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Water Quality Fact Sheets
Phosphorus
Parameter: Phosphorus Abbreviation: P
Classification: Nutrient Surface or Ground Water? Surface Water
EPA Priority Pollutant? Yes Is it Carcinogenic?
No
How is it Measured? milligrams per liter or mg/L
Illinois EPA General Use Standard: Lakes are allowed
maximum Total Phosphorus concentrations of 0.05 mg P/L. No Standard for
rivers and streams, but lEPA considers 0.61 mg Total P/L to impair aquatic
life.
What you should know about Phosphorus:
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Phosphorus is an important component of organic matter. As a
constituent of nucleic acids in all cells, it is vital for all organisms.
In streams and rivers, P is usually the limiting nutrient that prohibits
additional biological productivity (algae). |
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Phosphorus enters streams and rivers not only through stormwater
runoff, but also naturally through mineralization of phosphates in the
adjoining soil and rocks, or from man-made sources. |
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Phosphorus is measured in two ways, total phosphorus and dissolved
phosphorus. Since phosphorus can be bound to sediment (like clay),
phosphorus often measured by figuring how much phosphorus has become
attached to the suspended solids. Dissolved phosphorus measurements
provides insight as to how much of the phosphorus entering a stream is
from point sources (Streams with high total phosphorus and low dissolved
phosphorus levels usually have most phosphorus input from non-point source
pollution, like agriculture, and urban areas.
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Major Sources of Phosphorus:
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Urban Runoff contributes 0.2-1.7 mg/L of phosphorus during rainfall
events. Livestock operations, like feed lots, can contribute up to 4-5
mg/L. Untreated Wastewater usually contains around 10 mg/L, and effluent
from wastewater treatment plants with secondary treatment release about 5
mg/L. |
Minor Sources of Phosphorus:
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Malfunctioning Septic Systems, Illegal dumping, residential
fertilizers |
Typical Concentration for the Fox River Watershed:
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Less than in 0.15 mg/L of dissolved phosphorus in the upper watershed.
More than 0.3 mg/L dissolved P in the lower Fox Watershed. Agricultural
and more urbanized streams may have much higher concentrations, over 0.45
mg/L. |
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Average Total Phosphorus loads in the Fox River are in excess of 2,500
kg/day (that’s 5,500 pounds of phosphorus discharged into the Illinois
River every day!). |
Impacts to Ecosystem:
- Promotes algae blooms, which inhibits aquatic plant growth and reduces
dissolved oxygen levels. This ultimately decreases or wipes out the sport
fishery, leaving only "rough" fish like carp.
Impacts to Drinking Water: Not Applicable
Impacts to Recreation:
- High phosphorus in lakes and in the impoundments of dammed rivers
promotes eutrophication. This causes high algae levels, low dissolved
oxygen, and smelly odors. This degrades game fish populations and
discourages recreational boaters.
References
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IEPA, Illinois Water Quality Report 2000, April 2000.
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IEPA, Baseline Loadings of Nitrogen, Phosphorus, and Sediments from
Illinois Watersheds, Nov. 1999. |
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Maidment, David R., Handbook of Hydrology, 1997.
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