Tuesday, February 2, 2010

An Invasives Barrier for the Champlain Canal

Asian carp are all over the news and will soon be all over Lake Michigan unless the Chicago canal that links the Mississippi and Great Lakes watersheds is re-engineered. It’s looking unlikely, but if the Obama administration decides to turn this dilemma into a major public works project—keeping a particularly nasty invasive species from upending the remnants of native Great Lakes fish life—there’s a canal on Lake Champlain that could use a lift too.
The Champlain Canal is the single largest gateway for invasive species to Lake Champlain. Since it opened in 1823, at least a dozen kinds of nonnative plants and animals have passed through it, evidently including zebra mussel and water chestnut, which have made nuisances of themselves. The rate of invasives is accelerating: Asian clam is now two locks below the lake, quagga mussels are in the Hudson River, and round gobies and spiny waterflea have respectively reached the Erie Canal and Great Sacandaga Lake, all linked by water to the Champlain Canal.

The first rule of invasive species control is don’t let them in. Prevention is always cheaper and more effective than trying to manage or eradicate. A 2008 meeting of stakeholders on the lake, including the director of the New York State Canal Corporation, concluded that something should be done about the Champlain Canal. The group also agreed the solution must not impede boat traffic and should be effective against fish, plants, plankton and invertebrates and do minimal harm to native species. Chemical barriers can hurt untargeted species, and introducing animals to eat nuisance invasives can be tricky and too narrowly targeted.

The solution that seemed to meet most of the group’s goals was “hydrological separation,” for example, a closed and dry lock that interrupts water connectivity. Big Chute Marine Railway, in the Trent-Severn canal in Ontario, includes a boat lift to move vessels over a barrier. It keeps sea lamprey out of Lake Simcoe, and it’s a curiosity for tourists.

A boat lift would be costly and might seem a little crazy, but real crazy is to foster Asian, British and Baltic fish in weed-choked waters that once ran clear and so thick with salmon you could spear them in the tributaries with a pitchfork. No big U.S. lake is like Champlain anymore. Although partially impaired by 48 nonnative fish, aquatic plants, invertebrates and pathogens (see the list here), Champlain’s fishery so far has been spared the utter unrecognizability of the Great Lakes mainly because commercial ships no longer pass through; traffic in the Champlain and Chambly canals is mostly recreational. Lake Champlain still has 70 native fish species, including the passive mottled sculpin that has elsewhere been displaced by the aggressive round goby.

The above information is all from documents on the Internet; the Lake Champlain basin has a vigilant multistate aquatic invasives task force that is constantly investigating proactive strategies like heating the water in the Glens Falls Feeder Canal to stop spiny waterflea. But last we talked to a task force member, at the end of 2009, no plans for a barrier on the Champlain Canal were advancing through Congress or the Army Corps of Engineers. The awareness raised by the Chicago canal presents an opportunity. Lake Michigan might not stand a chance, but Lake Champlain still does.

Photograph of the Big Chute Marine Railway in Ontario

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Mary Thill

Mary Thill lives in Saranac Lake and has worked alternately in journalism and Adirondack conservation for three decades.




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