Rivers are changeable. Some are clear, like the Concord River travelled by Henry David Thoreau. Others, like the Mississippi, are turbid and “charged with hidden meaning” (3). And some flow backwards through human intervention. The Chicago River was the destination for all of Chicago’s waste prior to the construction of the Chicago Sanitary and Ship Canal, which forced the river to change directions. This meant that waste no longer flowed into Lake Michigan—the city’s source of drinking water—and was the largest public-works project of the early 20th century.

Humanity’s impact on the planet has become so significant that the only way forward is not to reverse that impact, but to manage its consequences: “the new effort begins with a planet remade and spirals back on itself—not so much the control of nature as the control of the control of nature” (8).

Now, the Chicago River is the site of a project by the United States Army Corps of Engineers, which is pulsing electricity into the Sanitary and Ship Canal to stop fish without blocking the movement of ships. The measure is trying to prevent Asian carp, a voracious invasive predator, from moving into Lake Michigan and the other Great Lakes. Asian carp, four distinct fish species native to China that are declining in the wild there, introduced to America by the US Fish and Wildlife Service as a biological control measure for another invasive species.