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North Texas Bets Big on Pumping from Lake Texoma

Jen Sorensen

At the beginning of the month, I had a column in the paper talking about a study saying the Dallas area is in much better shape than many of the nation's big metropolitan areas in terms of water supply. Now it turns out we're betting the farm and risking the extinction of the entire system.

No good news goes unpunished, in this case by a mollusk, which is being given a big assist by thirsty North Texans.

We all get this: If our water system dies, the region dies. In the search for extra-terrestrial life, they don't look for the planets with no water. Same thing for cities.

This story involves a gamble, not certain doom. We could win this turn of the wheel, but some people who know a lot about the issue wonder why we want to play.

In just a few short years, Lake Texoma has become heavily infested with zebra mussels, a small bivalve mollusk (looks like a little clam) that started showing up in North America in the late 1980s. Scientists think they came here as unwanted stowaways on ships from Central Europe and Eurasia.

Away from natural predators and other conditions that hold them in check in their native lands, zebra mussel populations here explode like nukes in fresh water, sucking the life out of lakes in a few short years. Their capacity to multiply and kill entire food chains is so frightening that they already are considered a serious threat to the Great Lakes.

The Great Lakes are oceans. They hold 21 percent of the world's surface fresh water. If zebra mussels can threaten the ecology of something that vast, what do we think they could do to our reservoirs in North Texas?

Cliff Moore, a North Texas naturalist and critic of current policy on zebra mussels at Texoma, says: "We stand to risk all of the lakes, rivers, streams and wetlands in the state of Texas if we don't quarantine Lake Texoma and stop the movement of these zebra mussels."

But we're about to do just the opposite. Instead of locking up Texoma, we're going to open the spigot and let 'er spill.

The Tulsa District of the U.S. Army Corps of Engineers, which controls Texoma, informed me last Friday they were about to grant permission to the North Texas Municipal Water District (NTMWD) to begin pumping drinking water from Texoma for the first time since pumping stopped in August 2009 to prevent the spread of the mussels.

This action awards us with some dubious firsts. We are about to become the first people in the world to pump massive volumes of drinking water from a body of water known to be infested with these life-strangling mussels. We also are about to become the first people in the world to rely on a system of containment that is much cheaper and simpler than methods in use elsewhere. Our system is untested anywhere else.

Texoma is an 89,000-acre manmade reservoir 70 miles north of Dallas at the Texas-Oklahoma border. The water pumped from Texoma will flow into a creek that flows into Lake Lavon, a 21,000-acre reservoir in Collin County between Plano and Farmersville, owned and operated by the Fort Worth District of the U.S. Army Corps of Engineers. The pumping will be done by the NTMWD, which sells water to suburbs north of Dallas.

It's not that there is no plan to contain the mussels. There is. Andy Commer, the regulatory director for the Tulsa district of the corps, told me the corps was granting permission to pump only after consulting with scientists and engaging in a long process of talks with NTMWD, which devised the original pumping and containment plan.

So we must hope he's right, and the scientists are right and the NTMWD is right. Otherwise we will spew zebra mussels into the entire ecosystem of the region and state.

That's what stops the critics dead in their tracks — the sheer size of the risk. No matter how bad our drought, no matter how much we think we need that water, the risk of putting a bullet in the head of every lake and river in the state is more than some experts on the issue can even fathom.

Jeff Alexander, a Michigan journalist with an award-winning book on the topic, says he can't understand how one reservoir full of water, even a big one, possibly could be worth such a terrifying roll of the dice.

"I would be skeptical that you could pump water from a reservoir that is already infested with zebra mussels into one that is not and not infect the other reservoir," Alexander says. "To me that just seems like Russian roulette at the highest levels."

Zebra mussels spread through a body of water in a phase of their life cycle when they are of microscopic size, like spores, free-floating at all depths and numbering in the billions. They pick up calcium and grow shells as they float, eventually becoming heavy enough to sink. If they hit the right kind of surface when they sink, they grow in huge numbers and begin powerfully sucking in microscopic food sources, devouring so much life that they starve out all the other species at their level of the food chain.

