Wade in the Water-
Published sheet music prior to 1923- Everything published up to about 1940 was collected in the field, of a traditional song and its variants. It is not a composed song by a known author, and musical scores of some collected versions were printed in books by the collectors. A good example:
Lydia Parrish, 1942 and reprints, "Slave Songs of the Georgia Sea Islands," University of Georgia Press. Songs collected from Gullah culture. Original copyright Lydia Parrish 1942, with later copyrights by Maxwell Parrish and Brown Thrasher Editions.
1992 edition, pp. 170-171, lyrics and musical score.

WADE IN NUH WATUH CHILDUN
chorus:
Wade in nuh watuh childun
Wade in nuh watuh childun
Wade in nuh watuh
Gawd's go'nah trouble duh watuh.
How long this song had been sung by the Georgia Sea Island inhabitants is unknown.
As long as you ask permission to use a version in your work, I don't think you will have any problems.
Allmusic.com lists almost 150 versions- as long as you don't exactly copy the version or style of these various people, you 'should' be all right (he, he!).