Focus on Phosphates


One pound of phosphorus can grow 700 pounds of algae.

Phosphorus is a naturally occurring element and a crucial nutrient for plant growth. In abundance, however, phosphorus can cause many problems in our waterways. In Washington, at least 260 water bodies are polluted because of nutrients like phosphorus. Increased phosphates accelerate plant and algae growth.

Bacteria that feed on dead plants and algae consume more oxygen in the water, leading to less available oxygen for aquatic life. Some of the most common causes of phosphorus pollution are nonpoint household sources like fertilizers, leaking septic tanks and pet waste.

The State of Washington has already taken many steps to reduce the amount of phosphates being washed down our pipes. Since 1994, phosphates levels of over 0.5% have been banned in laundry detergent; since 2010, dishwashing detergents with over 0.5% phosphorus have also been banned. Phosphate-free laundry and dishwashing detergents are widely available in local stores.

Effective January 1, 2013, lawn fertilizer for sale in Washington must not contain any phosphorus unless the use of a soil test shows a Phosphorous deficiency. Since South Sound soils tend to contain naturally-occurring phosphorus. (Existing supplies are allowed to be used up.)

On front of the bags of fertilizer, there are usually three numbers listed prominently on the bag. These numbers correspond to the amounts of nitrogen, phosphorus and potassium (N,P,K). Look for bags with 0 as the middle number to avoid phosphorus.

While laws go a long way to decrease phosphates released into our waterways, there are still many things that you can do:

  • Read labels and buy phosphate-free laundry and dish detergents
  • Get your lawn’s soil tested to determine any fertilizer needs
  • Use slow-release, phosphate-free fertilizer on your lawn, if needed
  • Keep fertilizer off of hard surfaces and sweep any up that gets on sidewalks.
  • Put food scraps in a compost or worm bin, not down the garbage disposal
  • Maintain your septic system and regularly check for leaks
  • Pick up your pet’s waste; every dog, every doo, every time