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Groundwater resources in Marshall County are abundant, with fair to good water quality. All areas of the county have the ability to produce enough water for domestic needs from drilled wells at reasonable depths. Multiple zones of production are common throughout the county. The depth to uppermost production is between 30 and 150 feet. A few wells obtain shallow perched water from gravel or alluvial deposits, but these zones often will not yield enough water for an adequate domestic supply during periods of low rainfall, which is common in late summer and fall. In general, the chemical quality of the water is good, but water from some aquifers contains objectionable amounts of iron and manganese. Water from alluvium and limestone is generally hard to very hard, with moderate to high levels of dissolved solids. Some limestone wells in the eastern part of the county have minor amounts of hydrogen sulfide. Water from the unconsolidated sand or gravel aquifers is considered soft and slightly acidic, with low dissolved solids. Water quality generally is good, except in areas where percolation of surface water and fluids from domestic sewage-disposal systems, and other sources of domestic or industrial pollution, have contaminated the aquifer. In a few wells, harmful amounts of nitrate have been detected. Groundwater sometimes contains naturally occurring iron in objectionable amounts from the deeper zones. In some formations with slightly acidic groundwater, a chemical reaction between the acidic groundwater and steel well casing and pump equipment will produce a high iron content in the water. |
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