OFR 07-02; Geology in support of ground-water management for the Twin Cities Metropolitan Area, Metropolitan Council Water Supply Master Plan Development - Phase I

Abstract

This report summarizes work by the Minnesota Geological Survey to provide the Metropolitan Council, as part of their Phase I Water Supply Master Plan, with information to help characterize recharge to metropolitan area bedrock aquifers. The Council requested a better understanding of the surface and subsurface distribution of unconsolidated deposits overlying bedrock, with the goal of identifying preferential water pathways from the land surface to bedrock. To this end, the Minnesota Geological Survey provided: 1.) a seamless surficial geology map of the greater Twin Cities metropolitan area; 2.) a collection of historic metro-wide water chemistry data used to prioritize areas for subsurface mapping – 27 new samples were collected in northwestern Hennepin County where data was sparse; and 3.) a three dimensional model of unconsolidated deposits from the land surface to bedrock for the northwest metropolitan area, hereafter referred to as the geologic framework model.