City of Bloomington officials say the municipality’s water supply is going through extra filtration to offset issues with taste and odor that have arisen lately.
Issues with the taste and odor of Bloomington’s water tend to surface every year as summer comes to a close, but the severity differs from year to year, said public works director Kevin Kothe.
This year, he said, a lack of rainfall may have made the occurrence especially pronounced. With both Lake Bloomington and Evergreen Lake water levels down, there’s less water movement through the lakes.
If “you experience a decrease in rainfall, it results in the lakes being a little lower and the warmer temperatures help to grow some of the stuff that causes these… taste and odor issues,” Kothe said. Specifically, compounds found in naturally occurring blue green algae on the lakes have contributed to the issue. Less movement from less rainfall has resulted in more growth.
Agricultural runoff into streams and other bodies of water that feed into the lakes can affect the taste, too, but Kothe said that tends to be most pronounced earlier in the year.
“We get a lot of runoff from spring rains in the fields and we’ll have an increase in nitrogen that we have to watch out for, but the more we can do with the farmers upstream and the practice they use for their cropland can directly impact the amount of runoff we get and what we have to do as far as treatment processes go,” he said.
“This is just one of those aspects (happening) at a different time in the year. If there was a little bit more water flow, runoff probably wouldn’t occur in the same way, but each year is a little different.”
Kothe said water treatment workers have slowed down the flow of the water through its carbon filters, allowing the water to have “longer contact” with the filters to remove the compounds that contribute to the taste and odor issue.
The city released a guide to frequently-asked-questions regarding theissue, noting the slowed filtration process will remain ongoing until the issue is resolved.
The document said lab tests show "the water meet(s) all water quality guidelines for health standards" and that it is safe to drink.
