​​Nutrients are essential elements organisms need to live, grow, and reproduce. They occur naturally in our surrounding environment. However, in large quantities, nutrients can be harmful to plants, animals, and water quality.


  • Is a naturally occurring nutrient found in water, soil, and air
  • Stimulates plant growth
  • Promotes natural levels of plant growth when found in balanced amounts
  • In excessive amounts can cause explosive algae growth

Why should I care?

Large algal blooms can cloud the water and block out sunlight for other plants. When algae die, they sink to the bottom of the lake and begin to decompose. Bacteria feed on this decomposing algae and consume the oxygen in the water, depleting dissolved oxygen for other plant and animal life.

In 1998, Lake Whatcom was listed as a polluted water body because it failed to meet state dissolved oxygen standards due to high amounts of phosphorus entering the lake. These resulting water quality problems triggered a Total Maximum Daily Load (TMDL) study by the Washington Department of Ecology.

How does phosphorus enter our lakes and streams?

Phosphorus is a naturally occurring nutrient, however other phosphorus sources from our homes and neighborhoods may include:

  • Exposed soil from construction and landscaping
  • Phosphorus-containing fertilizers
  • Pesticides
  • Phosphorus-containing soaps, detergents, and chemicals
  • Animal waste
  • Failing septic tanks
  • Car washing
  • Leaves and grass clippings

These phosphorus sources can enter our lakes and streams in runoff from rainfall or outdoor water use. As water runs off hard surfaces, like driveways, roads, and patios, it picks up phosphorus-containing sources and carries them into our streams and storm drains, which empty directly into our waterways.

What can I do to help?

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