Toxicity of the lotic water bodies in the Silverton Caldera concerning the ability to support Hexagenia limbata, the giant mayfly
Evan R. Tweedie
Preface / Disclaimer
It is worth mentioning that this is a science fair project I did when I was 14 years old, so it isn't nearly as developed as the projects I am working on now. In 2020, this project placed 4th in the earth and environmental sciences senior division category at the San Juan Basin Region Science Fair in Durango, Colorado, then got an honorable mention at the 65th Annual Colorado State Science Fair (held online). Additionally, it won the Office of Naval Research Naval Science Award and NASA Earth System Science Project Award at the San Juan Basin Regional Science Fair, then won the Water Environment Federation Stockholm Junior Water Prize Award at the Colorado State Science Fair. The full report is available for download here:
Abstract
After I experienced the effects of the Gold King Mine wastewater spill in 2015, I asked the question: which creeks in the Animas River’s watershed could lead to its toxicity? I did a previous science fair project where I discovered that the creeks near Silverton were the most toxic.
My science fair project this year is on the toxicity of the lotic water bodies in the Silverton Caldera concerning the ability to support Hexagenia limbata, the giant mayfly. In this project, I retrieved water samples from various creeks and rivers before they reached the Animas River. I tested them for their pH, total dissolved solids, turbidity, and dissolved oxygen. I also exposed Hexagenia limbata, the giant mayfly to each of these sources and recorded their mortality.
My results showed that Cement Creek and Mineral Creek were the most toxic. They had the highest TDS, lowest pH, and the highest turbidity. These two creeks also had the highest mortality rate in Hexagenia limbata populations. Dissolved oxygen did not play a very large factor. Cement Creek and Mineral Creek were the most toxic lotic water bodies and they also had some of the highest concentrations of mine water flowing into them. This helped support my hypothesis. Not only did Cement Creek have the highest toxicity and the concentration of mines in its watershed, it also was the headwaters of the Gold King Mine Spill in 2015.