The flood sequences were actually filmed in and around
Santa Cruz, California.
Special effects supervisors Jack Smith and Roy Davidson built
miniature sets that could realistically collapse under moving water. A local lumber company and local buildings were used as
sets.
Film historian Robert A. Harris considers the film remarkable for its time, because of the vivid way it recreated the flood, saying: "The importance of
The Johnstown Flood to film history is difficult to overstate. The special effects of the film combine miniatures and sets to depict the actual historic event of flood and its aftermath, pioneering complex techniques. It was the
Star Wars of its day." ==Cast==