This twenty-seventh volume in the Hardy Boys mystery/adventure series was produced by the Stratemeyer Syndicate and was published by Grosset & Dunlap in 1948 under the house pseudonym Franklin W. Dixon. All but a handful of the earlier books in the series had been ghost-written by the great Leslie McFarlane, but this one was the sole contribution to the series by George Waller, Jr., with considerable input from Harriet Stratemeyer Adams, who also served as the outliner and editor. Grosset & Dunlap undertook to revise the first thirty-eight of the original books from 1959-1973, a project overseen by Stratemeyer-Adams, and David Grambs did the re-tooling of this novel, which appeared in 1966. The idea was to shorten and simplify the books for a younger readership and dated references and other details were changed. The original novel was 212 pages long and had 25 chapters, and the newer iteration was 20 chapters with 177 pages. I read the original edition and then the newer novel back-to-back in order to compare the two. They're quite similar books; many of the revisions are entirely new novels, but this one is mostly just shortened and simplified, with less characterization and humor and more action oriented. It's a good story that focuses on a scientific mystery more than on criminal activity. Their hometown, Bayport, is having a water shortage, which is supposed to be alleviated by the construction of a new reservoir created by the damming of the Tarnack River. Unfortunately, the water level doesn't rise; it seems to act as it should during the daytime but drops at night. Frank and Joe sign on to help the engineers who are investigating the problem and soon encounter a variety of quirky characters who are opposed to the project. (There's a Native American burial ground on the mountain, and it's a little disturbing that their skulls are dug up and tossed around with no thought as to wrongdoing. Also, poor Chet is constantly overeating and clumsily plump throughout both books.) In the meantime, Dad Hardy is looking for a missing scientist from Chicago, and of course their cases overlap. Most of the changes between the editions are slight, aside from the simplification. A reference to Saturday night baths is changed to a swimming pool, Police Chief Collig is no longer gruff and grumpy in '66, and Callie Shaw's undercover job is changed to a consortium of lookout girls. In the original, the kidnapped scientist is made to test for bauxite deposits, but that's changed to cesium in the new one, which actually makes a lot more sense. Altogether, the quality of the book doesn't drop as much as I'd anticipated with McFarlane's absence. I rated the original at four stars and thought it appropriate for an average age of 12-14, and the revision at two stars for, say, 8-to-10.