DEFINING SHALLOW GROUNDWATER DYNAMICS ALONG THE WHITE RIVER IN MANISTEE NATIONAL FOREST, MICHIGAN: PREPARING FOR POTENTIAL ECOSYSTEM CHANGE IN CRITICAL STREAM HABITATS

Threats to ground water in Michigan have taken center stage in public and regulatory arenas in recent years. Brought about in large part by public concerns over extraction of ground water by the bottled water industry, new legislation and regulatory tools have been developed to assist in statewide water resources management. Forest resource managers in the Huron-Manistee National Forests in Michigan seek to protect and manage groundwater dependent ecosystems and shallow water resources in the face of development threats and impending climate change. Four Michigan State Natural Rivers including the Manistee, Pere Marquette, Pine, and White lie within Manistee National Forest. The Manistee, Pere Marquette, and Pine are also designated as National Wild and Scenic Rivers. These and other rivers form critically important trout and salmon fisheries and recreational resources for the state and nation. Moreover, these streams are intimately connected to shallow groundwater and depend on low-gradient groundwater discharge, particularly in headwater reaches, for streamflow. The objectives of this work are to help develop an understanding of the physical system along a headwater reach of the White River within Manistee National Forest in Newaygo County, Michigan, and identify the role of groundwater in maintaining this fisheries resource. A network of shallow piezometers was installed along an upland-wetland transition to monitor groundwater discharge to the riparian system and permit measurement of site-specific hydrological parameters. The network was designed to 1) provide forest resource managers with an understanding of current hydrologic conditions in this riparian environment, 2) describe the role of groundwater in streamflow maintenance, 3) make site-specific data available for existing statewide databases used in regulation and planning, and 4) be expanded in the future. Measured head changes and hydraulic gradients suggest seasonal and event-based variability in hydrologic regimes of this upland - wetland - stream system. Site-specific hydraulic conductivity data can refine existing data in regional databases used for the state of Michigan's regulatory Water Withdrawal Assessment Tool.