Phosphorous: Important and Detrimental to the Lake Ecosystem

What is Phosphorous?
Phosphorous, a compound common in the lake ecosystem, can be derived from natural organic sources such as animal manures, composts, fallen tree leaves, grass clippings, rainfall, soil and airborne dust. Phosphorous is essential to plant growth and fertility. However, increased amounts of phosphorous entering surface waters can create excessive algae growth which creates problems such as decreased water quality, fowl odor, habitat loss, and fish kills. The problems caused by excessive phosphorous are not only detrimental to the lake ecosystem, but extend to decreased lakeshore property values!

How do excessive amounts of phosphorous accumulate in lakes?
Humans increase the amount of phosphorous entering a lake in two ways, through point sources and non-point sources. Point sources of water pollution are caused by factories and wastewater treatment plants. Non-point sources, commonly known as runoff pollution or stormwater pollution, occurs when rain and melting snow push phosphorus, as well as other nutrients, from the landscape into the lake. Even if one does not live by a lake runoff pollution directly affects the lake ecosystem. Why? Because the waste enters the lakes watershed, the surrounding land area that drains into a lake. Whether it be via natural drainage system or an artificial drainage system the nutrients from our own back yards will wash into the lake.

What damage does excessive phosphorous cause?
High phosphorous levels create �algal blooms,� a floating, green, slimy cover on the lakes surface. The frequency and severity of algal blooms increase along with the lake�s phosphorous concentration. Algae growth can be severe enough that it blocks the sun from penetrating the surface of the lake. This is especially detrimental to the lake�s ecosystem because fewer aquatic plants will be able to produce oxygen through photosynthesis. And when the algae die, the oxygen they produce will be consumed in the decomposition process which robs fish and other aquatic life of this essential element. The loss of oxygen causes the loss of aquatic life which greatly upsets the entire lake food web. And, of course, excessive phosphorous will also decrease the monetary and aesthetic value of lakeshore property.

Problematic landscapes
Urban watersheds: Runoff pollution is especially prevalent in urban watersheds where there is more impervious area; melting snow and rainwater easily carry nutrients to the lake because hard surfaces such as streets, driveways, and rooftops do not allow for absorption. Runoff is swiftly carried to storm sewers and often enter the lake directly.
Lakeshore Bluegrass lawns without �weeds�: Bluegrass lawns extending to the edge of the waterfront without any native grasses or plants is especially dangerous to the wellbeing of the lake ecosystem. The European Bluegrass has very shallow roots and do not absorb and filter nutrients like native grasses do. Bluegrass lawns do not have a chance to protect the lake by reducing runoff in the absorption of nutrients such as phosphorous before entering the lake. Exposed soils on construction sites and steep slopes are also problematic surfaces in dealing with runoff.

HEY! One pound of phosphorous can produce up to 500 lbs. of algal growth once it washes into a lake!