To Catherine Coleman Flowers, this is “holy ground”: the place where her ancestors were enslaved and her parents fought for civil rights and she came of age. Here, amid the rich, dark earth and emerald farm fields, she is home.

Yet this ground also harbors a threat, one that will worsen as the planet warms.

For decades, the people of this rural county 30 miles south of Montgomery have struggled with waste. Municipal sewage systems do not extend to this farming community, and many residents cannot afford septic systems; their waste flows directly into ditches or streams. Even those with septic tanks find that they often fail in the dense, waterlogged soil. On rainy days, toilets won’t flush and foul effluent burbles up into bathtubs and sinks.