Indiana’s abandoned coal mines contain up to 172 billion gallons of water, according to a recent study. This is water that filters down through the ground and coal seams, pooling in the abandoned mines.

In Indiana they’re beginning to discuss what to do with the water…whether it could eventually be used to supplement drinking water, or for agriculture or industrial uses. But in Kentucky, geologists have been studying water stored in the commonwealth’s abandoned mines for years.

There are several communities in Eastern Kentucky (in Floyd, Letcher and Harlan counties) that are already using water from coal  mines—either as a primary source of drinking water, or to supplement public systems during dry seasons.

Jim Dinger was the head of the Kentucky Geological Survey’s Water Resources division until he retired in 2012. He says he can see a time in the fairly near future when other communities might need to tap into these water supplies.

It’s important because it’s going to act, in some cases, as a primarily supply as surface water becomes more degraded,” he says.

This could be especially important in Eastern Kentucky, where large rivers and lakes are rare. And even with bodies of water like Lake Cumberland, it’s difficult to pump adequate water over mountains to rural areas.

“Local sources of drinking water need to be found,” Dinger says. “And these mines represent a source, but on and individual level they need to be studied as to how the water quantity in the mine fluctuates over years, and how the water quality changes with that fluctuation in water level.”

Dinger says in general, the older the mine, the cleaner the water. That’s because over time, new mine faces are exposed to the elements, and the mineral content is flushed out. But every source needs to be studied, and many of the abandoned mines contain water with high levels of dissolved solids and sulfate. At certain levels, that’s hard to treat, so ultimately using the water comes down to economics and how badly a community needs the extra supply.

Erica Peterson reports on energy and the environment for WFPL. She is also Enterprise Editor.