Flows from Thurmond Lake into the Savannah River will be reduced next week as declining water levels reach a critical point in terms of the need for water conservation.
The Army Corps of Engineers manages the lake - and Russell and Hartwell reservoirs upstream - under a Drought Contingency Plan devised in the wake of the 1980s drought to minimize the impact of low water.
The drought plan has been in its second phase of conditional operations, which require incremental cutbacks in hydropower generation - and releases of water from the dam into the Savannah River above Augusta.
The releases currently are at a reduced rate - 4,500 cubic feet per second - and are expected to be cut to 3,600 cubic feet per second next week, when lake levels fall to 316 feet above sea level - triggering the drought plan's critical Level III.
"At 3,600, we're just barely getting by in terms of water quality in the river," Corps spokesman Jim Parker said. Reduced flows into the river could slow the decline of Thurmond Lake but cause problems downstream.
Augusta's factories use water for operations - and use the river as a conduit into which millions of gallons of industrial sewage flows each day. Treated municipal wastewater also enters the river.
Those entities have permits from Georgia's Environmental Protection Division, which bases the volumes of waste allowed into the river on minimum flows needed to dilute the sewage.
Mike Creason, EPD's industrial wastewater unit coordinator, said state regulators are watching the situation but likely would avoid any intervention if violations occur because of low flows in the river.
"If weather conditions get extreme enough, the regulations aren't going to be met," he said. "But you can't realistically put it all on the backs of users."
This weekend's rains, while welcome, are not expected to help the situation, officials said.
Theoretically, EPD could take some emergency regulatory action such as asking industries to limit operations to reduce wastewater flows, but no such activities are foreseen, Mr. Creason said.
"If it drops below that minimum flow, you may in fact suffer some adverse water quality effects," he said. "But temperature, in addition to flow, has a major impact on how fast waste is assimilated, and we're a little better off with the low flows coming up as we get cooler weather."
Thurmond Lake is designed to be able to fall as low as 312 feet above sea level, at which time releases into the Savannah River would be calculated to match inflows, Mr. Parker said.
The 1980s drought lowered the lake to about 313 feet - just a foot over the point at which the turbines could not operate.
Reach Robert Pavey at (706) 868-1222, Ext. 119, or firstname.lastname@example.org.