 

The plan for Texoma is to pump water out of the lake only when the water is too cold for the zebra mussel spores to form. A lot of preparation already is under way, including scouring and chlorination of the pipes to kill off any zebra mussels that may already be in there. Chlorine kills them.

The agreement between the corps and NTMWD requires the water district to test for spores around the intake pipe before pumping. Commer told me the water temperature has already fallen below the required threshold, but the tests for spores are still turning up too many of them. When three conditions have been met — water cold enough, no spores near pipe, pipes scoured — pumping may begin.

That may sound like a lot of precaution. But on the Great Lakes it wouldn't be anywhere near enough. Cities that take drinking water directly out of the lakes do much more to protect themselves from the mussels than the Texoma plan envisions.

They chlorinate the water they take from the lakes at the point of intake — at the mouth of the pipe — and then if the water is to be stored in a reservoir elsewhere, they dechlorinate it to protect the reservoir. It's a complicated, capital-intensive process.

Too expensive for us, apparently. Brandon W. Mobley, a natural resources management specialist for the corps' Fort Worth District, told me: "To get a system like that online would take some time, and, this is just me speaking, it's cost-prohibitive in certain elements."

But Commer in the corps' Tulsa District conceded that no one else in the world has ever tried to do it the way we will, with no chlorination, relying instead solely on water temperature.

"This is the first situation in the world where water temperature with regard to the metabolic process in the mollusk is being used as a control threshold," he said.

There are other ways for zebra mussels to get around, notably on the bottoms of fishing boats hauled from one lake to another. For that reason a number of lakes in Southern California have been quarantined to boats — that is, nobody can bring a boat in from another lake.

We're not doing that either. Mobley told me the corps is looking at similar plans for its North Texas lakes, but so far the only policy is to rely on boat-owners to spray off their boats before transferring them.

None of this is to say the proposed prevention methods are crazy-irresponsible or drunk or wicked or anything like that. Even Cliff Moore, the naturalist who thinks Texoma should be sealed off, says, "If the monitoring (for spores) really has some oversight, it's not necessarily a terrible plan.

"But can we risk the billions it's going to cost us if they're wrong?"

Moore believes the water lobby and the recreation and real estate lobbies have combined forces to create an attitude of denial toward the risk. "They used to say, 'We don't have to worry about it in Texas. Zebra mussels won't move this far south.'"

If there were ways to poison them in large bodies of water or introduce some predator to kill them off, people would be doing it. It's not physically realistic or safe to chlorinate entire reservoirs. Research is under way into methods of prevention or eradication, but so far, once the zebra mussels have got you, they've got you. And once they find a pathway, however narrow, their spread is explosive.

Because their suctioning power is so vast, zebra mussels have the effect, at least for a while, of rendering lakes crystal clear. Denise Hickey, public relations coordinator for the NTMWD, which wants to pump the water, told me that zebra mussels have "no effect on water quality" for drinking purposes.

She said, "From an environmental perspective, they act as a natural filter in a reservoir."

That's not untrue, with the possible exception of the word "natural." As an invasive species, away from their natural habitat in Europe and Asia, their filtering power is less natural than monstrous: They kill everything else with one exception: blue-green algae.

At certain concentrations, blue-green algae can break down and release a whole family of neurotoxins into the water. Fish kills, bird die-offs and human fatalities have been reported.

 

Even short of that, it's hard to see how killing all the life in lakes could be a good thing. This may be one of those instances when we need to break out of our parochialism, look around and ask ourselves, "Why is everybody else taking this problem so much more seriously than we seem to be?"

Is everybody else an idiot? Are we geniuses? Are we sure we know what we're doing here?

North Texas Bets Big on Pumping from Lake Texoma

Environmentalists fear plan will let invasive zebra mussels spread.


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