Interbasin water transfers in the United States and Canada.

Interbasin water transfers (IBTs) can have a significant impact on the environment, water availability, and economies within the basins importing and exporting water, as well as basins downstream of these water transfers. The lack of comprehensive data identifying and describing IBTs inhibits understanding of the role IBTs play in supplying water for society, as well as their collective hydrologic impact. We develop three connected datasets inventorying IBTs in the United States and Canada, including their features, geospatial details, and water transfer volumes. We surveyed the academic and gray literature, as well as local, state, and federal water agencies, to collect, process, and verify IBTs in Canada and the United States. Our comprehensive IBT datasets represent all known transfers of untreated water that cross subregion (US) or subdrainage area (CA) boundaries, characterizing a total of 641 IBT projects. The infrastructure-level data made available by these data products can be used to close water budgets, connect water supplies to water use, and better represent human impacts within hydrologic and ecosystem models.

Comparison of potential drinking water source contamination across one hundred U.S. cities.

Drinking water supplies of cities are exposed to potential contamination arising from land use and other anthropogenic activities in local and distal source watersheds. Because water quality sampling surveys are often piecemeal, regionally inconsistent, and incomplete with respect to unregulated contaminants, the United States lacks a detailed comparison of potential source water contamination across all of its large cities. Here we combine national-scale geospatial datasets with hydrologic simulations to compute two metrics representing potential contamination of water supplies from point and nonpoint sources for over a hundred U.S. cities. We reveal enormous diversity in anthropogenic activities across watersheds with corresponding disparities in the potential contamination of drinking water supplies to cities. Approximately 5% of large cities rely on water that is composed primarily of runoff from non-pristine lands (e.g., agriculture, residential, industrial), while four-fifths of all large cities that withdraw surface water are exposed to treated wastewater in their supplies.

Water Supply Risk in the United States 2015-2050 Considering Projected Changes in Population and Thermoelectric Power Demand.

Examination of water supply risk is important to identify areas of potential insecurity and prioritize allocation of resources. This work builds on and advances a previous U.S. water supply risk analysis developed at county-scale resolution, which did not account for water flow between counties and identified some counties on major rivers as being at high risk. This limitation is addressed in the present study. The analysis utilized data from U.S. Geological Survey water use reports to assess current water supply risk and also projected water supply risk in 2050. Flow volumes were calculated using the Water Supply Sustainability Index (WaSSI) tool developed by the USDA Forest Service, enabling the analysis to account for changes in climate and hydrology and changes in water demand. A modified Water Risk Index (WRI) was formulated, including five factors to which scaled values were assigned. Results indicate that accounting for natural transfers of water in counties in addition to local precipitation reduced the risk profile of many counties, with a maximum of 36 classified as high or very high risk, compared to over 400 identified in the highest risk category in the previous analysis.