Thurmond Lake and other Savannah River reservoirs were in flood control stages Thursday after 3.75 inches of rain fell in some portions of the basin.
Locally, ponds overflowed and streets in low-lying areas of Columbia and Richmond counties were closed because of flooding - and stormwater surges in Augusta caused a sewage spill in excess of 440,000 gallons.
Storms in Aiken County knocked out power and flooded streets.
The Army Corps of Engineers cut releases from Thurmond Dam into the Savannah River late Wednesday in anticipation of pending heavy rains, Corps spokesman Jim Parker said. Further reductions were ordered Thursday.
"Right now, we have all three lakes in flood control because we're above the summer pool levels," he said.
About 2 inches of rain fell at Thurmond Dam on Thursday - with additional rain in the forecast. Rainfall amounts ranged from 2.75 to 3.75 inches across the Savannah River Basin.
Thurmond Lake was at 331.01 feet above sea level Thursday afternoon - more than a foot above normal. Mr. Parker said the lake will rise quickly because of reductions in releases from the dam into the river.
"We cut back pretty dramatically yesterday, from 23,000 to 11,000 cubic feet per second," he said.
The reservoir is expected to rise to 333 feet or more before it can be brought back down.
Curtailing the flow from the lake into the river uses the 70,000-acre reservoir as a storage vessel. Water held there reduces river flow and allows heavy rains between the dam and Augusta to dissipate.
Once local rains have diminished, releases from Thurmond Dam can be increased to bring the lake down to normal levels. Although full pool is 330 feet above sea level, the lake can store water up to 335 or 336 feet.
In Columbia County, where up to 2.5 inches of rain was reported, deputies and utility crews responded to road problems, fallen trees and flooding complaints before rainfall subsided at midday.
"Before daylight today there was a lot of teamwork going on out on the roads - deputies with chainsaws trying to clear trees out of the roadway," said Emergency Services Director Pam Tucker.
In Columbia County, Stevens Creek, Reynolds Farm, Marshall, Moontown and other roads were closed briefly.
"Reed Creek was rising a foot an hour, and that's when it began crossing over the road," Ms. Tucker said. "That bridge is soon scheduled to be raised, so maybe this will be the last time in history."
In Aiken County, about 200 customers lost power when thunderstorms passed through Aiken County late Wednesday, officials said. Brian Duncan, a spokesman with South Carolina Electric & Gas, said the outages were scattered throughout the county and crews were able to get power on again in nearly all areas.
Crews were still dealing with a handful of sites in the county Thursday evening, Mr. Duncan said.
Creeks in Aiken County flowed out of their boundaries, especially in the Midland Valley area around South Carolina Highway 421. Officials said there was standing water in some roads, but no major flooding.
Jefferson Energy Cooperative experienced a power outage that affected 2,000 customers in 11 counties. The power was restored by 10:45 a.m.
Minor flooding was reported in the Hereford Farm Road area and Gibbs Road, near the Walnut Hill Subdivision.
The flooding also affected Columbia County's Special Olympics, scheduled for today but rescheduled for March 28 at 9:45 a.m. at Greenbrier High School.
Staff Writer Matt Boedy contributed to this article.
Reach Robert Pavey or Melissa Hall at (706) 868-1222.
