Phosphorus is a nutrient essential to the growth of organisms, and is commonly the limiting factor in the primary productivity of surface water bodies. Total phosphorus (TP) includes the amount of phosphorus in solution (reactive) and in particle form. The analysis for TP provides a measure of the total concentration of phosphorus present in a water sample. Only a portion of TP is readily available for algae growth; however, TP does give an indication of the total amount of phosphorus contained in the various forms of phosphorus. Measured in milligrams per liter (mg/L).

TP concentrations are affected by biological, chemical and physical activity, as well as the various inputs from human activities. Agricultural drainage, wastewater, and certain industrial discharges are typical sources of phosphorus, and can contribute to the eutrophication of surface water. Excess phosphorus in water speeds up plant growth, causes algal blooms and can result in low dissolved oxygen causing the death of certain fish, invertebrates and other aquatic animals.

Source: MPCA