Juliet McKenna has done a fantastic back-of-the-envelope calculation about potential effect of dust created by Las Vegas, Nevada’s proposed groundwater pumping system.

Vegas, you’ll recall, wants to build a pipeline across the state, using groundwater from distant rural areas to fuel growth in that state’s largest metropolis.

McKenna notes that various analyses of the project have projected increasing dust as the groundwater pumping dries out the source region. Then she tries to connect the dots with recent studies of the impacts of dust-on-snow:

It has been estimated that dust events in the Rocky Mountains of the Upper Colorado River Basin could cause up to a 5 percent reduction in annual runoff to the Colorado River. More information from the National Academy of Sciences is here, and here. As an example, 5 percent reduction in runoff amounts to 700,000 AF of 14 MAF Colorado River of annual runoff. While this may be an overestimate both of the Colorado River’s annual flow and the reduction caused by dust, even a 1 percent reduction in a record low flow would still amount to more than 100,000 AF/year – more than the amount of groundwater pumping approved for Nevada. As a comparison, Nevada has an annual allocation of 300,000 AF of Colorado River water.