Phosphorus is an important nutrient for terrestrial and aquatic plants. Therefore, phosphorus is in fertilizer, which explains why the more phosphorus in the water, the more the plants will be able to grow. In aquatic systems, an increase in plant growth causes the water to become depleted of oxygen from the large amount of decomposing plant material. With less oxygen in the ecosystem, large die-offs of fish will occur.

In water systems, phosphorus causes eutrophication of waterbodies. Eutrophication is a natural process in which the lake ages over many thousands of years and becomes more nutrient rich. Eutrophication can be accelerated by adding more nutrients, like phosphorus, to the ecosystem. There are three phases of lake aging: oligotrophic, mesotrophic and eutrophic.

An oligotrophic lake is a young lake with clear water and little productivity (plant and animal life). Mesotrophic is a middle aged lake and a eutrophic lake contains high amounts of plant and algae forms and very low amounts of oxygen. Eventually, a eutrophic lake will become a swamp.

There are many ways in which phosphorus is added to water. Phosphorus is an element that can be found in rocks and minerals.

During natural deposition, or the weathering and wearing of rocks, phosphorus is released into waterways. Soil erosion is a major contributor of phosphorus. Phosphorus attaches to soil particles; making it easily transported through erosion. Summer rain storms and snow melts cause erosion from bare areas on the land and along stream banks; depositing phosphorus into streams and lakes. Along with this movement, some of the phosphorus seeps into the ground.

Non-point sources of pollution are the greatest contributors of phosphorus to the ecosystem. This form of pollution is difficult to monitor and control because it comes from a wide variety of sources and has many triggers. These non-point sources include rock deposition, runoff from storm events and snow melts, including runoff from impervious surfaces (roads, driveways, rooftops), agricultural runoff, erosion and sedimentation from areas that are lacking vegetation to hold soil in place, atmospheric deposition, and input from animal waste and wildlife (waste and carcasses). Point source pollution is a pollutant that can be pinpointed to one location, typically from a pipe that directly drains into a water source.

Although phosphorus amounts from non-point sources are greater, both forms of pollution should be properly addressed and resolved to ensure that the least amount of phosphorus is entering our waterbodies.

The P-Project is an outreach for Cayuga County residents to help them reduce phosphorus loading to local lakes, streams and rivers. Visit www.co.cayuga.ny.us/wqma/pproject/help.htm to find ways that you can reduce the amount of phosphorus entering your watershed.

Sources: Brian Oram, professional geologist, Wilkes University Environmental Engineering and Earth Sciences, 2008, http://www.water-research.net/phophate.htm

- Howard Perlman, U.S. Geological Survey, 2006, http://ga.water.usgs.gov/edu/urbanpho.html

Jessica Miles is the watershed inspector for Owasco Lake.