On August 5, an Environmental Restoration company crew, supervised by US Environmental Protection Agency officials, used an excavator to dig away tons of rock and debris that were blocking the entrance portal of Colorado's Gold King Mine, which had been largely abandoned since 1923. Water had been seeping into the mine and out of its portal for decades, and the officials knew (or could and should have known) the water was acidic (pH 4.0-4.5), backed up far into the mine, and laced with heavy metals.
But they kept digging--until the greatly weakened dam burst open, unleashing a 3-million-gallon (or more) toxic flood that soon contaminated the Animas and San Juan Rivers, all the way to Lake Powell in Utah. To compound the disaster, EPA then waited an entire day before notifying downstream mayors, health officials, families, farmers, ranchers, fishermen and kayakers that the water they were drinking, using for crops and livestock, or paddling in was contaminated by lead, cadmium, mercury and arsenic.
