An Innovative Approach to Assess Water Resources

Introducing Virtual Water Accounting to the Great Lakes

Download PDF – March, 2015

What is Virtual Water Accounting?

Virtual Water Accounting is a method of assessing the true impact of water extraction on local water resources and ecosystem services. The approach provides a framework to account for the “Virtual Water”; water that is embedded in products during the production of goods for export (primarily through evaporative consumption) and is lost to the watershed: in this case, the Great Lakes Basin.

Virtual Water as concept requires that we “see” or consider all of the water that is being used in the production and export of that product as well as throughout the life of that product or service. For example, it takes about 900 liters of water to produce 1 kilogram of corn. 11 million bushels (141,590 kilograms) of corn is harvested, exported from the watershed of origin and brought to market in a different watershed. Therefore, the 127.4 million liters of water (incorporated into the corn) is lost to the watershed of origin and considered a virtual water export. Conversely, 1.4 million kilograms of bananas purchased and eaten in the watershed of origin (for the corn) are considered a virtual water import. An estimated 860 liters of water is needed to produce 1 kilogram of bananas, totaling 1,204 million liters of water imported. When only looking at corn and bananas in this watershed, the virtual water balance (-127.4 million liters [of corn] + 1,204 million liters [of bananas]) is a gain of 1,076.6 million liters.

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The Virtual Water Accounting project is using the “VIEWR” formula above to test a new framework that allows for a quantitative analysis of virtual water. The formula is applied in a three-step method, described in detail through a series of summaries:

The VIEWR approach will enable support more effective water conservation programs, water withdrawal management/regulations and cumulative impact assessments on water and related natural resources. The Great Lakes project will pilot the virtual water accounting approach in the Kalamazoo River watershed.

This study has been funded with generous support by the Great Lakes Protection Fund.