The Phosphorus Future of Marco Island

In August 2019, the average oxygen levels in the Marco waterways were a healthy 6.8 mg/L. By August 2023 the average oxygen levels had dropped to 2.4 mg/L, for a reduction of 65%. 

The Marco Island eco-system is collapsing. 

Phosphorus pollution is a global problem. Phosphorus losses throughout the agriculture – food – sewage systems lead to major environmental damage, through eutrophication. This is one of the greatest causes of freshwater quality failure, an ecological menace for enclosed seas and estuaries, and contributes to marine dead zones. 

This problem is bigger than global warming according to the Stockholm Resilience Center. “Biogeochemical Flows” of phosphorus and nitrogen are the greatest planetary threat. Much of the phosphorus mobilized by humans ends up in aquatic systems. These systems become oxygen starved as bacteria consume the blooms of algae that grow in response to the high nutrient supply. 

According to a book published in 2008, The Algal Bowl (Schindler), over-fertilization of the world’s freshwaters and estuaries represents “… degradation of water comparable with the degradation of land during the great American Dust Bowl of the 1930s.” 

The US Environmental Protection Agency (EPA) website states that “Nutrient water pollution is one of the most widespread and challenging environmental problems faced by our nation. When too many nutrients, mainly nitrogen and phosphorus, enter our waterbodies they cause excessive algal growth. Excess algae can reduce or deplete dissolved oxygen available to aquatic life and, in many instances, produce toxins that can harm people, animals, and aquatic life.” 

Phosphorus is banned in fertilizer on Marco Island. A major “point-source” of phosphorus is reclaimed sewage water from theMarco Wastewater Treatment Plant (WWTP).This facility has a permit from the Florida Department of Environmental Protection (FDEP), yet the Marco WWTP is not required to remove phosphorus from the reuse or reclaimed sewage water distributed to the golf courses and to the condos along Collier Boulevard. This reuse sewage water is considered “liquid fertilizer.” 

The solution is before us. Collier County Pollution Control has recommended upgrading the county WWTP to Advanced Wastewater Treatment (AWT) which removes most of the offending nutrientsfrom the sewage reuse or reclaimed water streams. The Collier Citizens Council supports this recommendation. 

The Collier Citizens Council is a coalition of civic leaders whose purpose is to represent the interests of county residents by influencing local and state policies.