In Depth

Toxic Algae: How Poor Wastewater Management And Bad Agricultural Practices Slimed Florida

By: Gary N Roderick, CEP, REM, CEA and Greg Leatherman, Editor in Chief of ECO Magazine

ECO Magazine is headquartered in the seaside community of Stuart in Martin County, Florida. Perhaps you’ve seen Stuart in the news recently. Images of its algae-tainted water have been shared around the globe on national and international media outlets. There’s plenty of blame to go around for this disaster, and there are both challenges and potential solutions for solving it, but one thing for certain is that toxic algae makes people sick—and not just metaphorically.

Two weeks ago, ECO’s Greg Leatherman visited a matted blue-green algae bloom at Central Marine across the St. Lucie River from Stuart. According to a report issued 26 July 2016 by Martin County, Florida, the algal bloom at Central Marine contains microcystin at a rate of 33,000 parts per billion. The World Health Organization considers anything over 10 parts per billion hazardous, and microcystin can cause nausea, vomiting, rash, fever, and even liver damage.

Unfortunately, microcystin is not just in Martin County’s water; it has tainted the air. Greg walked around the marina wearing an air filter over his mouth and nose, but that wasn’t enough protection. In just 20 minutes, he breathed in enough of the poison to make his throat scratchy and caused a headache. He wasn’t alone. Others who visited the site that day reported the same symptoms—tests downwind of this same site found microcystin in the air at a rate of 0.64 parts per billion. Tests also found large amounts of hydrogen sulfide in the air. Furthermore, Dr. Larry Brand of the University of Miami recently informed clean water advocates (The Rivers Coalition) that a toxin called BMAA contained in these blooms “can lead to neurodegenerative disorders like Alzheimer’s and Parkinson’s and ALS.”

Dr. Brand added that while the evidence is not all in, “There’s good reason to believe that there are a bunch of other toxins in these blooms of cyanobacteria which have not been discovered which can also have long term health effects.”

Speaking to the Stuart News, Deborah Drum, Martin County’s ecosystem restoration manager, said “People need to stay away from areas where blue-green algae has accumulated.”

A lot of folks in Martin County live along canals, the river, the lagoon, or the ocean. All of them, even beaches, are suffering from toxic algae during the summer of 2016. In many places, the creatures that depend on these waters are struggling to survive.

There are concerns that prolonged blooms will shade and kill seagrass, eliminating the manatees’ primary food source. Photo credit: Rebecca Fatzinger.

There are concerns that prolonged blooms will shade and kill seagrass, eliminating the manatees’ primary food source. Photo credit: Rebecca Fatzinger.


For example, according to Dr. Katie Tripp, Director of Science and Conservation at Save the Manatee Club, “…In the north Indian River Lagoon (IRL), small numbers of manatees have once again started to die from an ongoing Unusual Mortality Event that has killed more than 150 and is believed to be tied to a loss of seagrass linked to algal blooms that started more than 4 years ago. In the southern IRL, manatees are swimming through putrid waters impacted by discharges from Lake Okeechobee. As in the north IRL, there are concerns that these prolonged blooms will shade and kill seagrass, eliminating the manatees’ primary food source (and an important habitat for other marine species).”

It’s not just people, animals, and plants. The economy is also unwell. Tourists don’t just come to Martin County for beaches. They sail. They waterboard. They fish. The area is renowned for its ocean fishing and the freshwater fishing here is legendary. One of the best tasting game fish—snook—is not legal to buy or sell, but it is delicious when fresh caught and grilled over an open fire. Of course, it’s not nearly as appetizing when suffering from open ulcers or microcystin poisoning.

As a result, bait and tackle shops are closing their doors, fishermen are pulling up crab traps, waterfront properties are losing value, and tourist-based businesses like Treasure Coast Sailing Adventures question whether they can survive the downturn. When Captain Fred Newhart docked his double-masted schooner during the days he would normally book cruises, he told ECO, “I can’t ask a first mate to work in unsafe conditions or take people on a toxic sunset cruise.”


