Seeking to explain its recent problems with stinky, bad-tasting water, the city of Atlanta is now pointing to a new culprit — algae bloom.

Officials say a sudden proliferation of algae is why some of the city's 1.2 million customers have been forced to pinch their noses to gulp down drinking water since last Friday.

"It's not an uncommon problem, but it hasn't happened here in a while," Janet Ward, spokeswoman for the city's Department of Watershed Management, said Monday.

Conditions apparently became ripe for algae to grow in the city's water reservoir. Such "blooming" algae depletes water of oxygen, causing a musty smell and a bad taste, Ward said.

Water officials are using copper sulfate in hopes of clearing up the problem in a matter of days. Meanwhile, the water has been tested and remains safe to drink, Ward said.

Department officials had first blamed the situation on "reservoir turnover," which happens when cool water heats up and rises, bringing with it sediment and algae.

Not all customers are affected and the problem isn't confined to any particular area. Atlanta serves the city, Sandy Springs and unincorporated south Fulton.