Sewage Scrutinized for Polluting Indian River Lagoon

Web AdminWater

The summer months often see a rise of blue-green algae problems in Lake Okeechobee and its surrounding estuaries. Along with the algae come various claims of who is to blame. 

Indian River Lagoon
Rachel Brewton holds a rake with green invasive macroalga, Caulerpa prolifera, which has replaced seagrasses in parts of the Indian River Lagoon.
Photo courtesy of Harbor Branch Oceanographic Institute

One thing is certain amid all the debate, nutrient and water-quality issues are an extremely complex problem with no single solution or party to blame. A recent study released by Florida Atlantic University’s (FAU) Harbor Branch Oceanographic Institute sheds more light on factors creating pollution in the Indian River Lagoon. The study suggests that sewage is a key contributor.

The study was published in the journal Marine Pollution Bulletin. The report indicates that current nitrogen fertilizer contributions were 21%, which is much lower than originally suspected. Meanwhile, the report says that sewage from septic systems contributed 79% of the nutrient load. The investigation dug into the impact that fertilizer application blackout periods during the rainy season had in reducing nutrients and curbing algae blooms.

“The deteriorating conditions in the Indian River Lagoon demonstrate the urgent need for more comprehensive mitigation actions as fertilizer ordinances are not likely to be a standalone solution,” said Rachel Brewton, corresponding author of the study and a research scientist at FAU Harbor Branch. “Our data indicate a primary role of human waste influence in the lagoon, which suggests that current management actions have been insufficient at mitigating environmental pollution.”

The initial overestimation of nitrogen contributions from residential fertilizer applications led to broad public support and the passage of numerous fertilizer ordinances along the Indian River Lagoon. “Now, it would be prudent to prioritize reducing human waste nutrient inputs into the lagoon, prior to mitigating the impacts of internal nutrient sources, when possible.