Investment in wastewater treatment paying off
12:54 am
Mon April 14, 2014

Conn. & New York achieving nitrogen reductions in Long Island Sound

A report card released today by an environmental group gives Connecticut and New York pretty good grades for their efforts to reduce the amount of nitrogen pumped into Long Island Sound. The states have been working for a decade to reduce emissions of nitrogen coming from wastewater. Environmentalists say there’s still more to do.

Last August, just above the muddy floor of Long Island Sound, a flounder swam as fast as it could, trying to get out of the western Sound. Swimming along were blackfish, fluke and others. Below, crabs scurried over rocks, headed in the same direction. The clams had nowhere to go. Once again, there wasn’t enough oxygen for them to breathe. This was hypoxia.

Here's an animation of a map illustrating how hypoxia spread last summer.

Above them, in another world on the surface of the Sound and a little further east, was a 50-foot research boat, the John Dempsey. Its crew was trying to figure out just how bad it was for the creatures below. On the deck, a giant spool turned, uncoiling a line and lowering a scientific sensor off the stern. Matthew Lyman, an environmental analyst with the Connecticut Department of Energy and Environmental Protection, said this is one of 14 spots in the Sound they’ll test on this day.

“At each station what we do is take a profile of the water column and we get dissolved oxygen readings from the surface all the way to the bottom," said Lyman. "And we’ll be able to see that data real time.”

So-called “dead zones” have been recorded in the Western Sound every summer for decades.   On this day, the researchers are trying to find eastern edge of hypoxic zone. Environmental analyst Katie O’Brien Clayton, watched a laptop and read the data from the submerged sensor as it sank deeper into Smithtown Bay.  Anything at 3 milligrams per liter of dissolved oxygen or lower is considered hypoxia.

"Bottom!" called out O'Brien Clayton. "So we end up at 2.94”

It’s a disappointing result for Lyman. When they were here a few weeks ago, there wasn’t an oxygen problem.

“I was hoping that that would have continued and stayed more to the west, but it appears it’s moved further eastward,” he said.

For years, hypoxia conditions between Westchester and Nassau Counties have been considered moderately severe, and moderate hypoxia patches have been recorded as far east as Bridgeport. The problem comes from too much nitrogen in the water.  Just like it does on a lawn, nitrogen promotes growth in the Sound. In the water, that means more algae, which then dies and sinks to the bottom, where it’s eaten by bacteria. And while they’re eating up that algae, the bacteria use up the oxygen at the bottom. So the way to stop that chain reaction from happening is to cut out the nitrogen that’s kicking it off.

In 2004, Connecticut and New York agreed to reduce the nitrogen going into the sound by 58.5 percent by this year. And they did that by going after the biggest source - wastewater treatment plants.

At a wastewater treatment plant in New Haven, a grey waterfall pours into an open tank at a plant in New Haven. It doesn’t smell so great.

A tank of effluent and nitrogen-breathing bacteria in New Haven
Credit Craig LeMoult

“This grey water coming in, this is called primary effluent,” said  Gary Zrelak, the director of operations for the Greater New Haven Water Pollution Control Authority. He pointed to a couple tanks holding 10.6 million gallons of brown liquid. Zrelak said the brown isn’t what you might think. The color comes from bacteria. In the first tank they have oxygen pumped in to breathe. Then the effluent goes into a second tank.

“So these bacteria have all the food they want, they’re trying to consume it, but there’s no oxygen for them to breath.”

The bacteria in this tank have a special power – if there’s no oxygen, they can breathe nitrogen.

“And hence, we’ve just removed nitrogen from the water column,” said Zrelak.

By the time it’s pumped out into the sound, they’ve cut more than half of the nitrogen, and the water looks pretty clear. These tanks full of nitrogen breathing bacteria have been added to wastewater treatment plants on both coasts of the Sound, and more are being built. A report card released Monday by the environmental group Save the Sound says a decade after committing to a 58.5 percent nitrogen reduction, Connecticut has reached its goal. And while New York isn’t quite there yet, they got a respectable grade.

“The good news is that everybody gets and A or B. From an environmental group, those are really good grades,” said Curt Johnson, executive director of Save the Sound.

Here's an interactive map from Save the Sound, illustrating levels of nitrogen discharged by wastewater treatment plants in New York.

New York  managed to get an extension to meet their goal – the counties, which are responsible for the improvements,  have until 2017 to get there. In New York state alone the projects will cost about 2 billion dollars. So far, they’ve made the necessary improvements to their wastewater plants on Long Island and New York City should be done this year.  In Westchester, they want to see how improvements to two plants do for a year before they start on a third.

“So that’s why we consider them in the terms that teachers use as sort of an at-risk student, said Johnson. "We have to watch. We have to carefully make sure that they do make those upgrades.”

Jim Tierney with the New York Department of Environmental Conservation said they’ll meet their deadline.

“Doesn’t mean our work is over. It means a very ambitious construction and water quality program that was started back in 2004 is finished within a decade. And I don’t know anybody else in the country who has done anything comparable.”

It looks like it could be one of those rare success stories – when environmental advocates and state governments will be able to say they actually achieved what they set out to do. But it will take some time to see the impact of the nitrogen reduction. And there are still issues to address. Leaky sewer pipes and storm water runoff continue to be serious problems. And as for wastewater plants, the environmentalists are now looking further up the rivers to Massachusetts, where they don’t have huge tanks of hungry bacteria, and where they’re sending nitrogen down three rivers, and into Long Island Sound.