When zebra mussels found their way to Lake Ray Roberts last month, or, more precisely, when wildlife officials found that they had found their way there, Dallas let out a collective "Oh, crap." The invasive bivalves were easy to ignore when they were the plague of the Great Lakes and the Upper Midwest. They was harder, but still possible, to ignore when they took over Lake Texoma. Half of that's in Oklahoma, after all, and while the North Texas Municipal Water District had to build a 47-mile pipe, it's water customers in Plano who will have to pay for it. The Ray Roberts discovery was closer to home, the first time the little punks had been found in the Trinity River Basin, in part of Dallas' water supply, no less. It seemed time to start freaking out.
Except Dallas Water Utilities Director Jody Puckett told a City Council committee there's no reason to panic but that Dallas should brace itself for, her words, "the arrival of a pain in the behind." She had a couple of pain-in-the-behind specimens in glass jars that were passed around so the council members could take a look. They were packed in alcohol. Otherwise, possessing them would be illegal.
Puckett then ceded the floor to Dennis Qualls, who heads DWU's water resource planning division. He assured the committee the mussels pose no threat to water quality or access to water. They can disrupt a lake's food chain and ecology but in terms of water supply, they're just a pain.
"They will attach to anything hard," Qualls said. "When I say anything hard, they will attack to each other, rocks, cans, bottles, anything. Which would include our intakes."
The mussels haven't yet reached the city's intakes, which are below Lake Livingston, but they will. "They're on their way. It could take a couple of years to get down to our intakes on the Elm Fork. A couple of years -- two, three, four -- we don't know."
When they do reach water intake structures and other equipment, they will need to be periodically cleaned off, which will increase maintenance costs by an unknown amount. Puckett chimed in to note that Dallas water users won't experience the 14-percent rate hike likely for NTMWD customers. That's because Dallas doesn't have pump stations in Oklahoma and doesn't have to worry about violating federal law by transporting an invasive species over state lines.
So can anything be done to stop their spread, or even slow it? Not really, Qualls said. A good flood during the spring spawning season can spread them within a water basin, and there are any number of ways they can spread between them. A boat, for example. Or a duck that hasn't properly digested his dinner and poops out a live one.
"They'll make their way down to Livingston and to the gulf. It's going to happen."
Qualls reported that researchers are looking at all conceivable methods of mussel control, from chemical or biological agents to acoustics. But Councilwoman Voincel Hill Jones wanted to know about the more obvious form of population control: "Why can't you eat them?"
For one, Qualls said, they're tiny. Lots of work for a little reward. More important, they are filter feeders that accumulate whatever chemicals happen to be in the water. So put away the garlic and white wine, unless of course you want to eat what's in the Trinity River.