Garrett Weiss, the city's stormwater and environmental section manager, said new tests show dramatic improvements in water entering the river from Forsythe Street in Olde Town.
The Augusta Utilities Department, which used smoke pumped into storm drains to help identify the source of the contamination, found a leaky pipe in a private apartment building that was discharging about 5,760 gallons of sewage per day into a storm drain that empties into the river.
Flushing chlorinated water from a fire hydrant through the drain likely corrected the problem temporarily, and officials continue to work with the property owner for a permanent fix.
The Utilities Department also reduced elevated fecal coliform levels in the canal's third level, where new tests found almost no contamination.
"Those numbers are very encouraging," Weiss said. "It appears two small-scale separation projects the department recently completed between Walton Way and Laney-Walker, east of Gordon Highway, have had rapid and dramatic results in reducing coliform concentrations discharging to the canal."
Authorities continue to seek the source of elevated bacteria levels found in another Olde Town storm drain that enters the river near Second Street, he said.
In Columbia County, two leaking sewer pipes -- both on private property -- are suspected of contributing to elevated fecal coliform levels found in the 33-acre lake in Woodbridge subdivision.
The largest such leak involved a missing cap on a sewer line extending across Mount Enna Branch, which flows into the lake, said Bill Clayton, the county's water utility director.
"The creek is not a place for raw sewage, and that's what it was," he said, adding that the problem was corrected at the request of county officials.
A second leak, also in Mount Enna Branch, was identified last weekend by a team of Augusta State University students who are conducting a water quality study of the lake.
"It was a small split in one line, so we got an environmental officer out there right away to notify the homeowner to get it fixed," said Margaret Doss, the county's water quality manager.
The contamination of the water sources came to light as part of a project last month by The Augusta Chronicle . Water samples from 50 locations were analyzed for a story on water quality and bacteriological monitoring.