Nitrogen (N) is a key nutrient necessary to the primary production of the system, but can be devastating in excess, causing algae blooms and lowered dissolved oxygen in the water which chokes out life.
The Clean Water Act requires local municipalities to reduce the discharge of nitrogen. Twenty years of data show that these efforts are paying off, as nitrogen levels in some areas of the lagoon have significantly decreased over the past 20 years.
The table below shows how nitrogen scores were generally higher in the decade from 2005–2015, during which we also had sea grass increases. The nitrogen scores severely declined in 2016, the same year the brown tide caused an extensive fish kill in the Banana River and North IRL. In the southern most portion of the South IRL, all water quality monitoring was discontinued in 2013, thus the missing data thereafter.
Nitrogen enters the lagoon through many sources. Water contaminated with nitrogen from fertilizers, septic tanks, leaking wastewater infrastructure, and animal waste enters the lagoon through stormwater drains, canals and seepage. It is also being released by the black ooze known as “muck” that covers about 11% of the lagoon bottom.
The regulatory targets for nitrogen are linked here.
Click here to see how nitrogen scores were calculated.
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