Ground Water Studies
Ground-water quality was assessed for aquifer/land use combinations using three sampling strategies: (1) regional studies of selected major aquifers (subunit surveys), (2) targeted-area studies in selected land-use areas (land-use studies), and (3) a localized study of processes occurring along shallow ground-water flow paths (flow-path study). These studies and surveys emphasize shallow ground water, the quality of which is likely influenced by overlying land use and land cover. Stratification for ground-water sampling was based on the spatial distribution of shallow surficial, buried sand and gravel, and bedrock aquifers. As with the stratification of surface water, the first level of stratification was the glacial deposit composition, followed by the type of surficial geology (till or outwash).
Within the areas delineated by stratification, an additional level was added to differentiate among aquifers. For each aquifer, general land use and land cover were also used as a basis for the study design for the ground-water component. Investigation of potential contamination of aquifers by nutrients, pesticides, and VOCs was the primary objective of the land-use studies and subunit surveys. The flow-path study was intended to assess changes in ground-water chemistry along a ground-water flow path.
Ground-water investigations are divided into 3 types:
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U.S. Department of the Interior |
U.S. Geological Survey
