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The Water Intake Crib: A Primer

The views expressed are those of the author and are not necessarily those of Scientific American.


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So Toledo and environs goes through a terrible water crisis when nutrient-rich water from farms, lawns, and other nonpoint sources flows into Lake Erie. This causes hideous algae blooms that turn whole portions of Lake Erie a frightening bright green. Nasty enough, but the algae also release a toxin, microcystin, that can make you seriously sick.

Image: WKYC

The water treatment plant can do things like remove the algae themselves, and it can handle a little bit of the microcystin, though a lot of it pretty much overwhelmed the treatment plant, which is why the people of the region had to drink water out of jugs or shiny metal trucks. You can’t boil it, because the microcystin isn’t a bacteria, it’s just a nasty chemical — so boiling, paradoxically, just increases the concentration of the nasty.

Certainly, we should all be working to reduce the flow of pollutants from our farms and lawns that cause such things — they’re the leading cause of water pollution in the nation. We did such a good job cleaning up our waterways when we addressed point source pollution like factories that if we put our mind to it we can address this too — we’ll end up with better farming practices and better food, too.

But enough of that. I want to talk about water cribs.

You’ve heard the phrase “water crib” in several of the stories about the problem, which exists because the the algae bloom occurred right around the intake for Toledo’s water treatment system — the water crib, as it’s called. And the reason the ban has been lifted is because, quite simply, the wind blew the algae bloom somewhere else. But if you’re lucky, you’ve seen pictures of Toledo’s water crib.

It’s a completely cool thing, created when a caisson is built on land, towed out to sea — in Toledo’s case, about 2.5 miles — and placed on the bottom. The water is pumped out, and then engineers drill a tunnel from the bottom towards shore, meeting with a tunnel started from shore. (That tunnel-meeting-tunnel thing at exactly the right place, by the way, is miraculous — and bear in mind people have been doing it since the sixth century BCE.) I’ve been unable to find out when Toledo’s crib was built, but there are similar cribs offshore of Chicago, Cleveland, and Buffalo, and they all tell the same story: A muscular culture building vast systems to sustain its members.They tell other stories too, of course — Chicago built a new crib further out into Lake Michigan when its own pollution fouled the water near its crib, then eventually just turned around the river so it flowed into the Mississippi River basin and became St. Louis’s problem. St. Louis eventually sued. Long story.

Image: Geocaching.com

Most cribs have lighthouses, and most used to be crewed, though nowadays they’re just monitored by the usual spate of motion-detectors and cameras.

We don’t much build things like that these days — we don’t like to pay for them, however much we obviously need them. So I just thought it was worth bringing up those cribs. It’s nice that the wind blew away the blue-green algae, and I’m certainly glad people of Northwest Ohio and Southeast Michigan can drink their water again. But it’s always worth reminding ourselves of the systems that bring us that water — and what we can do if we set our minds to it.

Scott Huler About the Author: A writer who commonly explores science, culture, and the relationship between the two. Follow on Twitter @huler.

The views expressed are those of the author and are not necessarily those of Scientific American.





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