Decades of Nutrient Pollution in the Indian River Lagoon and Possible Solutions

        Nutrient Pollution: Solutions for the Indian River Lagoon

        Nutrient pollution is a type of water pollution in which excessive amounts of nutrients, mainly nitrogen, and phosphorus, enter waterways. Nutrient pollution is the main cause of eutrophication. Eutrophication refers to the growth of algal blooms caused by excess nutrients in a body of water. These algal blooms block sunlight from reaching plant life at the bottom of the waterway, causing them to die off. Once the excess nutrients are exhausted, the algae die, sink to the bottom, and decompose in a process that depletes the amount of dissolved oxygen in the water. Marine life suffocates due to the lack of dissolved oxygen, in an event commonly referred to as a fish kill. The decayed material leads to more nutrients, feeds more algal blooms, causes less oxygen, and more die off, creating a feedback loop.

Sources of Excess Nitrogen and Phosphorus

        Many factors play a part in nutrient pollution of waterways. Sources of excess nutrients can be either point or non-point. Agricultural, municipal, residential, and fossil fuel sources, as well as legacy sediments, all contribute to the issue (U.S. Environmental Protection Agency, 2019).

        Nitrogen and phosphorus are essential to plant growth and are added to crops, in the form of fertilizers, often to excess. Nutrients are also present in animal manure. When these nutrients are in excess, they can run off into surface waters.

        Aging and poorly operating wastewater treatment facilities can discharge nutrients into waterways.

        Fertilizers applied to lawns, pet waste, some soaps, and yard waste contain nitrogen or phosphorus. These excess nutrients can runoff into storm drains, eventually making their way into local waterways. Leaking and improperly maintained septic tanks also release nutrients.

Fossil Fuels
        Power plants, automobiles, and other industrial sources release nitrogen into the air (U.S. EPA, 2019). This excess nitrogen can return to the ground through rainwater.

        Build-up of decomposed material, known as muck, releases legacy loads of nutrients into a waterway when the bottom is disturbed by weather, marine life, or human recreational activity.

Effects on the Indian River Lagoon

        The Indian River Lagoon (IRL) is an estuary situated on 40% of the east coast of Florida (IRL National Estuary Program, 2020). Home to over 4,300 species, the Indian River Lagoon is one of the most biodiverse estuaries in North America (Harbor Branch, n.d.). According to the IRL National Estuary Program (2020), “Fifty-three species of threatened or endangered animals live within the lagoon’s watershed, with Merritt Island National Wildlife Refuge alone containing more than any other national wildlife refuge in the U.S.” (para. 4). Lake Okeechobee, Florida’s largest lake, is connected to the Indian River Lagoon by the C-44 Canal and the St. Lucie River. During periods of heavy rainfall, nutrient-rich water is released from Lake Okeechobee, making its way into the south Indian River Lagoon and the Atlantic Ocean.

Harmful Algal Blooms
        The St. Lucie River is affected by blue-green algae (cyanobacteria) when water is discharged from Lake Okeechobee, resulting in harmful algal blooms (HABs) in 2013 and 2016. In 2018, a blue-green algal bloom was detected in the Indian River Lagoon after one of the Lake Okeechobee discharges (Treadway, 2018).

        In 2011, a green algal bloom (chlorophyta) killed 50 square miles of seagrass in the Indian River Lagoon (Waymer, 2018). Between the 2011 green algal bloom and a 2012 brown algal bloom (Aureoumbra lagunensis), over 47,000 acres of seagrass was lost (Waymer, 2018). Brown algal blooms, also known as brown tide, resulted in a massive fish kill in 2016 and another smaller fish kill in 2018.

        Red tide (Karenia brevis), a harmful algal bloom usually found in ocean waters, was detected in 2018 at low levels near ocean inlets in the Indian River Lagoon (Hodges, 2018).

Effects on Human Quality of Life and the Economy

        Nutrient pollution and, more specifically, harmful algal blooms have caused significant effects not only to the environment, but also human quality of life and the local economy. Red tide (Karenia brevis) produces brevetoxins that cause respiratory illness and irritation of the skin and eyes in humans, in addition to death in some marine life (Florida Department of Health, 2019). Blue-green algal blooms (cyanobacteria) produce cyanotoxins that cause skin rash, sore throat, headache, nausea, vomiting, diarrhea, and pneumonia in humans (U.S. EPA, 2019). Economic impacts have been experienced in recreational and commercial fishing, real estate, resource management, and the tourism industry. In 2016, 54 businesses reported economic damage related to harmful algal blooms in central and South Florida (Turner, 2016). Future impacts to the local economy are predicted. According to Hazen and Sawyer (2020), “as the environmental quality of the Indian River Lagoon deteriorates, so too will its economic value” (sec. 2). Finally, waterfront property values are expected to decrease by 25% in the next five years if the lagoon is not restored (Tetra Tech, Inc. & Closewaters, LLC, 2020).

Societal and Political Reactions

        Ecological decline of the Indian River Lagoon generates public concern. Economic impacts in particular drive societal awareness. Environmental movements, protests, ad campaigns, and organizations, such as the Marine Resources Council, the Save Our Indian River Lagoon Citizen Oversight Committee, and Captains for Clean Water, are examples of societal reaction to the issue. Public and economic pressure drives political involvement. In 2016, residents of Brevard County (holding the largest portion of the lagoon) voted to raise sales tax by a half-cent for 10 years, totaling approximately $494 million for the Save Our Indian River Lagoon (SOIRL) Trust Fund to be used for lagoon restoration. This year on March 10, Brevard County commissioners voted on an updated plan to assign an additional $55.5 million to restoration projects (Berman, 2020).


