What is a characteristic of an artesian well?

An artesian well is defined by its ability to allow water to flow freely to the surface without the need for mechanical pumping. This phenomenon occurs because the water in an artesian aquifer is under pressure, typically due to a confining layer above it that traps the water within a porous rock layer. When a well is drilled into this aquifer, the pressure can cause the water to rise naturally, often resulting in a situation where water flows out of the well on its own. This characteristic sets artesian wells apart from non-artesian wells, which do require pumps to bring water to the surface.

The other options do not accurately describe the nature of artesian wells. For example, artesian wells specifically do not require pumping, as they utilize the natural pressure of the groundwater. They are also found in regions where groundwater exists at sufficient levels, indicating that while they may not always be near rivers, they are not typically in low groundwater areas. Lastly, while artesian wells can be located near rivers, this is not a defining feature, as their presence is more related to the geological and hydrological conditions of the area rather than proximity to surface water bodies.