Chemical - Commercial fertilizers and pesticides are two of the major technological breakthroughs of the 20th century. They have given us a means to make soils more productive and to combat pests that threaten our crops. When misused, however, many agrochemicals pose a hazard. Improper management of pesticides and fertilizers can result in contamination of both the surface and groundwater in Idaho

Irrigation - Improved irrigation efficiency can alleviate water quality problems. Reduced conveyance seepage losses will result in less salt pickup during subsurface transport. Reduced tailwater runoff (return flows) from irrigated fields will result in less soil erosion and fewer adsorbed phosphate fertilizer being transported to downstream water bodies. Reduced deep percolation losses below the crop roots will also result in less transport of nitrate fertilizer to the ground water and less salt pickup.

There are many causes for water quality impairments, but one source is runoff or other discharges from animal feeding operations. These operations, where large numbers of animals are grown for meat, milk or egg production can increase the biological waste loads introduced into the waters of the Bear River. Animal manure contains nutrients, pathogens and salts.

Nearly 40 percent of the U.S. phosphate reserves occur in the in the Bear River drainage. The mining exposes the phosphate and other chemicals to the air and water. When too much phosphate is present, algae and water weeds grow wildly and choke the waterway, using up the large amounts of oxygen and causing many aquatic organisms to die.

The primary sources of pollution from forest activities are:

• logging roads
• stream crossings
• skid trails and log loading
• near-stream logging . Link to logging forestry for small operators b. Roads (expand)

Densely populated urban areas, which are covered by non-permeable surfaces like streets, sidewalks and buildings, create a great deal of runoff. The high concentrations of people in these areas tend to produce greater quantities and varieties of pollutants, including nutrients, bacteria, and toxic chemicals. Automobiles and manufacturing are two primary sources of pollution.