Nitrates

in the Floridan Aquifer

An underwater image of thick, bright green filamentous algae on a wall in Manatee Springs.

Breathe in...

78% of what you just inhaled is nitrogen.

Nitrogen is present in all living things and considered a building block of our DNA.

Without it, life on Earth would not be possible.

To understand nitrogen's impact on the Floridan Aquifer, we must first understand the aquifer itself.

THE FLORIDAN AQUIFER

Divers swim through caves at Peacock Springs as sun shines down from above.

Divers in Peacock Springs, 2018. Photo by John Moran.

KARST (/kärst/)

A landscape underlain by limestone which has been eroded by dissolution.

Much of Florida's geology consists of limerock formations known as karst terrain. Formed 25-60 million years ago when the region was still the sea, Florida's limerock base is composed of fossilized skeletons of marine organisms that have been compressed over time.

A karst landscape is characterized by the presence of sinkholes, springs, and underground streams. These traits are distinctive to karst because they form as [slightly acidic] rainwater percolates down into the aquifer, dissolving soluble limerock as it travels.

Riverbank highlighting the holes and crevices in karst along the Suwannee River.

Karst riverbank along the Suwanee River.

AQUIFER (/äkwəfər/)

A body of permeable rock which can contain or convey groundwater.

The Floridan Aquifer is considered one of the most productive in the world, due to its vast size (100,000 square miles) and the ability of groundwater to travel easily through its porous limerock.

Two children swimming and exploring the caves at Chassahowtizka springs.

Exploring the karst of Chassahowitzka, 2016. Photo by John Moran.

NITRATES IN FLORIDA'S SPRINGS

Many of Florida's water bodies are impaired. The Florida Department of Environmental Protection (FDEP) is required to create plans to identify and reduce the pollutants, including nitrogen. These plans are called  Basin Management Action Plans  (BMAPs).

When creating BMAPs, FDEP assessed the sources of nitrogen loading for each BMAP area. These sources can be broken into three main categories:

  • Development - nitrogen from landscape fertilizers and human wastewater
  • Agriculture - nitrogen from farm fertilizers and livestock waste
  • Atmospheric Deposition - nitrogen from the atmosphere as gases and precipitation

Use the interactive map below to explore springs BMAP areas and their main sources of nitrogen loading.

Click on the BMAP area to learn how they are impacted by development and agriculture.

BMAPs are described by FDEP as "blueprints for restoring impaired waters by reducing pollutant loading..." Unfortunately, many of these plans fall short in the effort to protect Florida's springs.

Springs advocacy groups are challenging five of the BMAPs under the coordination of the  Florida Springs Council .

SANTA FE RIVER BMAP AREA

To learn more about the effects of development and agriculture, we're going to focus on one of the five spring BMAPs being challenged - the  Santa Fe River BMAP . The Santa Fe River BMAP area is located in northern Florida and includes the Santa Fe River, the Ichetucknee River, and dozens of springs.

The Santa Fe River. Photo by Hillary Skowronski

The Santa Fe River BMAP Area

Let's take a closer look at two sources of nitrates: development and agriculture.

THE IMPACTS

Half above water and half below water, Peacock Springs is full of thick, bright green algae.

This image was captured by John Moran at Peacock Springs, in June 2019.

An obvious sign of an unhealthy spring is excessive algae growth.

Algae are plant-like organisms that are naturally found in Florida's aquatic systems. Natural levels of nitrogen help aquatic plants grow.

When groundwater with excessive nitrate levels flows into springs and spring-fed rivers, it can act like fertilizer for algae. This can cause algae to grow and spread more rapidly, especially in areas of low water flow.

A kayak paddle is draped with thick, green filamentous algae and the river surface is covered in algae too.

Algal mats on the Santa Fe River, 2012. Photo by John Moran.

As excessive algae grows, it may form mats at the water’s surface or cover native vegetation underwater, making it difficult for sunlight to reach existing plants.