        Decades of nutrient pollution in the Indian River Lagoon will likely take decades to remediate. Loss of the Indian River Lagoon would be devastating to the 4,300 species, including 53 threatened or endangered, that reside there (IRL National Estuary Program, 2020). Possible solutions to restore water quality to the IRL include oyster bars, muck removal, mangrove planting, biochar filtration, and monitoring total maximum daily loads (TMDLs).

Oyster Bars
        Oysters are filter feeders, filtering about 50 gallons of water per day. As the oyster filters water to feed, nitrogen is absorbed into its shell and tissue. Nitrogen is then removed by denitrification or by harvesting the oysters. Denitrification is a process by which nitrogen is converted into its gaseous state and released into the air (Bernhard, 2010). Unfortunately, the effects can be localized. However, this solution can also help prevent soil erosion and promote seagrass growth (Tetra Tech, Inc. and Closewaters, LLC, 2020). Oyster bars are sustainable because of its use of natural processes of filtering water. Juvenile oysters also propagate on top of old oyster shells. This solution is currently being implemented by various parties.

Muck Removal
        Muck, containing legacy loads of nutrients, can be removed from the bottom of the Indian River Lagoon for immediate results (Tetra Tech, Inc. & Closewaters, LLC, 2020). This solution uses pumps to siphon muck from the bottom of the lagoon. Muck dredging is currently being implemented using money allocated from the SOIRL Trust Fund.

Mangrove Planting
        Three species of mangroves are native to the Indian River Lagoon: red, black, and white. These mangroves are essential components of the lagoon, providing food and habitat to many land and marine organisms as well as help to stabilize sediments and prevent shoreline erosion. Mangroves can uptake nutrients through the roots which grow out of the water. However, it should be noted that according to Agraz-Hernández et al. (2018), continuous inflows of nutrients could diminish mangroves capability to absorb nutrients. Mangrove planting is currently being accomplished by the Marine Resources Council.

Biochar Filtration
        Biochar is made from burning organic material from agricultural and other wastes with access to very little oxygen. Biochar has a large surface area and is highly porous and can adsorb excess nutrients passing over it (Vikrant et al., 2018). After filtering nutrients from the water, the used biochar has the potential to be reused as fertilizer. Large-scale production of biochar is expensive, however as a small-scale restoration project, this solution could be implemented quickly and relatively inexpensively.

Total Maximum Daily Loads (TMDLs)
        Each state is required by the Clean Water Act to submit a list of impaired and threatened waters and set priorities to develop total maximum daily loads of pollutants. Defined by the EPA (2018), “a TMDL is the calculation of the maximum amount of a pollutant allowed to enter a waterbody so that the waterbody will meet and continue to meet water quality standards for that particular pollutant” (para. 1). The process to set TMDLs is tedious and expensive. Unfortunately, most states do not have enough money or personnel to monitor a large percentage of waterways enough to find problems (Manuel, 2014).

Personal Impact

        Many factors contribute to nutrient pollution of the Indian River Lagoon. Fertilizer use, leaking septic systems, and stormwater runoff are some individual sources of excess nutrient loads. To reduce contributing to the issue, you can discontinue the use of fertilizer on residential lawns. Ensure adherence to the Brevard County fertilizer ban from June 1 through September 30. Another option is to gradually replace your lawn with Florida-native plants, trees, and grasses that require much less maintenance. Additionally, ensure that all grass clippings are blown off the street and back into your yard. Rain barrels can be used to collect rainwater; this creates less runoff and the collected rain can be used to water plants. Encourage others to follow these basic steps, advocate for lagoon restoration at county commission meetings, and volunteer with local non-profit organizations that work to improve the health of the lagoon.

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Harbor Branch Oceanographic Institute. (n.d.). Indian River Lagoon – Facts & figures. Florida Atlantic University.
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Treadway, T. (2018, July 20). Toxic blue-green algae returns to St. Lucie River; bloom now seen in Indian River Lagoon. TcPalm.
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Agraz-Hernández, C.M., del Río-Rodríguez, R.E., Chan-Keb, C.A., Osti-Saenz, J., & Muñiz-Salazar, R. (2018, March). Nutrient removal efficiency of Rhizophora mangle (L.) seedlings exposed to experimental dumping of municipal waters. Diversity, 10(1), 16. 10.3390/d10010016
Vikrant, K., Kim, K., Ok, Y.S., Tsang, D.C.W., Tsang, Y.F., Giri, B.S., and Singh, R.S. (2018, March). Engineered/designer biochar for the removal of phosphate in water and wastewater. Science of the Total Environment, 616-617, 1242-1260.
United States Environmental Protection Agency. (2018, September 13). Overview of total maximum daily loads (TMDLs). Retrieved from
Manuel, J. (2014, November). Nutrient pollution: A persistent threat to waterways. Environmental Health Perspectives, 122(11), A304-A309.

Josh Bailey

Hi, I'm Josh. I like turtles.

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