The Problem with Phosphorus

Phosphorus enrichment of waterbodies negatively impacts water quality.  The accumulation and internal recycling of phosphorus in water bodies has significant and lasting impacts on the aquatic ecosystem, drinking water supplies and recreational uses.  In addition, excessive phosphorus levels can result in regulatory implications due to exceeding of total maximum daily load (TMDL) thresholds and state and/or federal water quality standards.

  • Excess nitrogen and phosphorus cause algae to grow faster, harming water quality and decreasing the oxygen and food resources aquatic life needs to survive.
  • Harmful algal blooms (HABs) produce toxins harmful to humans, cattle and pets.  

For more information on the impact and problems associated with excessive phosphorus levels in water, visit the following links:

  • EPA- Nutrient Problems
  • EPA- Impaired Waters and Total Maximum Daily Loads (TMDL)
  • USGS- Eutrophication
  • USGS- phosphorus
  • Wisconsin DNR
 A chart displaying trophic status (e.g. oligotrophic, mesotrophic, eutrophic, etc.) alongside phosphorus levels in parts per billion. 

Watershed Management Isn’t Enough

Proactive watershed assessment and management actions are important best management practices to reduce the level of phosphorus entering water bodies. Even when external sources of phosphorus have been curtailed by watershed management practices, the internal recycling of phosphorus in water bodies can continue to degrade water quality and have lasting impacts on the aquatic ecosystem.  'In-Lake' phosphorus mitigation is a critical component of an integrated approach to restore impaired water bodies.