Emerging contaminants (ECs) in Maryland’s stormwater are a growing threat to water quality, aquatic life, and human health. These include PFAS ("forever chemicals"), 6PPD-quinone (from tire wear), microplastics, and heavy metals, which often bypass traditional water treatment systems. Here’s a quick summary of the key issues:

• PFAS: Found in 85% of Maryland’s public water systems, with levels exceeding EPA’s 2024 safety limit of 4 ng/L.
• 6PPD-quinone: Linked to fish toxicity, especially in urban streams.
• Microplastics: Up to 24.6 particles per liter in stormwater, largely from tire and road wear.
• Heavy Metals & Chloride: Sources include vehicle emissions and road salt, with chloride levels rising significantly over decades.

These pollutants harm ecosystems and drinking water, requiring advanced filtration like granular activated carbon (GAC), biochar filters, and membrane systems. Maryland is tackling the issue through state regulations, local projects, and private-sector solutions like Pro Landscapes MD, which integrates stormwater management into property-level designs.

The challenge is large, but with combined efforts from government, communities, and businesses, Maryland can mitigate the impact of these contaminants on its waterways and public health.

Biochar & Nature Based Solutions for PFAS in Stormwater Management in the Age of Climate Change

Main Emerging Contaminants in Maryland Stormwater

Maryland’s stormwater carries a mix of pollutants that pose serious risks to water quality and local ecosystems. Recent research highlights several types of emerging contaminants in the state’s urban and suburban watersheds. These pollutants, ranging from newly identified chemicals to long-standing issues, add complexity to Maryland’s ongoing water management challenges.

Per- and Polyfluoroalkyl Substances (PFAS)

PFAS, often referred to as "forever chemicals", are a persistent presence in Maryland’s stormwater. These compounds resist natural breakdown and build up over time in surface and groundwater. Key sources include industrial sites, airports using firefighting foam, and everyday consumer products. In the Chesapeake Bay region, urban and agricultural areas contribute differently to PFAS levels. Urban areas, with their concentrated industrial and consumer activities, tend to have higher PFAS concentrations, presenting a tough problem for standard water treatment processes ^[8].

6PPD-Quinone and Tire-Derived Compounds

Tire wear particles release harmful chemicals like 6PPD-quinone into Maryland’s stormwater. This compound, a byproduct of the tire preservative 6PPD, is toxic to fish like salmon even at very low levels. Studies link urbanization and dense road networks to increased 6PPD-quinone concentrations in local streams ^[3]. For instance, during an October 2022 storm in Washington’s Thornton Creek Watershed, 6PPD-quinone was found in 29% of composite samples (0.002–0.010 μg/L) and 86% of discrete samples (0.002–0.085 μg/L) ^[6].

Microplastics and Tire Rubber Fragments

Microplastics, including fragments from tire rubber, are becoming a growing concern in Maryland’s stormwater. Concentrations of microplastics in stormwater range from 1.1 to 24.6 particles per liter ^[5]. Notably, fibers and black rubbery fragments – likely from tire and road wear – make up about 85% of the microplastics detected ^[5]. Land use also plays a role: industrial areas show a strong link to higher microplastic levels (p < 0.001, R² = 0.72), and areas with more impervious surfaces see increased concentrations (p < 0.01, R² = 0.65) ^[5]. These surfaces allow microplastics to accumulate and be swept into waterways during rainstorms ^[3][4].

Heavy Metals and Chloride

Traditional pollutants, like heavy metals and chloride, continue to strain Maryland’s waterways. Metals such as lead, zinc, and copper enter streams through vehicle emissions, brake wear, construction materials, and industrial runoff. During storms, these pollutants wash off impervious surfaces and into water bodies. Chloride, largely from winter road salt, has also surged in recent decades, with levels in the Potomac River rising by 41% and in the Patuxent River by 102% over 30 years ^[7]. Chloride concentrations above 50 mg/L can stress freshwater aquatic life.

Despite efforts, Maryland has seen no measurable reduction in stormwater pollution between 2009 and 2023 ^[9]. Meanwhile, rainfall has increased by 2.63 inches per decade between 2000 and 2020, exacerbating the problem ^[9].

Effects of Emerging Contaminants on Maryland’s Ecosystems

Emerging contaminants carried by stormwater in Maryland are disrupting ecosystems, threatening wildlife, and posing serious risks to human health. These pollutants, often unnoticed, are having far-reaching effects on both aquatic life and local communities.

Aquatic Life and Biodiversity

Maryland’s waterways are increasingly burdened by pollutants that enter through stormwater runoff. Among these, tire-derived compounds are a major concern. One such compound, 6PPD-quinone, is formed when tire preservatives break down. This chemical has been shown to be lethal to sensitive fish species. A 2021 study by Tian et al. highlighted its deadly effects on coho salmon and other salmonids, linking the problem to particles from tire wear in urban runoff ^[1].