When vegetation cannot photosynthesize properly, it limits the aquatic food chain and the amount of dissolved oxygen released into the water, making it difficult for aquatic life to thrive.

A diver is underwater at Peacock Springs and it is filled with filamentous algae.

Filamentous algae overgrowth at Peacock Springs. Photo by John Moran.

An underwater view of the Ichetucknee showing thick green aquatic vegetation and white sandy bottom.

This image is of snorkeling with healthy submerged vegetation at Ichetucknee Springs State Park, 2017. Photo by John Moran

If you saw the Ichetucknee River for the first time today, you would invariably be struck by its beauty. But today's Ichetucknee is different than the river once experienced by Archie Carr.

CHANGES IN THE ICHETUCKNEE

For many years the Ichetucknee River and its springs were considered an example of a healthy and thriving spring system. Over time, its water quality has begun to decrease. Increased nitrate levels have contributed to imbalanced algae growth along sections of the river.

An underwater view of people tubing on the Ichetucknee, their legs dangling down into water with algae floating and covering the vegetation.

Ichetucknee River, 2014. Photo by John Moran

An image from 1995 at the Ichetucknee shows clear water and thick green vegetation. On the right is the Ichetucknee in 2012, with a man floating in murky water with mostly algae coating the bottom.

Then and Now on the Ichetucknee, part of the Springs Eternal Project. Photos by John Moran

The Florida Department of Environmental Protection determined that a healthy spring should have a nitrate level of 0.35 mg/L or less.

This graph shows the trend of nitrates increasing from below 0.35 mg/l of NOx-N in the 60s to current levels of almost 80 mg/l of NOx-N. There is a photo of a spring vent in the background.

This graph shows the trend of increasing nitrate levels in the Ichetucknee.  Click here  for a detailed graph. Photo by J.S. Clark

Data collected in the 1960s show that the Ichetucknee was a healthy spring system, with nitrate levels under 0.35 mg/l. Since then, nitrate levels have more than doubled.

Roughly 80% of Florida's 1,000+ freshwater springs exceed the nitrate limit for healthy springs.

Human activities are disrupting the natural balance of nitrates and algae in Florida's spring ecosystems.

The Floridan Aquifer and its springs are an integral part of Florida's natural heritage.

It's not too late to protect them.

Ichetucknee River, 2016. Photo by John Moran

WHAT CAN I DO?

Awareness and understanding are the first steps. The Blue Water Audit was created by the Howard T. Odum Florida Springs Institute to estimate and visualize human impact on the aquifer. Visit the  Blue Water Audit  site to learn more about the aquifer and springs, calculate your aquifer footprint, and explore impacts on the aquifer with the Blue Water Audit Interactive Map.


To learn more about springs science, visit  www.FloridaSpringsInstitute.org 

Cover photo: Manatee Spring, 2013. Wall of Algal Shame by Mark Long

Story map photos: Unless otherwise credited, photos by Florida nature photographer John Moran

3D aquifer models: Haley Moody

Story Map: The Howard T. Odum Florida Springs Institute - Angeline Meeks & Haley Moody

Divers in Peacock Springs, 2018. Photo by John Moran.

Karst riverbank along the Suwanee River.

Exploring the karst of Chassahowitzka, 2016. Photo by John Moran.

The Santa Fe River. Photo by Hillary Skowronski

This image was captured by John Moran at Peacock Springs, in June 2019.

Algal mats on the Santa Fe River, 2012. Photo by John Moran.

Filamentous algae overgrowth at Peacock Springs. Photo by John Moran.

This image is of snorkeling with healthy submerged vegetation at Ichetucknee Springs State Park, 2017. Photo by John Moran

Ichetucknee River, 2014. Photo by John Moran

Then and Now on the Ichetucknee, part of the Springs Eternal Project. Photos by John Moran

This graph shows the trend of increasing nitrate levels in the Ichetucknee.  Click here  for a detailed graph. Photo by J.S. Clark

Ichetucknee River, 2016. Photo by John Moran