The Biosolids Sleight-of-Hand
On the surface, the cause of the algal bloom is simple: too many algae-supporting nutrients in the water. We know this not only by observing the bloom, but via realtime observations by the Ocean Research & Conservation Association (ORCA) using Kilroy monitors placed in the Indian River Lagoon.

One algal bloom contained microcystin at a rate of 33,000 parts per billion. The World Health Organization considers anything over 10 parts per billion hazardous. Photo credit: Rebecca Fatzinger.

One algal bloom contained microcystin at a rate of 33,000 parts per billion. The World Health Organization considers anything over 10 parts per billion hazardous. Photo credit: Rebecca Fatzinger.


According to a 2016 report from the U.S. Environmental Protection Agency (EPA),53% of Florida’s rivers, 82% of its lakes and reservoirs, and 32% of bays and estuaries are impaired by nutrients, specifically total phosphorus (TP) and total nitrogen (TN). These surface waters include the most environmentally diverse estuary in North America (Indian River Lagoon), the second largest freshwater lake contained entirely within the contiguous 48 states (Lake Okeechobee), and the Everglades (a UNESCO and Ramsar Convention designated Wetland of Global Importance).

The designation of these Florida surface waters as impaired results from a mandate from the federal Clean Water Act, which also requires the State to implement programs to reduce nutrient pollutant loads through the establishment of Total Maximum Daily Loads (TMDLs) designated for most of Florida’s waters. However, the State of Florida continues to enable polluting by allowing a “sleight of hand” by the State Legislature, the Florida Department of Agriculture and Consumer Services (FDACS), the Florida Department of Environmental Protection (FDEP), the utility industry, and the agricultural industry of Florida.

Nutrient impairment of waterways is normally defined by the amount of TP and TN finding their way to surface waters from upland sources. If the import of TP and TN in a contributing watersheds exceed the export then there will be a surplus of nutrients available to be discharged to Surface waters by rainfall runoff. Biosolids, which contain both nitrogen and phosphorus, are often used as fertilizers in Florida. These biosolids are end products of wastewater treatment plants, and their use is labeled as “beneficial” use of wastewater by the FDEP. However, most Florida soils do not require any additional phosphorus to supplement agricultural production. The majority of agricultural production in Florida includes citrus, cattle (pasture/sod), sugarcane, and vegetable row crops. Nitrogen is only required in small supplemental amounts for these crops. Yet the State allows over 13.2 million pounds of TP and 33 million pounds of TN to be applied within Florida watersheds annually

Generally, wastewater treatment plants convert the effluent from urban and residential central sewer systems into three forms of biosolids, which are termed Class AA, A, and B. According to a March 2016 article appearing in the online publication Treatment Plant Operator, operators at a water reclamation facility in Ocala received the Florida Water Environment Association Biosolids Management Award for Small Operations in 2013. Their facility produces a Class AA biosolid distributed and marketed as Nutrisource. Ocala boasts crystal clear streams and rivers, and when asked why his plant does not landfill the biosolids his plant produces, Robin Preston, lead operator, stated, “Land-filling of biosolids or land spreading would not be acceptable here. We need to keep nitrates out of the groundwater.” Class AA biosolids have been processed and, in many cases, mulched with landscaped material into common “pelletized” or dried forms.

The creatures that depend on these waters are struggling to survive. Photo credit: Rebecca Fatzinger.

The creatures that depend on these waters are struggling to survive. Photo credit: Rebecca Fatzinger.


Class A and B biosolids are generally still in a “liquid” form and are sprayed on agricultural lands. Once land applied, nutrients from the biosolids can be easily washed into “surface waters” via overland drainage from rainfall into agricultural swales, ditches, and canals, which eventually lead to lakes, rivers, streams, estuaries, bays, and other coastal systems.

