Great Lakes Basin Pilot

Description of Study At the request of Congress, the U.S. Geological Survey (USGS) is assessing the availability and use of the Nation’s water resources to gain a clearer understanding of the status of our water resources and the land-use, water-use, and natural climatic trends that affect them. The goal of the National Assessment of Water Availability and Use Program is to improve our ability to forecast water availability for future economic and environmental uses. Simply put, the assessment will help characterize how much water we have now, how water availability is changing, and how much water we can expect to have in the future. Water availability is a function of many factors, including the quantity and quality of water and the laws, regulations, economics, and environmental factors that control its use. The focus of the Great Lakes Basin study is on improving fundamental knowledge of the water balance of the basin, including the flows, storage, and water use by humans. An improved quantitative understanding of the basin’s water balance not only provides key information about water quantity but also is a fundamental basis for many analyses of water quality and ecosystem health.

Location of the Great Lakes Basin in the United States and Canada. Click on the image to view a larger version.

Products to Date

	Consumptive Water–Use Coefficients for the Great Lakes Basin and Climatically Similar Areas		Fact Sheet: Consumptive Water Use in the Great Lakes Basin
	Estimate of Ground Water in Storage in the Great Lakes Basin, United States, 2006		Estimation of Shallow Ground-Water Recharge in the Great Lakes Basin
	Historical Changes in Precipitation and Streamflow in the U.S. Great Lakes Basin, 1915–2004		Compilation of Regional Ground-Water Divides for Principal Aquifers Corresponding to the Great Lakes Basin, United States
	Lake-Level Variability and WaterAvailability in the Great Lakes		Great Lakes Basin Water Availability and Use -- A Study of the National Assessment of Water Availability and Use Program

Approach

An understanding of water availability in an area requires more than information regarding the amount of water in a system. Water managers need to understand how the system changes in time and how it reacts to changes in environmental conditions and use. Constraints on use including current off-stream use, in-stream requirements, and water quality limitations also must be recognized. The Great Lakes Basin Pilot focuses on developing the understanding of the dynamics of the water resources in the basin in terms of the flows and storage of water in both ground and surface water. The Pilot also seeks to illustrate the importance of water-use data to quantifying water availability. Other constraints including water quality and in-stream flow requirements are subjects of other USGS programs.

Surface-Water Flows and Storage

The major tasks include:

• Development of techniques to estimate flow in ungaged basins,
• Development of techniques to deliver real-time estimates of surface-water flows for the U.S. side of the Great Lakes Basin,
• Analysis of trends in streamflow and precipitation using data collected over the past 90 years (see Historical Changes in Precipitation and Streamflow in the U.S. Great Lakes Basin, 1915–2004),
• Exposition of the changes in Great Lake water levels over the past 4500 years and the relation to water availability (see Lake-Level Variability and Water Availability in the Great Lakes).

Ground-Water Flows and Storage

The major tasks include:

• Description of ground-water divides for aquifers on the U.S. side of the Great Lakes Basin including discussion of the changes in these divides in response to pumping and the uncertainty in the location of these divides for much of the region (see Compilation of Regional Ground-Water Divides for Principal Aquifers Corresponding to the Great Lakes Basin, United States).
• Estimates of recharge to ground water. Initial estimates are presented in Estimation of Shallow Ground-Water Recharge in the Great Lakes Basin. Current work includes estimates of the changes in recharge with time, increased spatial resolution of recharge estimates, and development of techniques to project recharge under changing climatic conditions.
• Estimation of the amount of potable ground water in storage in the aquifer systems on the U.S. side of the Great Lakes Basin (see Estimate of Ground Water in Storage in the Great Lakes Basin, United States, 2006).
• Development of a ground-water-flow model for the contributing area to Lake Michigan to analyze and illustrate the source of water to wells and the dynamics of the ground-water system.

Water-Use Analysis

The major tasks include:

• Compile consumptive-use coefficients by water-use categories for the Great Lakes Basin and climatically similar areas.  This compilation is in a report that includes:
  • consumptive-use coefficients by water-use categories;
  • a selected statistical analysis;
  • summary tables by geographical area and water-use category;
  • an annotated bibliography of references with consumptive-use coefficients; and
  • an appendix with detailed consumptive-use coefficient tables from selected references
  for the Great Lakes Basin and areas climatically similar to the Great Lakes Basin, and selected references for elsewhere in the world.
• Analysis of return flow and water use data in Ohio and water-use data in Indiana, and Wisconsin for consumptive-use coefficients and monthly variability of water use and consumptive use.  This analysis will be compared to consumptive-use coefficient statistics found by Shaffer and Runkle (2007) for water-use categories.
• Compilation and publication of water-use data and estimates for the U.S. side of the Great Lake Basin water use by Hydrologic Unit Code for 2005.

For additional information, please contact:

Howard W. Reeves, Project Chief
U.S. Geological Survey
Michigan Water Science Center
6520 Mercantile Way, Suite 5
Lansing, Michigan 48911
Telephone: (517) 887-8914
Fax: (517) 887-8937
Email: hwreeves@usgs.gov

Related Information on Water Availability:

	Concepts for National Assessment of Water Availability and Use: This report describes the scope and magnitude of efforts needed to provide periodic assessments of the status and trends in availability and use of fresh-water resource.		Water Budgets: Foundations for Effective Water-Resources and Environmental Management: Water budgets provide a means for evaluating availability and sustainability of a water supply.
	Facing Tomorrow's Challenges -- U.S. Geological Survey Science in the Decade 2007-2017: One of six priority science directions for the USGS is “A Water Census of the United States.”		A Strategy for Federal Science and Technology to Support Water Availability and Quality in the United States: One of seven strategic elements to address water challenges facing the Nation is to “Implement a National Water Census.”