Impact of Fertilizer Pollution on Biscayne Bay

Excess fertilizer in Biscayne Bay can kill seagrass, cause algae blooms, and turn clear water cloudy and green or brown, harming marine life. This can lead to fish kills, starving manatees, and the destruction of ecosystems. These ecosystems protect us from the effects of rising sea levels.

So what can you do?

Slow-release fertilizer used in Miami

Your efforts will lead to:

  • Cleaner, clearer water.
  • A vibrant Biscayne Bay.
  • Better water quality for residents and tourists.
  • Healthier manatees.
  • A more stable, secure ocean economy.
  • Resilience against sea level rise.
  • Maintained home values.
  • Thriving urban areas.
  • The satisfaction of doing your part for the environment.

What is Fertilizer?

Fertilizer is plant food that primarily provides nitrogen and phosphorus, which roots can easily absorb. The agriculture industry and farmers apply it to grow food and support residential and commercial landscaping.

Researchers estimate that residential lawn fertilization is a major source of nitrogen in U.S. households, second only to sewage (Souto et al., 2019).

How Can Fertilizer Cause Pollution?

Fertilizer is a type of nutrient pollution and can damage waterways. Just like fertilizer feeds plants on land, it also feeds vegetation in our waterways. Summer rains often wash fertilizers from lawns into Biscayne Bay before plants can absorb them.

Fertilizer being applied in Miami

Does fertilizer pollute water? Floating in the water are tiny aquatic plants called algae, which eat up fertilizer nutrients. Excessive nitrogen and phosphorus in waterways can lead to algae blooms, which reduce oxygen levels in two ways:

  1. The bloom itself blocks sunlight from reaching other aquatic plants that need it to grow and photosynthesize.
  2. Bacteria decompose these harmful algal blooms after they die. This process consumes a lot of oxygen, which also affects the survival of aquatic life.

Biscayne Bay has lost up to 90 percent of seagrass in some areas! This has resulted in dead zones where oxygen levels are too low in the water for marine life to survive. This has led to several instances of fish kill, or mass deaths of fish and other marine species.

In August 2020, Biscayne Bay experienced an unprecedented fish kill with over 27,000 dead fish on our shores. Two years later, the bay experienced another major fish kill, leading to thousands more dead and dying fish.

Fish kills are increasingly common in August and October due to higher water temperatures and king tides, which stress the bay further.

Biscayne Bay is at a critical tipping point, making it vital to prevent excess nutrients from entering our waterways.

Nutrient pollution comes from fertilizers, septic tanks, sewage, and runoff. Reducing residential fertilizer use is one effective way to improve water quality and keep Biscayne Bay blue.

Journey of fertilizer in Biscayne Bay

Why is Fertilizer Pollution a Problem?

We often answer yes to, "can fertilizers cause water pollution?" That's because Biscayne Bay is a central feature of South Florida. As an economic driver in our region, a healthy bay is essential to our communities. The health of South Florida’s economy, environment, community, history, and culture directly depends on the health of Biscayne Bay.

If we don’t change our fertilizer habits, we risk:

  • The loss of native seagrass habitats in Biscayne Bay.
  • Manatee habitat and ecosystem degradation.
  • The threat of pollution by fertilizers in our waterbodies.
  • Our water-driven economy and livelihoods.
  • More frequent fish kills on our shores.
  • Loss of opportunities for fishing.

We can't risk Biscayne Bay becoming a dead zone.

What Can I Do to Prevent Fertilizer Runoff?

To avoid excess fertilizer runoff, following your local fertilizer ordinance is essential. Miami-Dade County adopted its Florida-Friendly fertilizer use on urban landscapes ordinance in April 2021. The ordinance helps reduce nitrogen and phosphorus in our waterways and enhances Biscayne Bay's health.

This ordinance includes the following regulations:

  1. Skip the fertilizer during the summer rainy season, May 15 – Oct. 31.
  2. Use only phosphorus-free fertilizer.
  3. Use fertilizers that contain at least 65% slow-release nitrogen.
  4. Apply fertilizer at least 20 feet away from storm drains and surface water bodies, such as canals, wetlands, lakes, or the bay.
  5. Manage yard clippings to prevent them from entering stormwater drainage systems or water bodies.
  6. If you apply fertilizers as part of your job, get training on the best management practices (BMPs) that help protect water resources.


Key Terms to Know About Fertilizer Pollution

  • Fertilizer is a substance added to soil or plants to supply necessary nutrients for growth. It typically contains a combination of nitrogen (N), phosphorus (P), and potassium (K), along with other micronutrients. Fertilizers can be organic (derived from natural sources) or inorganic (synthetically produced).
  • Nitrogen (N) is a primary macronutrient vital for plant growth. It is a key component of chlorophyll, which is necessary for photosynthesis. Nitrogen also plays a crucial role in the development of amino acids, proteins, and other vital plant compounds. Plants with sufficient nitrogen exhibit strong, healthy growth and dark green foliage.
  • Slow-release nitrogen is a type of fertilizer that slowly releases nutrients over a long time. This method helps prevent nutrient loss from leaching or volatilization. It also ensures a consistent supply of nitrogen to plants. Slow-release nitrogen sources include organic materials like compost, as well as specially formulated synthetic fertilizers.
  • Phosphorus (P) is another vital macronutrient for plant growth. It plays a key role in root development, energy transfer in plants, and the production of flowers, fruits, and seeds. Phosphorus also aids plants in developing strong stem and root systems, enhancing their overall health and vitality.
  • Potassium (K) is the third primary macronutrient needed for plant growth. Various plant functions depend on it, such as enzyme activation, protein synthesis, and controlling water and nutrient absorption. Potassium also assists plants in developing strong roots, increasing disease resistance, and improving the quality of fruits and vegetables.
  • An algae bloom occurs when there is a rapid rise in the algae population in a water body. This is often due to an excess of nutrients such as nitrogen and phosphorus.

Fertilizer pollution in Miami

Miami Waterkeeper

Miami Waterkeeper works to protect our native ecosystems by advocating for resilient solutions grounded in science, rooted in nature, and driven by community. Specifically, we focus on wetlands, mangroves, seagrasses, and coral reef conservation and restoration.

Miami Waterkeeper protects local ecosystems by promoting science-based, natural, and community-driven solutions. We focus on conserving and restoring wetlands, mangroves, seagrasses, and coral reefs.

What Actions Are We Taking?

Miami Waterkeeper's research and advocacy efforts led to the strongest fertilizer ordinance in Florida, adopted by Miami-Dade County. This initiative also inspired eight municipal ordinances and two county-wide ordinances in Miami-Dade and Monroe counties.

It's crucial people know about these ordinances for them to work well. Do your part to protect Biscayne Bay by learning about and following the guidelines outlined in the fertilizer ordinance.

Participate in Community Clean-Up Events

Volunteering at Miami Waterkeeper’s clean-up events is a direct way to help our waterways. Spend a few hours cleaning up debris, restoring marine habitats, and connecting with fellow environmental enthusiasts. Joining these events builds community and promotes environmental protection.

RSVP Today


Community members cleaning marine debris in Miami