Around this time last year, I was walking the banks of the Animas River in Durango, the southwestern Colorado town blindsided last week when the river turned a sickly yellow-orange from a colossal spill of toxic mine drainage upstream near Silverton.

It’s hard to imagine a river more central to a town than the Animas is to Durango. Bikers, runners, and dog-walkers keep both banks in constant motion, as endless flotillas of tubers and rafters float the river through town.

Twice I hiked the Animas Mountain trail, which affords spectacular views of the river’s meanders and oxbows, and of the riverside town of 17,000 below. From on high, the Animas seems to knit the landscape of forest, farm and town together. If ever a river was the lifeblood of a community, it’s the Animas flowing through Durango.

So when I heard the news of the breach at Gold King Mine that sent massive quantities – ultimately some 3 million gallons – of drainage laced with toxic metals into the river, my heart seized up and my mind raced ahead. Not the Animas. How could this be? And how far will that frightfully colored plume of pollution go?

The tragic accident occurred as contractors for the Environmental Protection Agency (EPA) were working to plug Gold King, which had been leaking acid mine drainage into the river system for years.

But the stage was set by decades of neglect and the near-absence of any requirements that mining companies take responsibility for preventing harm to people and aquatic life after they close their mines. Some 500,000 abandoned mines, most un-reclaimed, now dot the nation’s landscape.

And as we’ve learned from the Gold Kind tragedy, we all live downstream.

As the toxic waters spewed out of Gold King, they entered Cement Creek, which quickly carried them into the Animas. The Animas then transported the plume south to Durango, then through Southern Ute Tribe territory, and on down to the northwestern New Mexico town of Farmington, where the Animas joins the San Juan. The San Juan then takes the pollution westward through Navajo country, before entering the east branch of Lake Powell, the massive storage reservoir on the Colorado River just upstream from the Grand Canyon.

Virtually the entire stretch of the San Juan from Farmington to Lake Powell is designated endangered species habitat for two of the four endangered native fish species in the Colorado Basin, the Razorback Sucker (Xyrauchen Texanus) and the Colorado Pikeminnow (Ptychocheilus Lucius).

The hurt and harm have moved right along downstream with the contaminated waters.

In Durango, the river is closed for business until further notice. The Southern Ute Tribe declared a state of local disaster. Several towns in New Mexico stopped pumping river water into drinking water systems. And the Navajo Nation plans to sue the EPA, after estimating that the spill has affected more than 100,000 Navajo people who live and farm along the contaminated San Juan.

“The spill has impacted us religiously, emotionally, financially,” the nation’s president, Russell Begaye, told TIME magazine this week.

On Thursday, August 13, eight days after the toxic release, environmental officials in Utah said that while the plume is no longer visible, hydrology and water-speed calculations suggest that the contaminated waters had reached Lake Powell, some 300 miles downstream from the Gold King Mine.

The full ramifications of the spill will obviously take time to uncover and assess. EPA’s early testing of the Animas turned up high levels of arsenic, copper, lead, molybdenum and other contaminants. Levels of lead exceeded federal standards for human drinking water by some 3,800 times.

Although EPA says water quality returned to pre-spill levels once the plume passed through the area, testing and cleanup of riverbed contamination and related impacts are yet to come.

It will take many years and millions of dollars to remediate Gold King Mine and the tragedy it unleashed.

Meanwhile, it is critical to take action now to prevent other spills from happening. As I write, thousands of abandoned mines are leaking acid drainage into streams, just as Gold King had been doing before last week’s spill.

It’s long past time to stop pushing mine pollution off on future generations. The 1872 Mining Law, signed by Ulysses S. Grant, is one of the most antiquated and environmentally destructive laws on the books. It requires no royalty payments from mining companies, minimal protective actions while the mine is operating, and virtually no cleanup and restoration after a mine is closed.

Its principal legacy, the New York Times wrote this week, “is a battered landscape of abandoned mines and poisoned streams.”

EPA estimates it would cost $20-54 billion to clean up the abandoned mines (not counting coal mines) nationwide.

A good place to start would be to make mining companies pay to mitigate the hazards left from past operations, as well as to strengthen regulations on new mines to avoid the creation of new threats.

Until the mining laws are reformed and the abandoned mines get cleaned up, more disasters like Gold King are bound to happen.

And we all live downstream.

Originally posted at National Geographic Newswatch.