Ground-water-withdrawal component of the Michigan water-withdrawal screening tool

A water-withdrawal assessment process and Internet-based screening tool have been developed to evaluate proposed new or increased high-capacity water withdrawals in Michigan. Michigan legislation defines high capacity withdrawals as those capable of removing an average of 100,000 gallons per day for a consecutive 30-day period. This report describes the ground-water component of the screening tool, provides background information used to develop the screening tool, and documents how this component of the screening tool is implemented. The screening tool is based on application of an analytical model to estimate streamflow depletion by a proposed pumping well. The screening tool is designed to evaluate intermittent pumping, to account for the dynamics of stream-aquifer interaction, and to apportion streamflow depletion among neighboring streams. The tool is to be used for an initial screening of a proposed new or increased high-capacity withdrawal in order to identify withdrawals that may cause adverse resource impacts. The screening tool is not intended to be a site-specific design tool. Results of an example application of the screening tool in Kalamazoo County, Mich., are compared to streamflow depletion estimated by use of a regional ground-water-flow model to demonstrate its performance.