SAVANNAH - Deepening the Savannah River, geologist Fred Rich worries, might widen cracks in the rock shielding our drinking water.
Since 1996, the Georgia Southern University professor has poked about in road cuts and stream beds from Bulloch County to Sapelo Island studying cracks. He's concerned that the proposed deepening of the navigation channel will worsen fissures he's found in the Miocene layer of rock that rests on top of the Floridan Aquifer - the porous underground limestone formation that holds drinking water for much of the Southeast.
The cracks he's studied seem to be everywhere. He doesn't doubt they are under the Savannah River, too.
Disturbing the cracks could let saltwater into the aquifer, Dr. Rich reasons. And dredging the channel deeper could disturb the cracks.
The questions Dr. Rich and others have raised have shifted the debate over the environmental impact of deepening the channel. The Georgia Ports Authority's environmental stakeholders group, charged with crafting scientific studies about the deepening, have formed a special aquifer subcommittee.
"The bad thing about aquifers is, once they get contaminated, you really can't clean them up," Jim Henry, another scientist concerned about the cracks, said at the aquifer subcommittee's first meeting.
David Schaller, deputy executive director of the Georgia Ports Authority, dismisses the idea that the project could harm the aquifer.
Mr. Schaller said that if the project had an adverse effect on state water quality standards, it would not get a water quality certification permit.
But despite Mr. Schaller's reassurances, environmental concerns over the deepening have shifted from preserving freshwater marshes along the river to preserving freshwater for the coast.
One of the reasons the debate has shifted is that Mr. Rich's investigations bring new data to bear on studies completed in 1997 and 1998 that were used to justify the deepening project.
A 2-year-old Army Corps of Engineers study indicates deepening the channel from 42 to 48 feet does not threaten the drinking water supply held in the aquifer.
There is already some saltwater seepage from the Miocene into the limestone of the aquifer under the river, said Cardwell Smith, a Corps of Engineers hydro-geologist. Right now, it's not enough to impact the quality of the water in the aquifer, he said. And deepening the harbor to 48 feet will not make the seepage any worse.
But other scientists say that cutting deeper into the fissures would let contaminating saltwater into the aquifer, especially because the system is under other stresses such as the drought and saltwater intrusion around the edges.
The deepening is needed, according to the Ports Authority, to better accommodate deep draft ships calling on the port. Without the deepening, those ships would be forced to call on other ports, costing the state millions in lost business.