Class

Examples

Major Sources

Nutrients

Nitrogen,

phosphorus

Wastewater treatment plants, fertilizers, leaking septic tank systems, animal wastes, agricultural return flows, sediment

Production of excess algae. When algae die, decomposer organisms consume them. This process can use up most of the oxygen in the water, harming cold-water fish species and other aquatic organisms.

Sediments

Soil, sand, silt, dust, gravel

Erosion of soil by water or wind, road de-icing, storm drains

Harms habitat and reproduction of fish and other aquatic life.

Pathogens

Bacteria, viruses, parasites

Agricultural return flows, cattle, horses, humans, leaking septic systems, storm drains

Makes water unsafe for human consumption and recreation.

Toxins

Hydrocarbons, heavy metals

Chemical spills, automobile products and emissions, street runoff, improper use of storm drains, leaking underground petroleum storage tanks, mining activities, industry, improper use of pesticides, etc.

Harms wildlife, fish and human drinking water.

Salinity

Total dissolved solids (TDS),

salts

Agricultural return flows, wastewater treatment plants, geothermal springs

Accumulates in agricultural fields, terminal lakes and wetlands in the Great Basin.

Thermal Pollution

Increased water temperature

Agricultural return flows, geothermal springs, loss of streamside tree canopy

Water holds less dissolved oxygen; harms fish and other aquatic life.