Microplastics from tire wear further worsen the situation. These tiny particles, both physical and chemical hazards, have been found in alarming quantities. For instance, untreated stormwater samples from San Francisco Bay watersheds revealed up to 15.9 tire particles per liter, accounting for nearly half of all measured microparticles ^[1]. This sheds light on tire wear as a significant global source of microplastics.

Another persistent issue is contamination from PFAS – often called "forever chemicals." These substances do not break down in the environment and tend to accumulate in aquatic organisms. Over time, they can interfere with reproduction, immune systems, and growth rates, creating long-term challenges for ecosystems.

The ripple effects of these ecological disruptions extend to human communities, making the health risks posed by these contaminants impossible to ignore.

Human Health and Water Safety

Stormwater runoff doesn’t just harm aquatic ecosystems – it also threatens the safety of drinking water. Maryland residents face exposure to these pollutants through drinking water sources and recreational activities. Public water systems serve 5.1 million Maryland residents, while over a million rely on private wells ^[10]. Studies have found microbiological contaminants, such as total coliforms and E. coli, in both public and private water supplies. Additionally, PFAS has been detected in about 1.3% of public drinking water systems ^[10].

Maryland’s 463 public water utilities, serving 5.431 million people, have identified 94 contaminants exceeding health guidelines. These include total trihalomethanes, haloacetic acids, radium, and bromodichloromethane ^[14]. The long-term exposure to PFAS, even at low levels, has been linked to serious health issues such as cancer, thyroid problems, and weakened vaccine responses ^[12]. Nationwide, over 143 million people are exposed to PFAS in their drinking water, and these chemicals have been found in nearly every American’s blood – even in newborns ^[14].

Recreational water is another area of concern. Urban runoff often contains fecal coliform bacteria levels 20 to 40 times higher than the safe standard for swimming ^[13]. The EPA has estimated that waste from just 100 dogs over a single weekend can carry enough bacteria to shut down a bay for swimming and shellfishing ^[11].

Adding to the problem, industrial and agricultural pollutants like organic compounds and heavy metals exacerbate water quality issues. Industrial chemicals such as trichloroethylene, perchloroethylene, and benzene are linked to cancer, liver damage, and neurological harm ^[14]. Heavy metals like arsenic and hexavalent chromium, which have been detected in drinking water, are also associated with cancer and organ damage ^[14].

Compounding the issue, stormwater often bypasses wastewater treatment systems, allowing pollutants from urban surfaces like roads and parking lots to flow directly into rivers, streams, and bays. These bodies of water are critical for both drinking and recreation ^[11]. In rural areas, nitrates from farm runoff and wastewater pose additional risks, particularly to infants and pregnant women relying on private wells.

The cumulative impact of these contaminants is staggering. Radiological substances such as radium and uranium have been linked to neurological disorders, developmental delays, organ damage, and increased cancer risk ^[14]. For instance, the Environmental Working Group analyzed data from nearly 50,000 water systems between 2021 and 2023, identifying 324 contaminants in drinking water supplies across the nation ^[14].

Filtration Technologies for Removing Emerging Contaminants

Maryland’s stormwater systems rely on advanced filtration technologies to tackle emerging contaminants like PFAS, microplastics, and heavy metals. These systems are critical for protecting waterways and drinking water supplies. Here’s a closer look at some of the key filtration methods and how they perform in addressing Maryland’s unique stormwater challenges.

Granular Activated Carbon (GAC) and Biochar Filters

Granular activated carbon (GAC) is a widely used method for removing organic contaminants from water. Its porous structure traps pollutants through adsorption, making it particularly effective for eliminating long-chain PFAS. Over the past 15 years, GAC has been utilized at more than 45 military installations, as well as industrial sites and public treatment facilities ^[15].

While GAC excels at removing long-chain PFAS, it struggles with shorter-chain variants ^[15]. The effectiveness of GAC depends heavily on system design, as different PFAS compounds vary in their loading capacities and breakthrough times ^[15]. Research conducted in Colorado further highlighted how breakthrough behavior shifts depending on PFAS chain length, though exceptions exist ^[18].

Biochar filters, made from organic materials like wood chips or agricultural waste, offer a more budget-friendly alternative to GAC. Biochar costs range from US$350 to US$1,200 per metric ton compared to GAC’s US$1,100 to US$1,700 per metric ton ^[19]. However, the performance of biochar can vary significantly depending on the feedstock and production process ^[19]. A notable initiative funded by a US$1.4 million grant is exploring modular stormwater treatment systems using wood chips and compost to capture contaminants like PCBs, PAHs, and copper ^[17].

Both GAC and biochar systems require consistent maintenance. GAC regeneration, for instance, is energy-intensive and can be affected by natural organic matter ^[18].

Engineered Media and Membrane Filtration

Engineered media systems represent a newer approach to stormwater treatment. Abtech Industries’ Smart Sponge® technology, for example, has shown significant advantages over traditional GAC and resin systems. This technology delivers flow rates of up to 40 GPM/SF with contact times as short as 45 seconds, minimal back pressure (<1 PSI), and low moisture levels, making it highly efficient ^[16].

