In August 2015, 3 million gallons of acid mine drainage flooded into Cement Creek, flowing into the Animas River and then the San Juan River. Downstream communities in Colorado, New Mexico and Utah watched in shock as the rivers they love, the rivers on which they depend, turned an unworldly orange color.
The iron oxides that gave the river its orange hue told a story many knew but seldom discussed. Our mineral-rich San Juan Mountains are a source of heavy metals including elements like iron, zinc, lead and arsenic, which flow with the water from mountain to desert communities across the Colorado Plateau. Because the mountains were mined for their mineral treasures, the flow of water and oxygen into the rock became elevated, increasing the movement of metals from the rock, to water, to us.
The plume in August 2015 was highly visible. The event occurred when the river’s flow was low, limiting dilution. However, heavy metals generally don’t let us know they are there. We know they are present when the river runs orange, but the color of the river does not necessarily tell us if it’s a health risk.
Iron is a common metal in many rivers, including the Animas. Oxidized iron, better known as rust, is what caused the river’s vibrant orange color during the Gold King Mine spill, and now the burnt orange color during spring runoff. Then and now, local officials from San Juan Basin Health are faced with providing human health-related information regarding a historical problem that’s been decades in the making. In partnership with Colorado Department of Public Health and Environment and the US Geological Survey with funding from the Environmental Protection Agency, their state-of-the-art monitoring efforts will provide insight on river color, water chemistry and health risk.
Two types of water chemistry data are being collected. First, sensors are in place in the river from Cement Creek to Durango to track the signatures of metals contamination such as the water’s cloudiness, acidity and the amount of dissolved solids. This real-time data will automatically trigger alerts to health officials based on the river’s chemistry, a better indicator of health risk than the striking visuals we can see. Citizens can sign up on La Plata County’s website to receive alerts when water quality changes.
Second, water and sediment samples are being collected from these locations for analysis of metals concentrations to indicate what is actually present in the river.
A rust-colored river is not all good or all bad. It is a sign that iron and other metals are present in the river, a result of the natural and human history of the region. Together, we can work to reduce the metal inputs that are a result of the human impacts, and the river will run less orange. However, until that work is complete, the river’s color may at times be orange. For a mountain river such as the Animas, which is known to have metals in it, this is a good sign. The orange color indicates the presence of undissolved metals, which are less harmful to human and aquatic life than dissolved metals.
Through a partnership between San Juan Basin Health and Fort Lewis College, time-lapse photos that show river color and flow, taken from the same locations as the sensors and river water and sediment data, will be made into videos.
The videos will enable us to understand the river in a new way. We will be able to see the river over the course of a day, each day of the year, in combination with the water chemistry data that can’t be seen when we stand at the river’s edge.
This innovative approach of visual and chemical monitoring, integrated with an alert system, may be the future of mountain river monitoring.
We live in the West and depend on water for our well-being, as does the intricate river ecosystem. These monitoring efforts help us understand our water resources and will increase the dependability of our water supply system and the resilience of our communities from mountains to deserts across the West.
Heidi Steltzer is a Fort Lewis College biology associate professor. She studies mountain watersheds and Arctic ecosystems, focusing on their responses to environmental change. Reach her at email@example.com. Sign up for Animas River Alerts though La Plata County’s CodeRED system at co.laplata.co.us.