Green Lawns, Lagoon Doom

March 31, 2016

Article published in Coastal Angler Magazine in 2004


Green Lawns, Lagoon Doom


By Captain Tom Van Horn


Last summer while fishing in the area of Port St. John’s power plants, I witnessed an unusually high number dead fish floating in the lagoon.  Living in Florida all of my life, I’ve seen fish kills before, but this was the first I had ever seen in the Indian River Lagoon system.  This incident disturbed me, and it provoked my curiosity.   Fish kills are becoming a common summer time occurrence in many inland lakes and near-shore waters of Florida, and I was determined to learn more about their cause and steps I could take to lessen my impact.


I began my investigation by discussing the incident with Doctor Grant Gilmore, a renowned marine biologist/sociologist, who has studied the Indian River Lagoon for over 30 years. What he told me disturbed me even more.  He stated the Indian River Lagoon system was set up for an ecological disaster due to its lack of circulation, and high concentration of nutrients in the water and the heated effluent discharged from the power plants. I also learned the primary reason for the fish kill was the lack of dissolved oxygen in the water caused by a decaying alga concentration.


Alga blooms are naturally occurring in Florida waters, but their impact is greatly influenced by water temperature and the ever-increasing levels of dissolved nutrients.  When the heavy summer rains occur, they flush high concentrations of pollutants, sewage effluent, and nitrogen and phosphorus runoff into the lagoon.  The alga consumes the nutrients added to the water, and it’s rapid growth spread across the water like a carpet shutting off the sunlight from sea grasses. When these organisms die and decay, they absorb the oxygen latterly suffocating marine life.  In many cases, heavy rains flushing urban runoff into the water followed by several days of overcast skies which block sunlight causing the algae to die triggering the fish kills. This decay oxidizes depleting the water of dissolved oxygen.


Although the best measure is to outlaw green lawns, it’s unrealistic for us to think growth and development will slow down anytime soon, and that Floridians will give up their beautiful St. Augustine lawns. Here are some common sense measures we can take to reduce the impact of our lawns on the lagoon and other waters:


Fertilize your lawn only as needed with light application of a dry time-released product (16-4-8) on rain free days.  Many of us do not follow manufactures recommendations, and we apply too much product.  This over application is unnecessary, and it adds to the runoff problem.


If you live on the water, do not spread fertilizer within the last ten feet of the waters edge, and by all means, keep product out of the waterway.  Normal precipitation and irrigation will carry nutrients to the lawn’s edge.


Always remove excess fertilizer and grass clippings from the hard surfaces.  This is best accomplished by sweeping or blowing over spread back onto the lawn. All product left on the street will most likely end up in the waterway.  Also, residual fertilizer will stain hard surfaces and is a waste of money.  If professional services maintain your lawn, request that they remove residual applications. If they refuse, take the time to remove them yourself or hire a service that is more environmentally friendly.


When mowing, mulch your grass clippings back into the lawn.  Bagging clippings removes nitrogen from the lawn and is costly to remove to landfills. The more nitrogen you remove, the more fertilizer you need. 


When mowing, never discharge clipping into the street or the water.  Decaying clippings have the same effect as decaying alga in the water, and clippings left in the street will eventually end up in the waterway.


Lightly apply pesticide and herbicides only as needed directly to areas of infestation and always follow manufactures recommendations.   Never discharge lawn chemicals into the waterway.


When developing waterfront property, leave a natural buffer along the waters edge, or create a reverse swale to keep lawn runoff out of the lagoon.


Incorporate a rain shutoff switch into your automatic irrigation system.  This inexpensive modification will save water and reduce runoff by turning off your system during periods of rain.  Consistent watering of approximately one inch every three days is all that’s needed to support a healthy St Augustine lawn.  Excess watering is a waste of resources.


Adjust and maintain you irrigation system to keep water where it is needed, on the lawn.


Serve as an example to your community by being a good Stewart of the Lagoon and the environment.


Transform you lawn and landscape into a natural xeric plant community and eliminate grass as much as possible.


These simple tips will save you money, improve the quality of your lawn, and help reduce the level of nutrients discharged into the watershed.  Remember, these principles do not only apply to waterfront residents, but to all of us who chose to live in Florida. 

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