The Alamosa and Conejos rivers are two rivers in Southcentral Colorado that are approximately 3.5 km apart at their closest point, but do not connect at any point. The Alamosa River was affected by the Summitville mine disaster in 1991. The Alamosa River was declared a Superfund site in 1994 and clean-up of the Summitville Mining Site and surrounding watershed continued for 27 years.
This study aimed to determine whether recolonization of aquatic invertebrates in the Alamosa River has occurred after the clean-up activities in the Alamosa River watershed. I collected aquatic insects each week for 10 weeks using sweep netting and bottle-trapping. I also determined water quality of both rivers by measuring pH, nitrates, ammonia, dissolved oxygen, and sulfates. The results indicated that pH, nitrates, dissolved oxygen and sulfates were not significantly different in the two rivers, but ammonia levels were significantly higher in the Alamosa river. The biodiversity of the Conejos River, however, was much higher than the Alamosa River, with an abundance of Ephemeroptera, Trichoptera, Diptera and Plecoptera. The Alamosa river biodiversity was nearly zero, with only 5 Ephemeroptera and 2 Dipteran collected for the entire season. Despite the massive cleanup of the Summitville Mining site, the effects of the mining disaster still affect aquatic life nearly 30 years later.