By USEPA Environmental-Protection-Agency. Public domain, via Wikimedia Commons

It’s been more than a year since the Gold King Mine in Colorado poured heavy metals and other contaminants into the nearby Animas River. The polluted waters turned the river a mustard yellow and forced people living downriver to find other water sources until the river cleared.

The U.S. Environmental Protection Agency (EPA) recently released its final report on the spill. Approximately three million gallons of contaminated water was released into the river in August 2015 when a contractor working with the EPA preparing the mine for cleanup caused the spill.

Earlier estimates tallied the amount of metals in the river system at 440 tons. However, analysts determined the actual amount was 540 tons. The pollution, most of it iron and aluminum, went swiftly down the river system and ended up in rivers in New Mexico, as well as Utah.

The spill brought to the forefront the need to safely clean up abandoned mines throughout the western part of the country. There are 161,000 abandoned mines, and 33,000 of those are affecting the environment with their leakage.

The spill caused problems for the Navajo Nation, located along the San Juan River, a tributary of the Animas River. The banks of the river are home to thousands of farmers who lost crops and were forced to bring in their own water until the river was deemed ready for use by the EPA.

While the EPA has said the river system has returned to pre-spill levels of water quality, the Navajo Nation and environmentalists are concerned that the heavy metals that have since settled on the floor of the river could be sent downstream again due to a heavy rain or melting snow. It’s a concern that has been echoed with the Emory River after the Kingston Fossil Plant, operated by the Tennessee Valley Authority, experienced a dike failure that sent 5.4 million cubic yards of coal ash into the river. Today there are still worries about the effects the remaining coal ash at the bottom of the river will have on the environment.

A year after the spill, the Navajo Nation filed a lawsuit against the EPA, alleging the agency did not notify the Nation early enough, and that the EPA should pay $160 million in damages as well as pay for cleanup costs the Navajo incurred that have not been reimbursed by other groups.

In a statement, the EPA said “[it] will continue to work with states and tribes to ensure the protection of public health and the environment in the river system affected by the Gold King Mine release.”