While in Baltimore, I had a chance to catch up with Susan Hutson and talk about the USGS Water-Use Program. In any water-supply study, you’d think the most elemental question would be, “How much water is being used?” Few of us realize how difficult it can be to come by this data.
Problem is, one rarely can go out and measure water use; data typically have to be provided by others or estimated by various methods. Public water utilities can provide information on domestic and commercial use — if metered — but their customer categories follow no consistent definition. Private domestic wells rarely are metered, so use must be based upon housing or population characteristics. Irrigation use is even harder to estimate, especially if supplied from groundwater. I don’t think we appreciate the skill required to make reasonably accurate estimates of water consumption that can be compared consistently from year to year.
The United States Geological Survey has a nation-wide program for estimating water use. It’s run on a shoestring, but specialists for each State compile an estimate of water use for each county every 5 years. They’ve been doing this since 1950. Techniques have changed — GIS being the most prominent advance — but every effort is made to keep the numbers comparable, so trends can be evaluated.
It hard to say what the rest of the world does. I am unaware of any other nation that runs a comparable nation-wide program. Individual utilities may know much about their customers, but not much about self-provided water. Also, it is not too unusual for a utility to report as much of half its water “missing,” so how good can estimates be in these circumstances? One must wonder if we are basing plans upon on a house of cards. The skillset developed by USGS for estimating water use needs to become more widely available to the world.