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Phosphorus Pollution
It's causes, effects, and measures for protection
PRIMARY "NUISANCE" NUTRIENT : PHOSPHORUS
What is Phosphorus?
Phosphorus is a necessary and natural element found in rocks, soil and our bodies! An essential nutrient for animals and plants, it is a common ingredient in fertilizers, and human sewage is a rich source of phosphorus. Of all elements, phosphorus is the key to managing lakes as "clean" or "green".
How Does Phosphorus Get Into Lakes?
Phosphorus clings to soil and is carried or “exported” from forests and fields into lakes and streams by water from rainstorms and snow melt. Export can also occur when land is developed or paved. The natural filters and sponges of vegetated soil are reduced or eliminated, greatly increasing phosphorus export to lakes (see NH LAKES brochures Shoreland Protection and Shoreland Plantings).
Paved surfaces also allow water from storms and other sources to move very quickly and wash into streams and lakes along with other phosphorus-containing pollutants such as motor oils and fuels.
What's the Problem with Phosphorus?
Phosphorus is an element essential to plant life and is present in most fertilizers. But what makes your lawn and garden green can also make your lake green by promoting an overgrowth of algae and weeds. Each season, algae and weeds die, fall to the lakes bottom and decay. The decay process deprives water of oxygen and causes fish and other aquatic life to die. Their decay further feeds the cycle that increases algae and weed growth (see NH LAKES brochure A Brief History of Lakes). Water becomes cloudy, gets an unpleasant odor and taste, losing its appeal for swimmers and boaters which often causes property values to fall. Increased phosphorus, even in small amounts, reduces water quality.
Where Does Phosphorus Come From?
Sources of phosphorus include:
- Eroded soil
- Leaves and grass clippings
- Paint and paint thinner
- Garbage
- Soaps and detergents
- Household chemicals
- Gasoline, motor oil, and other greases
- Road dust
- Lawn fertilizer
- Pesticides
- Animal waste including pet droppings
- Improperly maintained septic systems
Phosphorus can come from all over a watershed (see NH LAKES brochure What is a Watershed?). A lakes watershed consists of all of the surrounding land where water drains into that lake. Water quality protection must occur throughout the watershed. Poorly designed developments – even those that are far from a lake or stream can have devastating effects on water quality.
Controlling phosphorus
Keeping phosphorus out of New Hampshire's lakes is the most important thing that you can do to
protect water quality. Phosphorus pollution can be reduced by:
- Limiting the size and density of construction projects
- Minimizing impervious surfaces such as paved surfaces and roof areas
- Keeping soils covered with vegetation
- Eliminating use of pesticides and other yard and garden chemicals
- Fertilizing properly and in appropriate areas
Excess fertilizer can runoff and pollute nearby water. Testing lawns and gardens prior to fertilization
enables you to apply only what your soil needs. Using only lime and slow-release nitrogen fertilizers
in shore areas further protects water quality (see NH LAKES brochure Shoreland Protection for further information about the Comprehensive Shoreland Protection Act).
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