David P. Lusch , Ph.D. Distinguished Senior Research Specialist Michigan State University

1. Michigan’s Water Withdrawal Assessment Process and Using the WWA Tool for Planning and Watershed Management David P. Lusch, Ph.D. DistinguishedSenior Research Specialist Michigan State University Dept. of Geography,Remote Sensing & GIS Research and Outreach Services Group Institute of Water Research and

2. Michigan’s Water Withdrawal Assessment Process for Planning and Watershed Management • The Great Lakes Compact: why Michigan is regulating large-quantity water withdrawals • Brief review of Michigan Water Law • Tutorial on some key hydrologic terms and concepts

3. Michigan’s Water Withdrawal Assessment Process for Planning and Watershed Management • Sources of Water in Rivers • Overland Flow • Baseflow (i.e., groundwater discharge) • Interflow • Direct precipitation in channel

4. Michigan’s Water Withdrawal Assessment Process for Planning and Watershed Management ET Overland Flow (runoff) Soil Moisture Precipitation Infiltration Water table Interflow Groundwater Groundwater flow path • Sources of Water in Rivers

5. Michigan’s Water Withdrawal Assessment Process for Planning and Watershed Management • Baseflow of a river • the amount of groundwater that discharges from an aquifer into the watercourse. • Baseflow occurs year-round, but fluctuates seasonally depending on the level of the water-table aquifer. • The baseflow of a river is supplemented by direct runoff during and immediately after precipitation or snowmelt events.

6. Michigan’s Water Withdrawal Assessment Process for Planning and Watershed Management Runoff dominated river – very little baseflow: “flashy” and warm Intermediate river – baseflow + runoff: warm/cool, but fewer extremes Baseflow dominated river – very little runoff – cold/cold transitional

7. Michigan’s Water Withdrawal Assessment Process for Planning and Watershed Management • Index Flow • the flow that is met or exceeded 50% of the time for the lowest summer flow month of the flow regime, determined over the period of record or extrapolated from USGS flow gauges in Michigan.

8. Michigan’s Water Withdrawal Assessment Process for Planning and Watershed Management • Groundwater Withdrawal Impacts on Rivers • Reduced flow • Altered water temperatures

9. Michigan’s Water Withdrawal Assessment Process for Planning and Watershed Management ET Runoff -WARM Soil Moisture Precipitation Water table Interflow Groundwater Groundwater Flow - COLD Reduced Baseflow • GW Withdrawal Impacts on Rivers

10. Michigan’s Water Withdrawal Assessment Process for Planning and Watershed Management • Pumping well water sources • Initially, water is removed from storage in the aquifer, and the head near the well is reduced inducing flow towards the well. • As water is removed from storage, a cone of depression forms around the well.

11. Michigan’s Water Withdrawal Assessment Process for Planning and Watershed Management • Pumping well water sources • In most cases, the cone of depression continues to expand until the pumpage is balanced by adecreasein dischargefrom the system, resulting from the lowered head in the system which decreases the flow gradient in discharge areas and may shift the groundwater divide. • The change in discharge due to pumping is called “capture.”

12. Michigan’s Water Withdrawal Assessment Process for Planning and Watershed Management • Source of water to a pumping well • Decrease in the dischargefrom the system, resulting from the lowered head in the system, decreased gradients in discharge areas and shifts in the groundwater divide. Ground-water divide gaining stream Cone of depression stream gains less Q2 > Q1 Ground-water divide losing stream

13. Michigan’s Water Withdrawal Assessment Process for Planning and Watershed Management • Source of water to a pumping well

14. Michigan’s Water Withdrawal Assessment Process for Planning and Watershed Management • The next segment • Water Withdrawal Tool Science