We better give a carp about invasive Asian fish hitting Great Lakes, but must we poison the water?

So it's come to this: we have to poison our waterways to protect our waterways.

Yes, in a development that brings to mind that (possibly apocryphal) saying about a Vietnamese village in the 1960s, it seems that the state of Illinois has agreed to try to keep the invasive Asian carp out of the Great Lakes by poisoning Chicago-area waterways every time locks are opened to let boats through to Lake Michigan.

The Obama administration this week rolled out a $78 million plan to fight the carp and sought to broker a deal between the governors of Illinois, Michigan and Wisconsin, as well as federal agencies involved. Illinois wants waterborne commerce to continue, as do shippers, represented by the American Waterways Operators.

Michigan and Wisconsin are terrified that the carp will crowd out Great Lakes native fish -- just as they've done in the Illinois and Mississippi and Lower Missouri rivers, pummeling fisheries that formerly targeted much-more-valuable native fish.

Now, it's a pretty scary prospect that this aggressive Asian carp seems likely to blow past humans' efforts to keep it out of the Great Lakes. That could spell disaster for the native fish living off of America's  "northern coast." And carp DNA -- probably from their poop -- already has been found right at the edge of Lake Michigan.

The fish -- several species, actually -- were brought into this country to control nuisance algae, apparently, but got loose in waterways connected to  the Mississippi River. They've worked their way up the basin.

The U.S. Army Corps of Engineers thought it had controlled their spread into the Great Lakes by setting up an elaborate fish-electrocution system about 20 miles downstream from Lake Michigan.

But late last year came news that highly sensitive DNA tests pinpointed some of the carp much closer to Lake Michigan that previously thought -- right where several waterways empty into the lake. Now, it's possible that poop was carried far downstream, and the fish aren't about to enter the lake -- but that's a stretch.

It seems the plan to keep them from coming from their now-established home into Lake Michigan rests on a 25-point plan hammered out with the aid of U.S. Environmental Protection Agency chief Lisa Jackson and Nancy Sutley, head of the White House Council on Environmental Quality. As Kari Lydersen explains for OnEarth magazine's Green Light blog, the new plan means that within 90 days:

... the locks will be opened less frequently, and whenever they are, the waterways would be poisoned and other control measure(s) instituted to make sure the carp don't progress past their current territory.

Lydersen goes on to explain that there are still arguments about whether, in fact, the fish have gotten past the Electrocute-A-Fish Machine built by the Corps downstream.

Is poison really necessary? Maybe so. But there is one other fascinating possibility about how to cut out the carp: U.S. Geological Survey researchers are looking into the possibility that pheremones harvested from carp skin could be used to repel the invasive fish. I'm speculating a little here based on what I know to be true of salmon, but apparently there's something about a skin pheremone released into the water that screams to other fish nearby:  "Predators!" USGS has some other thoughts about more-natural ways to keep the carp out of the water.

-- Robert McClure