption.

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