Groundwater monitoring wells are principally used for observing groundwater levels and flow conditions, obtaining samples for determining groundwater quality, and for evaluating hydraulic properties of water-bearing strata. 

The quality of water intercepted by a monitoring well can range from drinking water to highly polluted water. 

Monitoring wells, along with other types of wells, can provide a pathway for the movement of poor-quality water, pollutants, and contaminants. Because monitoring wells are often purposely located in areas affected by pollutants and contaminants, they pose an especially significant threat to groundwater quality if they are not properly constructed, altered, maintained, and destroyed. 

The California Legislature amended the California Water Code in 1986 specifically to include requirements for monitoring well standards. 

Well drillers must obtain Environmental Health approval and a permit issued by the Sierra County Building Department prior to drilling a monitoring well.