What is it?
Phosphorus is a necessary nutrient for plant growth.

Why test for it?
If it is present in excessive amounts, it may cause excessive aquatic plant growth and/or algal blooms to occur. When the plants and/or algae die, their decay will accelerate the depletion of oxygen in the water.

Where does it come from?
Sources of phosphorus may be animal wastes, industrial wastes and/or disturbance of soils that naturally hold phosphorus. Specifically, discharges from wastewater treatment plants, septic tanks and storm sewers; soil erosion from construction sites and farms; and runoff containing excess soil and fertilizers from gardens and fields can contribute to increased phosphorous levels.

How can we prevent it from entering our surface waters?
Proper application of fertilizers on lawns, gardens and fields will lessen the impact on stormwater runoff. Ensuring that animal and human wastes are properly handled will help prevent surface water pollution from phosphorous.