Report on Wastewater Management and its Impact on Coastal Ecosystems in the Florida Keys

Introduction

This report details the findings of a Penn State University study on the efficacy of shallow wastewater injection in South Florida, with a specific focus on nitrogen and phosphate contamination. Coastal communities frequently target nitrogen from agricultural runoff and human waste to prevent harmful algal blooms that disrupt marine ecosystems. The study evaluates the environmental impact of injecting treated wastewater into porous limestone bedrock, a common practice in the Florida Keys, and assesses its alignment with key sustainability objectives.

Research Methodology and Key Findings

The research was conducted in the Florida Keys National Marine Sanctuary near a wastewater treatment facility in Marathon, Florida. The facility injects effluent 60 to 90 feet below ground. Scientists analyzed samples from groundwater wells located between the injection site and the coastlines of Florida Bay and Boot Key Harbor from 2021 to 2023.

• Incomplete Contaminant Removal: While underground microbes convert a significant portion of wastewater-derived nitrate and phosphate, the process is not fully effective. Appreciable levels of these nutrients were found to have migrated toward the shore.
• Temporal Variability: The concentration of remaining contaminants in the groundwater fluctuated significantly over time, with variations described as being “by orders ofmagnitude.” This variability is likely tied to seasonal differences in wastewater volume.
• Legal Equivalence: The study concluded that this method of shallow injection is not the “functional equivalent” of direct discharge into the ocean, as the underground transit provides significant, albeit imperfect, filtration.

Implications for Sustainable Development Goals (SDGs)

The study’s findings have direct relevance to several United Nations Sustainable Development Goals, providing critical data for achieving global sustainability targets.

1. SDG 14: Life Below Water: The research directly addresses Target 14.1, which aims to prevent and significantly reduce marine pollution from land-based activities, particularly nutrient pollution. By quantifying the leakage of nitrogen and phosphate into a National Marine Sanctuary, the study underscores the threat to vulnerable marine ecosystems and the urgent need for improved waste management to protect biodiversity.
2. SDG 6: Clean Water and Sanitation: The report contributes to Target 6.3, focused on improving water quality by reducing pollution and minimizing the release of hazardous materials. The evaluation of the shallow injection technique provides crucial evidence on its limitations, informing strategies for more effective wastewater treatment and management to protect receiving water bodies.
3. SDG 11: Sustainable Cities and Communities: The findings are pertinent to Target 11.6, which calls for reducing the adverse per capita environmental impact of cities, including waste management. The case of Marathon, Florida, illustrates the challenge coastal communities face in managing waste sustainably and highlights how scientific research can guide infrastructure decisions toward more environmentally sound solutions.

Policy Implications and Recommendations

The research provides a scientific basis for policy decisions regarding wastewater disposal. Following a 2020 U.S. Supreme Court ruling on discharges into navigable waters and influenced by preliminary data from this research initiative, the Marathon City Council has agreed to phase out shallow injection wells. However, the financial burden of transitioning to alternative methods remains a significant challenge for municipalities.

Based on the findings, the following recommendations are proposed:

• To improve filtration, effluent may require more travel time and distance from the injection point to coastal waters.
• Further research should explore modifying the effluent’s chemical makeup, such as increasing its salinity and density, to slow its ascent to the surface and allow for more thorough natural filtration.
• Continued investment in research is necessary to understand complex biogeochemical processes, such as the adsorption of phosphate to carbonate bedrock, to develop more effective and sustainable long-term solutions.

Analysis of Sustainable Development Goals in the Article

1. Which SDGs are addressed or connected to the issues highlighted in the article?

• SDG 6: Clean Water and Sanitation
• SDG 14: Life Below Water
• SDG 11: Sustainable Cities and Communities

2. What specific targets under those SDGs can be identified based on the article’s content?

1. Target 6.3: By 2030, improve water quality by reducing pollution, eliminating dumping and minimizing release of hazardous chemicals and materials, halving the proportion of untreated wastewater and substantially increasing recycling and safe reuse globally.

   The article directly addresses this target by examining the effectiveness of a wastewater treatment method in South Florida. It discusses how communities dispose of “treated wastewater” containing “nitrate” and “phosphate” through shallow injection. The research finding that “appreciable nitrogen and phosphorous had migrated toward the shore” indicates that this method contributes to pollution, failing to fully improve water quality before the effluent reaches coastal waters. The entire study is an evaluation of reducing pollution from wastewater.

2. Target 14.1: By 2025, prevent and significantly reduce marine pollution of all kinds, in particular from land-based activities, including marine debris and nutrient pollution.

   This target is central to the article. The research focuses on “nutrient pollution” (nitrogen and phosphate) originating from a “land-based” source (wastewater injection wells). The article explicitly states that nitrogen’s “abundance leads to a surplus of algal blooms, upsetting delicate balances of plant and marine life.” The study was conducted in the “Florida Keys National Marine Sanctuary,” where officials are concerned with “hazards to ecosystems already at risk,” highlighting the direct link between the land-based pollution and its impact on marine life.

3. Target 11.6: By 2030, reduce the adverse per capita environmental impact of cities, including by paying special attention to air quality and municipal and other waste management.

   The article discusses how “seaside communities,” specifically Marathon, Florida, manage their municipal waste—in this case, “treated wastewater.” The practice of shallow injection is presented as a waste management strategy with adverse environmental impacts, as it is “not 100% efficient” and injects “contaminants into the ecosystem.” The decision by the “Marathon City Council… to shift away from shallow injection” due to an environmental lawsuit demonstrates a city-level effort to reduce its environmental impact by improving its waste management system.

3. Are there any indicators mentioned or implied in the article that can be used to measure progress towards the identified targets?

1. Indicator for Target 6.3: Concentration of nitrogen (nitrate) and phosphorous (phosphate) in groundwater and nearshore waters.

   The article explicitly mentions the measurement of these pollutants. Researchers drew “samples from an array of groundwater wells” and found that “contaminant levels shifted widely over time.” They measured how much “nitrate and phosphate had already been removed from the water, or still remained,” which serves as a direct indicator of water quality and the effectiveness of the wastewater treatment process before it reaches other water bodies.

2. Indicator for Target 14.1: Level of nutrient pollution from land-based wastewater injection entering coastal marine ecosystems.

   The study’s primary goal was to quantify the extent of this pollution. The article states that researchers “consistently found appreciable nitrogen and phosphorous had migrated toward the shore,” directly measuring the flow of land-based nutrients into the marine environment. The mention of nitrogen’s role in causing “algal blooms” implies that the presence of these nutrients is an indicator for coastal eutrophication, a key component of measuring marine pollution.

3. Indicator for Target 11.6: Effectiveness and environmental safety of municipal wastewater management practices.

   The article implies this indicator through its evaluation of the shallow injection method. The research concluded that the injections “aren’t equal to direct discharges” but are also “not 100% efficient.” The subsequent decision by the city of Marathon to “shift away from shallow injection” because of its environmental impact is a qualitative measure of progress towards adopting safer and more effective waste management systems.

SDGs, Targets, and Indicators Summary

Source: psu.edu