MELISSA BLOCK, host:
Until two weeks ago, Lake Pontchartrain was an environmental success story. Pollution had decreased dramatically over the last 15 years. It was safe for swimming. Even manatees returned. Then Katrina came, and officials were forced to pump the polluted floodwaters from New Orleans into the lake. NPR's Elizabeth Shogren was at Lake Pontchartrain earlier this week. As she reports, the lake seems to be withstanding the blow.
ELIZABETH SHOGREN reporting:
Ann Reams(ph) stands on Lake Pontchartrain's north shore. She's spent the last 15 years of her life fighting to clean the lake. But when the levee broke, she picked the city over the lake.
Ms. ANN REAMS: I mean, I'm from here. I'm from New Orleans, and I love this lake like a child. And as much as I love this lake, immediately I knew we had to pump that water into the lake.
SHOGREN: For weeks now, the floodwaters have been streaming into Lake Pontchartrain. They're full of sewage, garbage, oil products and who knows what else. Dennis Demchuk(ph) from the US Geological Survey is investigating the damage.
(Soundbite of water)
SHOGREN: Demchuk lowers a flat-bottom boat onto Lake Pontchartrain.
(Soundbite of boat motor)
SHOGREN: He and a colleague head out to test the stream of polluted water. Rita's on the way, and the water is so choppy that the small boat rises on the waves and slams down in the troughs. We're about a half mile from shore, where floodwaters flow into the lake, carrying all kinds of trash.
Mr. DENNIS DEMCHUK (US Geological Survey): Plastic bottles, candy wrappers. There's all that good stuff floating by. Some indeterminate--hey, I don't want to know what that one is, the brown one.
SHOGREN: A week ago, when he started sampling, he imagined finding bacteria levels in the millions.
Mr. DEMCHUK: So we were prepared for the worst.
SHOGREN: In fact, in samples Demchuk took a week ago, bacteria levels in the plume were four times higher than water quality standards for swimming, still much better than he feared. But the plume covers only a small area of the lake, and elsewhere, water quality is pretty good.
Mr. DEMCHUK: In the worst places, the concentrations were a couple of thousand last week, which is not good, but it is not the massive public health and aquatic life disaster that we were prepared for.
SHOGREN: Demchuk says there are many things working in Pontchartrain's favor. Perhaps the most important is the lake is huge, 24 miles wide and 36 miles long. The floodwaters made up less than 10 percent of its volume. One reason the bacteria isn't higher is that the water sat in New Orleans. Demchuk says the city became a retention pool.
Mr. DEMCHUK: It's not the way you'd want to treat sewage, but there's nothing like having a retention pond to reduce bacteria, because human waste bacteria needs to be inside of a human--of a warm-blooded animal to live, to grow. And so once they're out in the environment, they either stop reproducing or they start dying.
SHOGREN: Bacteria wasn't the only concern, but so far, tests haven't shown dangerous levels of toxic chemicals like oil products, pesticides or heavy metals. Also, the lake isn't a lake at all, but a bay connected to the Gulf of Mexico. Over time, the contaminates will be flushed out into the Gulf.
Mr. DEMCHUK: Those contaminates are not going to kill this lake.
SHOGREN: Hurricane Rita could present a mixed blessing. One levee in New Orleans has already overflowed, so there will be even more polluted water to pump into the lake, but the storm also may help remedy a problem Katrina left behind. Trees, leaves and other natural debris from Katrina pumped extra nutrients into the water. That caused algae to flourish. This can rob the lake of oxygen and choke fish.
Mr. DEMCHUK: Conditions like we're experiencing right now with this wind from Hurricane Rita, with this mixing and churning and wave action, that's going to churn it up enough that you probably won't get alga bloom at all.
SHOGREN: Demchuk and Pontchartrain's many other advocates believe that given time, the lake will recover. It's done so before when the odds were much greater. Elizabeth Shogren, NPR News.
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