The Maroon Bells Recreation area is surrounded by Maroon Creek, which feeds into Crater Lake and Maroon Lake.
These natural freshwater ecosystems fill from snowmelt from the surrounding peaks and precipitation, and are major sources of water for the city of Aspen,CO.
According to the study  Environmental Impacts of Tourism on Lakes, water pollution can occur through indirect and direct methods.
Direct pollution to these natural bodies of water occurs when visitors choose to wade or throw items into these bodies of water, disrupting the fragile biodiversity.
An increase in human-traffic,such as the increase in the number of visitors who drive up Maroon Creek Road, is an example of indirect pollution.
This constant vehicular traffic releases pollutants such as nitrogen and sulfur dioxide into the water and air.

                                             
U.S. Forest Service officials were concerned about the high nitrogen compound levels in the waters at the Maroon Bells in 2003.
Officials mentioned that the increase in population and recreation in Colorado as well as an increase in the number of vehicles could be a cause of the elevated nitrogen compound levels, as these sources emit pollutants.
When precipitation forms over peaks like the Maroon Bells, these pollutants fall back to the Earth's surface and can travel into the river and lakes, harming fish, insects, and plants, particularly because of high levels of nitrogen.
The U.S. Environmental Protection Agency further supports the relationship between pollutants and their negative impacts on lakes, streams, and rivers.
The Maroon Bells Recreation area is surrounded by Maroon Creek, which feeds into Crater Lake and Maroon Lake. These natural freshwater ecosystems fill from snowmelt from the surrounding peaks and precipitation, and are major sources of water for the city of Aspen,CO. According to the study  Environmental Impacts of Tourism on Lakes, water pollution can occur through indirect and direct methods. Direct pollution to these natural bodies of water occurs when visitors choose to wade or throw items into these bodies of water, disrupting the fragile biodiversity. An increase in human-traffic,such as the increase in the number of visitors who drive up Maroon Creek Road, is an example of indirect pollution. This constant vehicular traffic releases pollutants such as nitrogen and sulfur dioxide into the water and air. 
                                             
U.S. Forest Service officials were concerned about the high nitrogen compound levels in the waters at the Maroon Bells in 2003. Officials mentioned that the increase in population and recreation in Colorado as well as an increase in the number of vehicles could be a cause of the elevated nitrogen compound levels, as these sources emit pollutants. When precipitation forms over peaks like the Maroon Bells, these pollutants fall back to the Earth's surface and can travel into the river and lakes, harming fish, insects, and plants, particularly because of high levels of nitrogen. The U.S. Environmental Protection Agency further supports the relationship between pollutants and their negative impacts on lakes, streams, and rivers.
Maroon Bells