Florida Administrative Code (F.A.C.) 62-640.700 states that biosolids can only be applied by permit and must have a valid Nutrient Management Plan (NMP). After reading the legislation, one might conclude that biosolids in Florida are being regulated and applied in a very careful manner. However, the Florida legislature also passed F.A.C. 62-640.850, which indicates that if Class AA biosolids are “Distributed and Marketed as Fertilizer,” then they are not subject to the requirements of the previous referenced F.A.C. 62-640.700. This is the very definition of a regulatory loophole.

Class AA biosolids termed “fertilizer” may be land applied totally unregulated. These biosolids termed “fertilizer” are produced by the wastewater utility industry, which is more than willing to give away “fertilizer” at extremely cheap rates or even pay to have the “fertilizer” removed for land application just to dispose of the byproduct from wastewater treatment. The agricultural industry is eager to accept this cheap form of “fertilizer.”

River of Tears by MARMO. A native Floridian, he finished this oil on canvas painting in July 2016 as a lasting reminder that damage done to the St. Lucie River and estuary is not limited to a singel summer or a 24-hour news cycle. To see more, visit

River of Tears by MARMO. A native Floridian, he finished this oil on canvas painting in July 2016 as a lasting reminder that damage done to the St. Lucie River and estuary is not limited to a singel summer or a 24-hour news cycle. To see more, visit


The three major sources for the import of nutrients into Florida watersheds are food, manufactured fertilizer, and biosolids. Of these three major sources, food will continue to be imported unchanged and even increase with population growth. Food is consumed and the end products are deposited in septic systems and wastewater treatment facilities. Manufactured fertilizer will continue to be imported, but it is self-limiting as land owners will not over-fertilize with this material because of the higher cost associated with its production. Manufactured fertilizer has the added benefit that it can be blended without phosphorus, as Florida soils generally do not need phosphorus to supplement crop production.

This leaves reduced application of biosolids fertilizers as the most likely option for effectively reducing excessive amounts of nutrients in the watershed. It’s simple logic. If we weren't over fertilizing agricultural lands, agricultural soils would exhibit a reduction of nutrients and the concentration of nutrients in surface waters would go down. Instead, the concentration of nutrients in surface waters has been increasing and is currently high and impairing surface waters.

The only way the concentration of nutrients can be high in surface waters in rural areas is if we are over fertilizing agricultural crop land. However, all of the recent legislation to reduce nutrient loading to surface waters exempts Class AA biosolids from being regulated.

Furthermore, if the regulation of Class B biosolids were to become too burdensome, the industry would simply enhance the processing of Class B biosolids into Class AA biosolids, so that the material could be land applied within the watersheds totally unregulated. Part of the exemption is included in F.A.C. 62-640.400 “Prohibitions”. The exemption extends to other portions of the Florida Statutes, such as F.S. 373.4595, as part of the Northern Everglades and Estuaries Protection Program and the Lake Okeechobee Protection Program. None of these exemptions mention nutrient load reductions to meet the federally mandated TMDLs.

According to a 2014 FDEP Biosolids Report, Florida produces approximately 300,000 dry tons of Class AA and B biosolids each year (little or no Class A biosolids are currently produced in Florida). Approximately 100,000 tons of Class B biosolids are deposited in landfills, and 100,000 tons of Class B biosolids are land applied on agricultural properties. The remaining 100,000 tons of Class AA residuals are processed with material from the landscape industry, composted, pelletized, or alkaline treated to produce approximately 200,000 dry tons of Class AA “fertilizer.”

To put this in perspective, a 2009 Audubon Report indicates that Class AA and B biosolids “contain an average that varies around about 5.5 percent nitrogen and 2.2 percent phosphorus.” Therefore, each year, 300,000 dry tons of Class AA and B biosolids would contribute 33 million pounds of nitrogen and 13.2 million pounds of phosphorus into Florida watersheds from wastewater-treated biosolids. But according to the NMP for Class B biosolids, you could put over 10,600 dry tons of Class B biosolids on 1,100, 2,400, or 4,500 acres of land.

