anthropogenic disturbances affect inland waters and their associated riparian ecosystems:

  • Livestock grazing contributes to increased inorganic sediments, nutrients, and organic matter; breakdown of stream banks; and removal of riparian vegetation.

  • Forestry and logging practices, including extensive road building, introduce sediments and logging slash; remove large woody debris; increase runoff and streambed scour; and erode stream banks.

  • Agricultural practices add sediments, nutrients, and toxicants; deplete streams through irrigation withdrawal; channelize streams; drain wetlands; and destroy riparian habitats. Pesticides applied to forest and agriculture lands often reach waterways.

  • Mining and smelting operations release heavy metals and other poisonous substances to water bodies via surface, subsurface, and aerial pathways.

  • Urban usage removes water for domestic consumption; adds sewage and many complex household and other chemicals; converts stream channels into concrete-lined gutters; and contributes fertilizers, herbicides, and pesticides.

  • Manufacturing and processing operations release chemicals and heated water and, along with motorized vehicles, contribute airborne pollutants that reach waterways.

  • Fish management practices use poisons to remove unwanted species and introduce exotic species.

  • Impoundment for flood control, electric power generation, navigation, and recreation drowns rivers, changes flow patterns, alters nutrient and sediment loads and temperatures, and thereby destroys the habitat and impedes or blocks the movement of native aquatic fauna.

  • Diking, channelization, and removal of woody debris for navigation, flow "enhancement," flood control, or fish passage all speed up the flow of water; destroy habitat; disrupt in-stream processing of organic matter and nutrients; and prevent interchange of nutrients, organic matter, and sediments within the riparian environment.

  • Production of electricity by coal-fired or nuclear reactor steam plants depletes water by evaporation and by diversion from natural water bodies and may increase temperature, trace elements, and other chemicals.

Nutrients from many of the above activities, particularly nitrogen and phosphorus, cause the accelerated enrichment (cultural eutrophication) of lakes and streams. This can result in large-scale fish kills and the elimination of desirable fish species, production of foul odors, uncontrolled growth of algae and toxic bacteria, and obnoxious accumulations of filamentous algae and vascular plants.

Not only do these activities affect the ecological integrity of inland



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