The glum folks who insist that government control of all natural resources is necessary to save the planet, who regard nature as defenseless and doomed, ought to click here for hope. New research by the U.S. Geological Survey documents the dramatic revival of a 50-mile stretch of the Potomac River that was once considered “decimated” and “barren.” The case demonstrates once again that government is not the ultimate environmental steward and that nature is resilient enough to forgive our mistakes.

Decades of discharges from government-run wastewater treatment plants—particularly Washington, D.C.’s Blue Plains facility—loaded the Potomac with nitrogen and other nutrients that nurtured colonies of algae. In conjunction with sediment from runoff, the algae clouded the water and blocked sunlight from reaching riverbed vegetation—the source of oxygen, food, and shelter for invertebrates, fish, and waterfowl. A dark emptiness thus descended, prompting President Lyndon B. Johnson to declare the river “a national disgrace,” according to The Washington Post.

Similar problems plagued waterways across the country; the U.S. Environmental Protection Agency concluded that publicly owned wastewater treatment facilities presented a “significant” risk to water quality. However, the advent of technology capable of filtering nutrients from wastewater discharges has allowed nature to revive itself.

According to researchers, aquatic vegetation is flourishing in the Potomac once again. Since 1990, in fact, the area covered by native vegetation has increased more than tenfold, from 288 acres to 3,081 acres. And as the presence of native species has increased, the proportion of “invasive” (non-native) species has declined.

As noted by the researchers: “Species composition was significantly correlated to the relative dominance of natives. When nitrogen loads decreased, species composition shifted such that natives became more dominant and diversity, evenness, and total SAV [submerged aquatic vegetation] abundance increased.”

This comes as particularly good news given the oft-repeated predictions that invasive species pose an insurmountable threat to lakes and rivers. And while challenges remain—the Potomac is hardly pristine—the return of native vegetation is a most welcome milestone in the river’s renewal. Eco-alarmists can take solace from the fact that nature can overcome even major environmental missteps by humans.