Workers are making emergency repairs to a broken sewer line that is spewing about 1 million gallons of wastewater per day into a Mississippi River tributary in Memphis, an official said Wednesday.

This is the third sewage spill in Memphis in the past three weeks.

The break in the 42-inch sewer line was discovered Sunday by a resident who was using the Loosahatchie River and confirmed Monday by a city inspector, Public Works Division Director Robert Knecht told reporters at a news conference. Knecht says the pipe ruptured when nearby soil eroded and gave way due to heavy rains.

Public drinking water is not affected, Knecht said. Officials are warning residents to avoid contact with the Loosahatchie, which flows into the Mississippi River. Crews are hoping to stop the leak within two days, Knecht said.

Tennessee Department of Environment and Conservation officials were going to the site of the leak Wednesday to take samples of the river for water quality testing, department spokeswoman Kelly Brockman said.

A 96-inch pipe collapsed March 31, sending 50 million gallons of sewage per day into Cypress Creek and adjoining McKellar Lake, which also flows into the Mississippi River. The spill caused a major fish kill and led to high levels of E.coli in both bodies of water. Knecht said record rainfall amounts in March caused the soil to erode and an embankment to fail, similar to the most recent leak.

The March 31 leak was stopped a week after it was reported. A second, much smaller leak was discovered while crews were working to fix that leak.

The pipe that is spilling water into the Loosahatchie was inspected in November, and no problems were found, Knecht said.

The city inspects sewer lines twice a year, Knecht said, but his department is working on a "serious inspection regimen" to determine the condition of main sewer lines in vulnerable areas in the next 30 days.

"We have to do a detailed and dedicated assessment and look to identify any other issues that are occurring so that we can address them immediately," Knecht said, adding that the city has 3,200 miles of underground sewer pipes.

In 2012, the Department of Justice, the Environmental Protection Agency, TDEC and the state attorney general reached a settlement with Memphis over a complaint filed together with the Tennessee Clean Water Network against the city for alleged violations of the federal Clean Water Act and the Tennessee Water Quality Control Act.

The city agreed to make improvements to its sewer systems to eliminate unauthorized overflows of untreated raw sewage, work estimated to cost approximately $250 million. Knecht said the city could face fines due to the spills and the environmental damage they have caused.

Scott Banbury, conservation program coordinator for the Sierra Club's Tennessee chapter, said he believes the city is doing a decent job of fixing the problems under the settlement, but the leaks may be a result of years of neglect.

"Over the years, there was not appropriate resources applied to maintenance and inspections ... and actually taking steps to mitigate problems appropriately," Banbury said.