Interbasin water transfers: An appropriate management practice for the Great Lakes?

Regional water deficiencies exist in North America, and proposals have been advanced to ‘correct’ these by transferring water from regions where it is relatively abundant to regions where it is relatively scarce. Many of these proposals identify the Great Lakes as either a potential source of the water, or as a ‘distribution centre’ into which water may be transferred and subsequently removed to regions experiencing deficiencies. Although the Great Lakes contain a very large amount of fresh water, most of it is required in place, and so many not be removed. The Great Lakes Basin is heavily populated and highly industrialised, creating a large water demand for consumptive uses, particularly municipal supply, manufacturing and thermal power generation. Commercial shipping and hydro-electric power generation are also vital to the region, and are adversely affected by even a slight reduction in water levels in the Lakes and their connecting channels. Further, recent studies suggest that the on-going accumulation of certain gases in the atmosphere is causing an overall increase in average air temperatures globally: this is expected to reduce the quantities of water present in the Great Lakes Basin even while the region becomes increasingly dependent upon them. Through the use of an index, ɸ, which relates available water supplies to the quantities committed to human use, the degree of allocation of supplies in each sub-basin is calculated. Under reliable flow conditions, ɸ values of greater than unity are found for each sub-basin, implying that periodic water deficiencies occur more than 5% of the time. In the future, periodic water deficiencies are expected to occur with still greater frequency, especially if a large-scale transfer should be implemented. It is concluded that a transfer of 283 m3s-1 out of the Great Lakes Basin is an inadvisable management option. The thesis makes three contributions to current knowledge: a means of quantifying instream water requirements is described; the Great Lakes Basin is shown to experience periodic water deficiencies, rather than the surplus of water commonly assumed; and a transfer of water out of the region is shown to be inadvisable, since there is no surplus available for transfer.