March 26, 2009

In Reply Refer To:
Mail Stop 411

OFFICE OF GROUNDWATER TECHNICAL MEMORANDUM 2009.03

Subject: GROUNDWATER: Ground water versus groundwater

It has been a longstanding practice within the USGS to spell ground water as two words and to hyphenate when ground water is used as a modifier (e.g., ground-water hydrology). Ground Water Branch Technical Memorandum 75.03 (http://water.usgs.gov/admin/memo/GW/gw75.03.html) issued just under 35 years ago specified that the two-word form should be used.

Language evolves, and it is clear that the one-word spelling of groundwater has become the preferred usage both nationally and internationally. The one-word spelling has been used by the Merriam-Webster online dictionary since 1998. Most water-resources publications also use the one-word spelling, as do many technical groups, such as the National Research Council. With the emphasis on interdisciplinary science, many USGS scientists who are not specialists in the field commonly use the one-word form, as increasingly do many hydrologists within the Water Resources Discipline.

The term surface water has not seen the same language simplification that has occurred with the term “groundwater.” “Surface water” continues in the English language universally spelled as two words. Use of the two terms together spelled as “groundwater and surface water” has become common usage.

With this memorandum, we are making a transition to the use of groundwater as one word in USGS. Changeover to use of the one-word spelling in our publications and web sites will be accomplished as seamlessly as possible. Reports in preparation should be converted to the one-word spelling where this does not require a special effort. Reports submitted for approval after August 1, 2009, will be expected to use the one-word form. During this transition period, the one-word or two-word spelling should be used consistently throughout a publication.

William M. Alley
Chief, Office of Groundwater

This memorandum supersedes Ground Water Branch Technical Memorandum No. 75.03