A foreign invasive species is spreading to new areas. It’s a snail that could spread in huge numbers and compete with fish for food. The GLRC’s Mike Simonson reports:
A foreign invasive species is spreading to new areas. It’s a snail that could
spread in huge numbers and compete with fish for food. The GLRC’s Mike
The New Zealand Mudsnail has made its way to Lake Superior. It had already
been identified in Lake Ontario. These snails become dense on a river or lake
bottom. Minnesota Seagrant Aquatic Species expert Doug Jensen says it’s like
having half a million in the space of a bathtub. They can squeeze out bottom
dwelling organisms that fish eat. Jensen says native fish eat New Zealand
Mudsnails, but the fish don’t digest them:
“They can pass through the guts of fish and potentially waterfowl and then
survive that situation and then breed in a new location, where ever they’re
deposited. They reproduce asexually. They produce clones of themselves; they
don’t need a male to establish a new colony.”
The snails are the latest on a long list of invasive species that have likely been
carried in by foreign ships.
The Alcoa/Reynolds Company removes PCBs they once dumped into the St. Lawrence River. Photo by David Sommerstein.
Polluted sediments sit at the bottom of rivers and lakes across the Great Lakes region. They can affect water quality, wildlife and human health. More than 40 highly contaminated areas in the region have been identified by the EPA’s Great Lakes Office, but so far only about half of those sites have been cleaned up. This fall, dredging is taking place in at least three of those hot spots – all on rivers. The Great Lakes Radio Consortium’s Karen Kelly reports on the challenges of cleaning up a river bottom:
Polluted sediments sit at the bottom of rivers and lakes across the Great Lakes region. They can affect water quality, wildlife and human health. More than 40 highly contaminated areas in the region have been identified by the EPA’s Great Lakes Office.
But so far, only about half of those sites have been cleaned up. This fall, dredging is taking place in at least three of those hot spots, all on rivers. The Great Lakes Radio Consortium’s Karen Kelly reports on the challenges of cleaning up a river bottom.
(Sound of dredging)
Geologist Dino Zack stands on the steps of a mobile home overlooking the St. Lawrence River. He watches as barges glide in and out of an area contained by a 38 hundred foot long steel wall. Each barge carries a crane that periodically drops a bucket into the river bottom, pulling up sediment contaminated with PCBs. The goal is to remove 80 thousand cubic yards of contaminated sediment. Zack’s trailer is the EPA headquarters for the dredging project. He’s an independent contractor working for the federal government, which is spearheading the operation. And he’ll spend the next couple of months watching the Alcoa-Reynolds Company remove the chemicals they once dumped in the river.
“I’ll observe them while they’re collecting their data to make sure they’re following the work plan. Then, I’ll bring all the data back, assemble it into tables and review it.”
Zack isn’t the only one keeping a close eye on the dredging project, which began in June.
There’s another EPA scientist here, as well as two members of the Army Corps of Engineers who are supervising the work. There’s also a representative from the St. Regis Mohawk reservation, which is downriver from the contaminated area.
The EPA ordered Alcoa-Reynolds to clean up the pollution in 1993. The PCBs were present in a flame retardant liquid the company used in its aluminum smelting process.
Over the years, the liquid drained into the river, contaminating sediments along the shoreline. The most polluted area contains 2000 parts per million of PCBs. That equals about one bad apple in a barrel-full. The goal is to leave only one part per million of PCBs in the sediment. Anne Kelly is the EPA’s project director for the site.
She says achieving that level in a river environment is a challenge.
“One of the biggest problems with dredging a river is that you’re working without really seeing where you’re working. The other problem is the issue of re-suspension, that whenever this bucket hits the sediments, it stirs up sediments and then it settles out again.”
One of the biggest concerns is that the disturbed sediments will move downstream.
In this case, they’d only have to travel a mile to reach the drinking water intake for the St. Regis Mohawk reservation. That means toxins could make it into the drinking water.
Local people have also expressed fears that the PCBs could contaminate the air as well.
The dredging project was temporarily suspended this summer when residents on nearby Cornwall Island complained of respiratory problems. But air quality tests found the dredging wasn’t to blame. Ken Jock is the tribe’s environmental director.
He says in addition to air and water quality concerns, the local people would like to see a healthier fish population. Some species have been contaminated with PCBs. And he says that’s why the tribe supports the dredging.
“We know the PCBs will be there in a thousand years and we’ll be here, and we’ll still want to eat the fish. So we think that any solution has to be a permanent solution.”
The Alcoa-Reynolds Company had wanted to place a gravel cap over the chemicals rather than dredge. But the EPA ordered them to remove the PCBs. Rick Esterline, the company’s project director, says they’re fully cooperating with the government.
“You’re required to clean it up, that’s the rules and regulations that we have in our country. Whether they come at you with court orders or whether you do it, it’s still you have to do it.”
The project is expected to cost the company 40 million dollars. That includes the eight million dollar reinforced steel wall around the contaminated area. Alcoa-Reynolds is also using a special electronic bucket to remove the sediment. The EPA’s Anne Kelly says this has become the bucket of choice for Great Lakes dredging projects.
“Based on the information that will be transferred to the operator on the barge, he’ll know if that bucket is completely sealed, which is very helpful because a clamshell bucket will begin to close and hit a rock… he won’t know it’s still open partially and begin to pull that up through the water column with materials basically pouring out of it.”
Kelly says every cleanup project requires a different approach. In Michigan, General Motors is using an environmental bucket and silt curtains to dredge the Saginaw River.
Engineers in Michigan’s Pine River built a steel wall and emptied out the water inside before dredging. The dredging in the St. Lawrence is expected to finish in November.
And it’s possible it won’t reduce the PCB levels to one part per million. The cleanup at the nearby General Motors plant fell short of that goal. If that happens, the EPA will require the company to cap the river bottom – and monitor the sediments, the water and the fish indefinitely. For the Great Lakes Radio Consortium, I’m Karen Kelly.