Free-text query terms were recorded from the University of Nebraska Water Quality Web Site. Comparisons were made between 3,275 free-text searches representing 2,075 unique terms and three controlled vocabularies: Library of Congress Subject Headings, Water Resources Abstracts Thesaurus, and Aqualine Thesaurus 2. Between 30 percent and 40 percent of the free-text queries were exact matches to a term in one of the controlled vocabularies. Other user query terms varied from the controlled vocabularies in whether the term was singular or plural, in spelling, and in word endings. About 40 percent of the terms had no near matches. Around 15 percent of the users included a non-subject resource descriptor. Resource descriptions of most interest to searchers were keywords, geographical delineators, and genre/format terms.