Interpreting L-THIA's Results: Common Sources of NPS Pollution

Excess fertilizers, herbicides, and insecticides from agricultural and residential areas.

• Oil, grease, and toxic chemicals from urban runoff and energy production.
• Sediment from improperly managed construction sites, cropland and eroding streambanks.
• Salt from irrigation practices and acid drainage from abandoned mines.
• Bacteria and nutrients from livestock, pet wastes, and faulty septic systems.
• Atmospheric deposition and hydromodification are also sources of nonpoint source pollution.