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Phosphorus affects Illustration
What is phosphorus?

Phosphorus is a naturally occurring nutrient and under natural conditions enters the water through the weathering of rocks and precipitation of dust. Phosphorus is a limiting nutrient in the freshwater systems of the Puget Sound lowlands area. It is similar to nitrogen in marine environments in that when there is too much or too little it can change how an ecosystem functions. Phosphorus is never truly lost or destroyed; it moves from one system to another.

When is phosphorus problematic?

Increases in phosphorus can lead to problematic changes in freshwater such as increased algae and a subsequent loss of deep water oxygen.

What affects phosphorus levels?

Wetlands slow down water flow and the plants nearby can absorb some of the phosphorus moving through. When wetlands are lost, this ability to remove the phosphorus from the system is eliminated. Phosphorus can also be adsorbed by soils, infiltrate the ground and be adsorbed by soil before entering surface water.

Phosphorus is often increased in streams and lakes by livestock manure, fertilizer from lawns and gardens, pet and goose waste, wastewater flow from faulty septic systems and impervious surface.

Detention ponds, sand filters, and other surface water facilities can intercept or impede phosphorus, but are generally not a complete substitute for natural systems.

References: Stanley 2005 (Acrobat pdf file)