Metals are the most frequently identified pollutant in rivers and lakes.
High nutrient concentrations also degrade many lake acres. Agriculture and mining are the leading sources of pollution in rivers. Agriculture, construction, urban runoff, and municipal sewage treatment plants are the leading sources of pollution in lakes. Ground water quality in Colorado ranges from excellent in mountain areas where snow fall is heavy, to poor in alluvial aquifers of major rivers. Naturally occurring soluble minerals along with human activities are responsible for significant degradation of some aquifers.