Causes of too much algae: excessive nitrogen

by Caroline Brown

In my last post, I blogged about some of the consequences of too much algae in waterways. Some algae is beneficial, but an excess can cause problems. What causes the natural process of algae production to go into overdrive? Too much nitrogen is usually the culprit.

As usual, too much nitrogen is the result of the ultimate invasive species….human beings.

Sewage discharge. The major source of excess nitrogen comes from sewage treatment plants and failing septic systems and cesspools.

Sewage treatment plants discharge cleaned and treated liquid waste—loaded with nitrogen—into water bodies. In addition, combined sewer overflows (CSO) result in the discharge of raw sewage into water bodies. CSOs occur during heavy rainstorms when storm water fills storm drains and overflows sewer systems.

Old and inefficient septic systems and cesspools cause additional sewage discharge. For example, the city of Warwick, Rhode Island has slowly built out its sewer system over the last 12 years, but many residents have not connected in due to high sewer hook-up costs and sewer assessment fees. And according to one estimate, approximately 50,000 cesspools—all considered substandard—exist in Rhode Island.

Homeowners with failing septic systems or cesspools can help by upgrading to new septic systems as soon as possible.

Fertilizers. Although a beautifully manicured yard might seem harmless, a poorly managed landscape can be a source of pollutants that harm water bodies. That’s because the primary ingredient in lawn fertilizer is nitrogen, which helps grass grow and provides it with its lush green color.

Most commercially-produced fertilizers contain too much nitrogen for grass to use at once. The grass uses only what it needs, and the rest is washed from the yard when it rains. It makes its way to the nearest waterway, and eventually, our bays and oceans.

Many commercial fertilizer programs and products encourage the use of too much fertilizer. After all, they make more money if you use more of their product. And many homeowners don’t read the directions carefully, or don’t understand how to properly apply fertilizes.

“Slow release” fertilizers help solve this problem. These products—many of them organic instead of chemically processed—release nutrients into the soil over a long period of time, instead of all at once. This prevents an excess of nitrogen and provides plants with fertilizer throughout the growing season.

Another way to avoid nitrogen runoff is to apply lawn fertilizer only when your grass needs it. Your yard needs fertilizer the most when it’s growing. Once growth has leveled off, a heavy application of fertilizer gives you the satisfaction of turning your grass green but does little else.

Pet waste. Fido’s waste ends up in the nearest water body, unless it’s picked up by Fido’s owner. Pet feces is washed out of yards, down streets and into storm drains, which empty directly into the nearest rivers or streams that feed local lakes and eventually, bays and oceans.

Controlling nutrient pollution from pet waste is easy. Instead of leaving it on streets, curbs, or yards, properly dispose of pet waste by scooping it, bagging it and putting it in your curbside trash. (I find it so disgusting that people leave their pets’ crap lying around–why would anyone do this? Besides the environmental aspects, it’s gross and frankly, rude. Stepping down from soapbox….)

Protecting our precious water resources from too much algae should be a major priority for everyone, so think about the ways that you can help keep nitrogen out of our vibrant waterways. And help educate your friends and neighbors as well.

Photo courtesy of the University of Kentucky School of Agriculture. Parts of this article were first published in the Kent County Daily Times.


5 Comments to “Causes of too much algae: excessive nitrogen”

  1. why does algae needs fertilizer

  2. Thanks for info!

  3. Fungi love dark and wet areas the most.

  4. how does algae affect us?

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