Marco Canal Water Quality Fun Facts

Nitrogen in the Marco Wastewater Treatment Plant (WWTP) sewage reuse water increased by 120% between 2009 and 2019which drove Marco canals into nitrogen impairment. Nitrogen in the sewage reuse water was dropped back to normal levels in 2019 and the canals came out of nitrogen impairment. The sewage plant caused that impairment. 

Marco Island canals have now been out of nitrogen impairment for four years – there is no need to spend $ millions to “fix” the nitrogen pollution sources. The “4e” report submitted to FDEP by the city to justify spending millions on “fixing” the nitrogen impairment in the canals was deceitful – there was no nitrogen impairment in the canals when that report was submitted. The San Marco culvert projects are a gross waste of public funds. 

Canal oxygen in the summertime has dropped 70% in the last four years. Excess phosphorus in the sewage reuse water feeds algae in the canals which results in depleted oxygen. Marco canals are now officially listed as impaired by FDEP for negative oxygen trend. 

Chlorophyll-a (CHLA) is increasing to the FDEP impaired limit – CHLA is a “response” variable for algal blooms – a measure of algal biomass. There is a lot of algae in the Marco canals. 

There are NO LIMITS to the pollutants, nitrogen and phosphorus, that the sewage plant is allowed to dump into the Marco canals in the reuse water. WWTP has an agricultural permit from the FDEP and claims to be “in compliance.” Of course, the WWTP is complying. There are no FDEP reuse nutrient limits to violate. 

Phosphorus is banned in fertilizer on Marco, yet Clean Marco Waters LLC (CMW) reports that the equivalent of 30,000 # of pure phosphorus and 50,000 # of pure nitrogen is put into the canal eco-system with reuse water for irrigation each year. Like one bag of fertilizer in your canal EVERY DAY. The WWTP is violating the fertilizer ordinance. Reuse water nutrients are fertilizer. 

Phosphorus in the Marco canals is now increasing to the FDEP impaired limit – phosphorus is a “causal” variable for algal blooms – phosphorus feeds algal blooms - there is only one source of phosphorus on Marco – the sewage plant. Again, it is the sewage plant. This is the second time. 

Marco canals are exhibiting symptoms of ecosystem decline and collapse caused by excess nutrients in the reuse water. This collapse is the result of a Septic Tank Replacement Program (STRP) coupled with inadequate treatment of reuse water – an unintended consequence. WWTP is violating the FDEP permit which says, “do no harm.” 

Dr. Harper said (twice): “Take care of the reuse water first.” 

The WWTP claims that reuse nutrients cause no environmental harm. This is false. Reuse nutrients leach through the sandy soil and flow directly into the canals, feeding algal blooms. 

C-HAWQ proposes a “downstream” project to dredge the canals for a staggering $60,000,000 and fill in the bays of Marco Island. Promoters claim the Harper Report (2021) as justification for dredging. Dr. Harper said (twice) “I do not recommend dredging on Marco Island.”  

A response to the city issued Request for Information (RFI) for technologies to reduce nutrients in reuse water, a firm called NuQuatics estimated the cost for an “upstream” project to remove 99% of the nutrients from the reuse water at the pollution source, the WWTP, was just $5,000,000.Upstream costs much less than downstream.