Bloomington Utilities customers may notice yellow or brown discoloration in their water over the next few days due to elevated levels of manganese in the city’s water intake from Lake Monroe, according to Bloomington Water Quality Coordinator Justin Meschter.

“We're taking water a little deeper than we usually do,” Meschter said. “We're having trouble removing all of that manganese from the raw water coming from the lake.”

Meschter said CBU’s manganese levels peaked at 0.24 milligrams per liter, which is below the U.S. Environmental Protection Agency’s advisory levels.

Currently, there isn’t an enforceable maximum contaminant level for manganese in drinking water. However, EPA guidelines state that adults should not drink water containing more than 1 milligram of manganese per liter, while infants should not drink water with more than 0.3 milligrams per liter for more than 10 days.

“The EPA says the water is still safe to use,” Meschter said. “It's okay to use for bathing, for showers, for drinking.”

Meschter said the elevated manganese levels should not harm consumers’ plumbing or the distribution system, but he recommended checking water filters more often while the discoloration continues.

CBU is working to flush the discolored water from the distribution system and replace it with water containing lower levels of manganese. Meschter said the discoloration should be resolved before the weekend.

“If you run your taps a little bit when you go to use your water, that can help to kind of remove some of that discoloration for any of the oxidation that occurred within your internal plumbing,” Meschter said.

He said consumers experiencing continued discoloration after a couple days can email wq@bloomington.in.gov.

Meschter said the elevated manganese levels are the result of low oxygen concentrations in Lake Monroe, which cause manganese to dissolve into the water.

Algae on the lake’s surface is contributing to the problem by limiting the amount of sunlight and oxygen that reaches deeper water, he said.

As the water enters the distribution system and encounters higher levels of oxygen, the dissolved manganese oxidizes and begins to precipitate, producing the yellowish-brown discoloration.

Meschter said a similar process occurred last year, although it was caused by heavy spring rainfall that increased the lake’s depth, creating low-oxygen conditions deeper in the water.

“I know it's a little off-putting when there's a little bit of discoloration to the water,” Meschter said, “but as far as the safety of the water goes, you know we have no reason to believe that the water is not safe.”