A blue-green algae presence at Boerne City Lake continues to “muddy the water,” so to speak, about the city of Boerne utilities system’s water supply.
Recent reports of earthy -- or “dirty” -- tasting and smelling water have been reported for several weeks. Michael Mann, Boerne’s utilities department director, updated Boerne City Council during its November 14 meeting on the issue, its effects, and expectations for its dissipation.
“We’ve had this issue before (with water from Boerne City Lake), usually very short-lived, just a matter of days,” Mann said. “Not a lot of people notice, typically.”
But this instance has remained for almost a month -- with no perceived end in sight. “What's new about this one,” Mann said, “is rather than being gone in days or a few weeks, it’s been persistent and right now, we don’t know when it’s going to end.”
Chris Shadrock, Boerne director of communications, said while there is a noticeable change in the taste, the quality of water continues to meet or exceed regulatory requirements.
“Since the earthy taste became noticeable, we have taken additional samples of the water, and nothing has come back indicating any issue that would be cause for concern,” Shadrock said.
While the situation continues to be a nuisance, Mann told council, there is no health concern with the water being delivered to customers.
Blue-green algae, he said, produces something called geosmin. Geosmin has a distinct earthy or musty odor, which most people can easily smell.
“It is a common problem for a lot of utilities, especially those which are almost exclusively a surface water supply. Not a very common problem for us,” he said. “It happens, but not to the extent it has now.”
The sources of research he reviewed in the past several weeks say the blue-green algae/ geosmin is not a health concern, “but it is a nuisance. Nobody likes it. I don’t blame customers for being concerned about it.”
A 2004 article in a Water Supply and Technology publication said municipal water treatment facilities have reported that geosmin cannot be removed from water using standard treatment processes. Treating for geosmin requires additional treatment, which may not be available to all municipal water suppliers.
Mann verified such is the case with Boerne’s water filtration systems.
The city’s water treatment plant was built in the 1970s and has been updated several times over the years, for chlorine, manganese, and a few other treatments.
“But conventional water treatment just can’t treat it,” he said. “You have to have a treatment process to remove it.”
“Water treatment plants equipped with granular-activated carbon (filtering) is the ‘gold standard’ for removing geosmin,” he said. “If we had that in place, we could treat the geosmin problem we’ve been having.'
Carbon filters, he said, “are very expensive. It will take probably millions of dollars to install at all three storage tanks, but we’re going to have to do it.”
In the meantime, he said, “We’ll continue monitoring and testing the raw water to see if we can tell when this thing ends.”
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