Meanwhile, the FDEP 2013 Summary report says: “While any class of biosolids may be land-applied, biosolids land-applied in Florida appear to be exclusively Class B.” This statement is made with the FDEP and FDACS knowing full well that Class AA biosolids are being land applied unregulated under the designation of “marketed and distributed as fertilizer.”

The 2009 report by Florida Audubon estimated that biosolids are being applied at 450 to 1,620 times the ideal level to meet the TMDL established for Lake Okeechobee. At that time, the State was to pass legislation to limit TP and TN in certain water-sheds, including Lake Okeechobee. A follow-up publication by Florida Audubon (2013) stated concern about the lack of documentation of “Class AA bio-solids” (human sewage sludge) still allowed to be used as fertilizer in the Northern Everglades basin. The 2013 Audubon document states that FDACS personnel indicate they have no way of measuring just how much of this nitrogen- and phosphorus- laden material is spread on farms in the watershed. However, the recently released 2016 South Florida Environmental Report, Appendix 4.1 states, that “The five-year (WY2011–WY2015) average TP load to Lake Okeechobee is 436 mt per year, which exceeds the TMDL by 296 mt.”[12]

A map depicting where AA residuals are marketed and distributed as fertilizer used to be included in the FDEP yearly summary for biosolids. However, this map has not been included in the summary report since 2011. In the last year for which the map was provided (2009), the quantities of biosolids marketed and distributed as fertilizer in many watersheds discharging to Lake Okeechobee and the Indian River Lagoon exceeded 10,000 dry tons per county!

As a result, the primary agricultural canals conveying water from large agricultural watersheds characteristically convey surface waters that have nutrient concentrations 2, 3, or even over 5 times the targets adopted by the State for lakes, streams and estuaries. Since the majority of biosolids in the State of Florida are land applied within water-sheds that drain into the Indian River Lagoon, Lake Okeechobee, and the Everglades,the results are predictable: massive toxic algae blooms.

In 2007 through 2008, the South Florida Water Management District contracted to produce three tasks in a document entitled “Technical Assistance in Review and Analysis of Existing Data for Evaluation of Legacy Phosphorus in the Lake Okeechobee Watershed.” The report details, in Task I, that the contribution of nutrients as phosphorus is relatively low for residential fertilizer, biosolids (specifically Class B) and septic fields. The majority of nutrients are finding their way to surface waters from agricultural fertilizers, which are predominately Class AA biosolids being “marketed and distributed as fertilizer.” Although this report is specific for phosphorus, the same conclusions would be reached for nitrogen as both phosphorus and nitrogen are supplied in high concentrations from class AA biosolids.

These trends have also been reported by Harvey H. Harper (Ph.D., P.E.), who showed in an analysis of Florida nitrogen fertilizer consumption from July 2010 to June 2011 that farm consumption was 130,969 tons, while all other applications combined (lawns, athletic, gardens, rotten plants, and nursery) combined were less than 31,000 tons. The numbers for phosphorus were even more disparate, showing a ratio of farm consumption to all other uses of 8 to 1.

There have also been studies done to try to chemically distinguish urban sources of such nutrients from agricultural sources. However, since the majority of fertilizers are class AA biosolids, there is no study yet that can chemically distinguish the phosphorus or nitrogen radicals that originate from urban septic systems versus Class AA biosolids or Class B biosolids. In other words, you cannot accurately determine whether the N or P component in surface waters originate from agricultural lands fertilized with Class AA biosolids or from failed urban septic systems. That includes recent studies using markers such as caffeine and sugar substitutes, which is why current estimates of contributions are usually based on land use and groundwater flow.

What we do know is that if the import and export of phosphorus today were equal in the Lake Okeechobee basins, it would take 350 years of rainfall runoff to wash the existing legacy phosphorus out of the soil to meet the current established TMDL for Lake Okeechobee.


