Avon Books, 1983, 895 pages
Blackwater is the saga of a small town, Perdido, Alabama, and Elinor Dammert, the stranger who arrives there under mysterious circumstances on Easter Sunday, 1919. On the surface, Elinor is gracious, charming, anxious to belong in Perdido, and eager to marry Oscar Caskey, the eldest son of Perdido's first family. But her beautiful exterior hides a shocking secret. Beneath the waters of the Perdido River, she turns into something terrifying, a creature whispered about in stories that have chilled the residents of Perdido for generations. Some of those who observe her rituals in the river will never be seen again....
Southern Gothic, with Deep Ones.
Also by Michael McDowell: My review of The Elementals.
My complete list of book reviews.