An Agrarian Aquarium-Turning Cities Into Farms

For years and years, Fridays in Milwaukee were also fry days. Seafood lovers and Catholics abstaining from meat feasted on yellow perch plucked from Lake Michigan. But decades of industrial pollution and overfishing jeopardized a beloved tradition.

Now the perch thrive in an unlikely atmosphere — a renovated downtown factory — and they have steady jobs fertilizing organically grown produce prized by local chefs.

Sweet Water Organics, founded in 2008, has had up to 80,000 fish at a time in its 100,000-square-foot facility, and produced up to 1,000 pounds of produce a month. The water the fish live in carries their waste to the roots of lettuce plants, which in turn filter the water. The process, called aquaponics, builds on the work of MacArthur Foundation “genius” fellow Will Allen — and it has the potential to transform the way cities sustain themselves.

"One of the big promises in aquaponics, one of the things that really attracted me to it," says Sweet Water vice president Todd Leech, "was the idea of containerizing these systems and putting them in disaster-stricken areas or drought-stricken areas or areas traditionally inhospitable to growing clean produce and good clean protein.

"The produce that you see coming out of these systems, that is fortified by the fish waste, is some of the best stuff that I've ever had," he continues. "What works really well for me in selling it — because I also act as a sales manager for Sweet Water — is it's incredibly hearty. A lot of restaurants take it in 2- or 3-pound bags, and they take multiple bags at a delivery, and the stuff — as long as it's sealed and refrigerated — it stays hearty. It doesn't turn into the brown goo that you see shipped all over from other growers."

Sweet Water, which is in the process of being certified organic, already employs only organic seed and natural cultivation methods.

"We don't use any chemical fertilizers or pesticides, anything like that," Leech says. "Any kind of pest management that we've done has been with basically three elements — water, ladybugs and praying mantises. If it's cheap seed, if it's grown as cheaply as possible, it's not going to be a great product. This is real good food. It shows that nature knows best."

And what Sweet Water Organics has learned from nature, its Sweet Water Foundation shares with students from kindergarten to graduate school, from Milwaukee to Chicago. Sweet Water's principal farmer, Matt Ray, maintains an aquaponic greenhouse at a local Montessori school with his students there. Leech says a "huge" digital learning program will use urban food production as a model for education in fields ranging from agriculture to engineering.

But the biggest change at Sweet Water is that its farming operation is moving outside the warehouse and into a greenhouse — and despite the frigid winter temperatures on the shore of Lake Michigan, it will operate year-round.

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