My Georgia-born mother used to say, "Time is short and the water's risin'."
I think the expression was the title of a recent memoir, but couldn't find it on Amazon.
Is anyone familiar with its origin?
The only thing I found is this:
Time Is Short and the Water Rises, Operation Gwamba: The Story of the Rescue of 10,000 Animals from Certain Death in a South American Rain Forest. Hardcover – January, 1967
by John Walsh (Author), Robert Gannon (Author)
This seems too recent (1967) to be the source of a folk saying. However, the title could come from an older saying, which I have not been able to find so far.
A candidate for an older saying which your mother and her neighbors might have adapted is:
God willing and the creek don't rise
Note that the time is short is a Biblical saying (Paul, 1 Corinthians 7:29), which is extensively discussed at Biblical Hermeneutics Stack Exchange. It is thus possible that your mother's community combined a Biblical saying warning that time is short with an old regional saying about the rising [waters of the] creek (or crick). More Research is Needed.