One of America's most iconic engineering marvels is being threatened by an advancing army. This is not a military threat---though it is foreign. 

Quagga and zebra mussels, the twin scourges of the Great Lakes are marching west...well, actually hitchhiking. 

The invasive species that have wreaked havoc and literally reshaped the ecosystem of Lake Michigan have a sneaky history. They originally arrived as stowaways in the ballast tanks of ocean-going tankers in the 80s and 90s. Introduced into a new freshwater ecosystem, they flourished and became the most numerous life forms in the Lake, having long ago pushed out the native species. 

And now, they seem to have pulled off the neat trick of stowing away on smaller boats that have unwittingly transferred the malignant mussels into the waters of the West. Dan Egan's excellent article in last weekend's Milwaukee Journal-Sentinel details the ugliness that followed when the stowaways departed from Midwestern pleasure boats in one of the West's most recognizable waterways:

If you drained Lake Mead above Hoover Dam, says National Park Service biologist Bryan Moore, it would reveal that brown canyon walls that were mussel-free just two years ago are now black with quaggas at densities of up to 55,000 per square meter.

Divers report them smothering everything on the lake bottom, from beer cans to a downed B-29 bomber. The rapacious, razor-sharp invaders are bloodying Lake Mead marina workers and are so thick in some places they've even sunk buoys.

As of last week, zebra and quagga mussels turned up in 33 bodies of water across Nevada, Arizona, California, Colorado and Utah.

And they're spreading into fresh waters.

Sinking buoys? Remember, most zebra mussels are the size of your pinkie finger nail!

Uh oh.

Here in the Midwest, we know what will follow. A rapid advance of the itty-bitty bivalves clogging water intake pipes. In cities like Chicago and Milwaukee, the annual toll has been in the neighborhood of $100 million to try to get control of the problem and keep water flowing.

In the parched western states, beyond the possibility of trashing Hoover Dam's essential water intake pipes (and the power for a half million people), the infrastructure for moving water is probably even more susceptible to attack:

Nobody can put an exact price tag on what all this will cost the West, but in his testimony to Congress last summer, Ric De Leon of the Metropolitan Water District of Southern California noted that the annual pipe-clogging cost for mussels in the Great Lakes is about $100 million.

He predicted costs in the West could exceed $250 million annually because of the extensive waterway networks lacing this dry side of the continent. He noted there are about 1,800 public water systems in the West drawing on surface water to serve 47.5 million people.

Yikes. This story makes it clear that we still need to get serious about the unglamorous world of ballast water law. On average, a new invasive species is introduced into the Great Lakes through the dumping of this water used to steady big boats.

There is good news on this front.

NRDC recently had a win in federal court protecting Michigan's tough ballast water rules. And we will soon be defending the State of New York's even tougher standards.

Just last week, the State of Wisconsin passed restrictions similar to the ones in New York.

And this week, Secretary Jackson announced that the federal EPA was now, thankfully, on the case.

But despite all this good news, the problem is not going away. Want a reason to care about this seemingly boring issue?

History shows that once an invasive species becomes established in the Great Lakes, it likely will never be eradicated. That doesn't mean the lakes - or the nation - have already seen everything the outside world can throw at them. The viral fish-killing disease known as VHS, for example, was not detected in the Great Lakes until 2005.

Fish ebola! Bleeding fish washing up on the shore. Who on Earth is fighting to keep that status quo? Well, among others, we have been fighting shipping interests in New York and Michigan:

Great Lakes oceangoing ships primarily haul steel and grain, and the whole enterprise is worth $55 million a year in terms of transportation savings, according to a 2005 Joyce Foundation-funded analysis of overseas cargo flows on the Great Lakes. In other words, it would cost the region that much more if overseas ships weren't allowed into the Great Lakes and their cargo were instead hauled by some other mode, such as truck, rail or Mississippi River barge.

Doesn't seem like a very good deal, huh? Saving $55 million in exchange for a problem that has already cost us billions...

But there are worse options still...

The problem is so scary, that some water managers are getting desperate and considering shockingly drastic measures.

Lorri Gray, regional director for the Bureau of Reclamation in Boulder City, Nev., meanwhile, worries about the ecological damage the mussels could do to dozens of native species already suffering from the dam construction projects during the past century.

She's thinking it might be a good idea to bring in some sterilized mussel-eating Asian carp.

Umm, that is a bad idea. A very, very, very bad idea that reminds me of that great kids song:

She swallowed the spider to catch the fly... I don't know why she swallowed the fly... Perhaps she'll die.

"Measuring Quagga Mussel Height" photo by Wendy S. Smith via Flickr