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The Handcox Water Treatment Plant, near the intersection of 620 and 2222 is where the zebra mussel problem was found. The invasive shellfish were on all three intake pipes.
Images sent to FOX 7 Austin show how mussels were clustered on screens designed to keep debris from being sucked into the plant. The intake near the surface had the most blockage, according to Water Treatment Operations Manager Mehrdad Morabbi.
"So we saw about 50% of the screen was covered. And the lower one which is roughly 50 feet or so below that top intake, the middle intake was somewhere between 20 to 30% coverage,” said Morabbi.
The utility was expecting this underwater invasion.
Read Boaters beware of transporting zebra mussels
Earlier this year Lake Travis was classified as being one of several lakes in Texas infested with zebra mussels. To address the problem, Austin Water signed a $212,000 contract with a diving company to clean off the intakes. Morabbi does not believe this new annual expense will be passed on to rate payers. "I can only speak for my area which is water treatment, I think that is something we can absorb in our budget, in water treatment, so no I don’t expect us to have a rate increase associated with that."
Inspections at two water intakes on Lake Austin are planned for this winter.
But the utility already knows there's a problem. "So we've seen them on our Ph meters, they're actually growing, we are also seeing them in some of the ancillary equipment to our pumps we have strainers to cool the pumps so we've seen them in the strainers," said Morabbi.
While zebra mussels can reduce water quantity, they do not affect water quality
Local divers say they first spotted zebra mussels in Lake Travis about a year ago.
Read Invasive species makes home in Round Rock’s water intake
One of those drivers, Robert Weiss, described how quickly things changed. "Last year we saw one or two and we were amazed, aw here is a zebra mussel, I can't believe we've seen one. It was a surprise to actually see one. Now they’re in every location where we dive,” said Weiss.
Zebra mussels not only cause problems for water utilities but also for swimmers. "You are susceptible to getting cuts juts by bumping against these things, they are everywhere,” said Weiss.
Lakes are infested by the transfer of water; and not just from boats. Zebra mussel larvae can live for several hours in swimming gear, even water shoes. That’s why it’s believed they’re now in Lady Bird Lake and pose a threat to Barton Springs Pool.