What About Solutions?
The October 2014 issue of ECO included an article by M. Perry outlining the science behind sending more water from Lake Okeechobee south towards the Everglades. According to the Florida Audubon Society, the South Florida Water Management District owns approximately 16,000 acres of land in the Everglades Agricultural Area that will be used in the Central Everglades Planning Project, which is pending congressional authorization. The land is currently being leased to a private company for sugar cane cultivation. The Florida Audubon Society recommends the State utilize this site as a short-term dispersed water management project. Holding 3 ft of water on this land—typical storage in a dispersed water management project—would total more than 13 billion gallons of water. This is equivalent to 10 days of maximum discharges of Lake Okeechobee water to the St. Lucie River.

Limiting or eliminating biosolids is the only effective way to reduce nutrient enrichment within Florida’s impaired waters. Photo credit: Rebecca Fatzinger.

Limiting or eliminating biosolids is the only effective way to reduce nutrient enrichment within Florida’s impaired waters. Photo credit: Rebecca Fatzinger.


Other money for land acquisition has already been approved and paid for by Florida voters via 2014’s Amendment One. Those monies were pilfered by the Florida Legislature, and a lawsuit filed in Leon County Circuit Court on behalf of multiple non-profits is currently underway to try to halt this raid. A ruling could even come down by the time you receive this issue of ECO, so stay tuned. We will report the results.

But even if we send the water south, the State of Florida still allows the unregulated land application of hundreds of thousands of dry tons of biosolids within the State’s watersheds. Limiting or eliminating this source of nutrients is the only effective way to reduce nutrient enrichment within Florida’s impaired waters.

The answer to this part of the problem is to implement alternative disposal options for biosolids other than land application in Florida. These solutions include exporting the biosolids to areas deficient in nitrogen and phosphorus or converting the organic and nutrient components of the biosolids into usable energy. According to the International Soil Reference and Information Centre, areas in South and Central North America and areas in the Caribbean adjacent to the State of Florida are in need of nitrogen and phosphorus enhancement from soil degradation. In fact, their data show that Central America has the highest percentage and worst degrees of soil degradation. Furthermore, technologies such as converting biosolids to biofuels and plasma gasification (arc plasma) are emerging as an energy alternative for biosolid waste disposal. All options must be on the table for Florida.


This article benefited from the ongoing coverage of the Stuart News.

  1. U.S. Environmental Protection Agency. 2016. Waters Assessed as Impaired due to Nutrient-Related Causes.

  2. Force, Jim. 2016. The Road to Producing Florida’s Class AA Biosolids.

  3. Florida Administrative Code, 62-640, Biosolids.

  4. Florida Statutes (F.S.) Title XXVIII, Natural Resources; Conservation, Reclamation, and Use 373.4595 Northern Everglades and Estuaries Protection Program

  5. Florida Department of Environmental Protection. 2014. Biosolids in Florida – 2013 Summary

  6. Florida Audubon. 2009. Disposal of Sewage Sludge in the Lake Okeechobee Watershed Is Hurting Everglades Restoration.

  7. Audubon of Florida. 2013. Bold Steps Needed for a Healthy Lake Okeechobee.

  8. Yun Qian, Kati White Migliaccio, Yongshan Wan, and Yuncong Li. 2007. Surface water quality evaluation using multivariate methods and a new water quality index in the Indian River Lagoon, Florida, Water Resources Research, Vol. 43, W08405, doi:10.1029/2006WR005716.

  9. Soil and Water Engineering Technology, Inc. in association with JGH Engineering Technical Assistance. 2007-2008. Review and Analysis of Existing Data for Evaluation of Legacy Phosphorus in the Lake Okeechobee Watershed.

  10. Harvey H. Harper. 2014. Environmental Research & Design, Inc., Florida Fertilizer Ordinances - The Good, the Bad, and the Ugly, Presentation to the Florida Stormwater Association 2014 Annual Conference.

  11. Mark Perry. 2014. Lake O Discharges: There is a Silver Bullet, Volume 2, Issue 8, ECO Magazine.

  12. R. Thomas James and Bruce A Sharfstein. 2016. South Florida Water Management District. 2016 South Florida Environmental Report. Appendix 4-1: Annual Permit Report for Lake Okeechobee Water Control Structures Operation.

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