ARTESIAN WELL

ARTESIAN WELL. Groundwater in aquifers between layers of poorly permeable rock, such as clay or shale, may be confined under pressure. If such a confined aquifer is tapped by a well, water will rise above the top of the aquifer and may even flow from the well onto the land surface. Water confined in this way is said to be under artesian pressure. The aquifer is called an artesian aquifer.

Deep wells drilled into rock to pass through the water table and reach far below it are often called artesian wells in ordinary conversation, but this is not necessarily a correct use of the term. Such deep wells may be just like ordinary, shallower wells; great depth alone does not automatically make them artesian wells. The word artesian, properly used, refers to situations where the water is confined under pressure below layers of relatively impermeable rock.

Artesian wells can be sometimes flow to the land surface naturally because of underground pressure.

Generally, the upper layer of an aquifer system is the unconfined aquifer, which does not have a confining layer of solid material above it. The top altitude of this aquifer is called the "water table", below which the ground and rock has all the spaces and voids full of water. Water from this aquifer must be pumped out in a well to get to the land surface.

In some locations confined aquifers can exist below the unconfined aquifers. These confined aquifers have layers of solid material above and below them and are under pressure from the rock weight. For water to recharge these aquifers, it must seep down from the surface at a distance away and travel somewhat horizontally into the confined aquifer. Wells that tap these confined aquifers are "artesian wells". The pressure that the pressurized aquifer pushes water up to is the "piezometric level". If this level is below the land surface altitude (the right side artesian well in the diagram) the water will not shoot out of the well at the land surface...the well is called an artesian well. If the piezometric level is higher than the well head altitude at the land surface (the artesian well on the left-side of the diagram), the water will be pushed upward in the well and emerge at the land surface, with no pump needed. This kind of well is a flowing artesian well. (1)

Dubuque has a long history of artesian wells. DUBUQUE BREWING AND MALTING COMPANY filled its water needs from an artesian well on its premises. In November, 1885 arrangements were made to supply the water tank of the CHICAGO, MILWAUKEE, AND ST. PAUL RAILROAD from the company's artesian well. Artesian well water was heated to 80 degrees for use by the DUBUQUE NATATORIUM. In 1916 in a unique chapter in Dubuque history, the JULIEN HOTEL offered the people of Dubuque artesian well water from a well in the empty lot at the rear of their building. The taste of the local water was poor. The hotel stated the well was over 3,000 feet deep and the water "absolutely pure."

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Source:

1. "Artesian Water and Artesian Wells," United States Geological Service, Online: https://www.usgs.gov/special-topic/water-science-school/science/artesian-water-and-artesian-wells?qt-science_center_objects=0#qt-science_center_objects