Membrane filtration systems, such as nanofiltration (NF) and reverse osmosis (RO), remove PFAS through size exclusion thanks to their small pore sizes. However, these systems are energy-intensive and generate concentrated waste. The EPA has set strict contamination limits for PFAS in drinking water – 4.0 parts per trillion for PFOA and PFOS, and 10 parts per trillion for PFNA, PFHxS, and HFPO-DA ^[18].

Ion exchange (IX) systems use specialized resins to achieve high PFAS removal rates, though they come with higher costs. Pilot studies have shown that single-use resins can remove long-chain PFCAs and PFSAs up to eight times more efficiently than regenerable resins. The cost of media for IX systems ranges from US$256 to US$322 per cubic foot ^[18].

Filtration Technology Comparison

Each filtration method offers unique strengths and limitations, making it essential to choose the right technology for specific stormwater management needs. Here’s a comparison of some of the key options:

A study highlighted the cost challenges of GAC systems:

"The costs for GAC regeneration typically account for the majority of the yearly operating costs. Belkouteb et al. demonstrated that by adjusting the flowrates to prolong the lifespan of the GAC filters can reduce the costs by 26%. Further, reducing the regeneration costs by 20% also lowers the unit cost by 20%" ^[18].

Given Maryland’s high rainfall and diverse contaminant profile, combining multiple filtration methods in series can enhance overall removal efficiency. While this approach may increase upfront costs, it often delivers better long-term results, making it a viable strategy for integrated stormwater management ^[15].

sbb-itb-843f8be

Maryland Implementation and Local Practices

Maryland has taken a proactive approach to managing emerging contaminants through a mix of integrated stormwater management strategies and state-level oversight. By combining advanced filtration systems with broader environmental initiatives, the state addresses both traditional pollutants and newer, less understood contaminants.

The Maryland Department of the Environment (MDE) plays a central role in regulating stormwater management. It oversees filtration technologies and administers MS4 permits to ensure compliance. Maryland’s stormwater quality regulations align with Section 6217(g) of the Coastal Zone Management Reauthorization Act of 1990, aiming for an average 80% reduction in Total Suspended Solids (TSS) ^[23]. While the focus in the 1990s was primarily on controlling water quantity, concerns about water quality – including emerging contaminants – soon took center stage ^[23].

To encourage effective stormwater treatment, Maryland employs a Best Management Practice (BMP) credit system. This system rewards municipalities and private developers for adopting proven filtration technologies, fostering widespread use of advanced solutions like the StormFilter, which has been approved by the MDE ^[22].

Local municipalities are also stepping up to improve stormwater infrastructure. The City of Annapolis has become a standout example, implementing projects that address both traditional stormwater concerns and emerging pollutants. In 2025, the city completed a restoration project at the Roger "Pip" Moyer Recreation Center on Hilltop Lane. This included sediment removal, invasive species control, mulching, and planting native vegetation ^[20].

Another noteworthy project took place at the Masjid Al-Ansar mosque, where outdated bioretention facilities were rehabilitated in 2025. Crews replaced stone and turf with proper planting materials and new vegetation. This effort also involved the Maryland Reentry workforce, showcasing how stormwater management can align with community development initiatives ^[20].

Looking ahead, Annapolis is preparing to launch a pilot cost-share grant program in 2026. This program will help property owners maintain stormwater facilities, with a particular emphasis on supporting economically disadvantaged neighborhoods ^[20]. Additionally, the Maryland State Highway Administration (SHA) recently secured a new MS4 permit from MDE to address highway runoff pollution ^[21].

"Implementing effective stormwater controls is crucial for enhancing community resilience and environmental stewardship. These systems can help mitigate flooding – and protect vital infrastructure – by managing excess rainwater. They also improve water quality in nearby creeks and rivers by filtering pollutants from stormwater runoff. It’s all part of our goal to be good stewards of the land and local waterways." – Roslyn Johnson, Recreation and Parks Director ^[20]

This collaboration between state and local efforts underscores the importance of property-level solutions in improving overall stormwater quality.

Pro Landscapes MD‘s Role in Stormwater Solutions

While state and local governments drive large-scale initiatives, property-level solutions are essential for intercepting pollutants before they enter larger waterways. Pro Landscapes MD plays a key role in implementing Maryland’s stormwater strategies at this level, offering tailored solutions that align with the state’s goals for managing emerging contaminants.

Pro Landscapes MD specializes in designing custom drainage systems that not only direct water away from properties but also integrate filtration to capture contaminants. Their services include installing French drains, swales, berms, box and pipe systems, regrading, and sump pumps. These solutions can be paired with advanced filtration technologies to maximize their effectiveness ^[24].

The company’s emphasis on eco-conscious designs complements Maryland’s regulatory framework, prioritizing sustainable practices that protect water quality. For example, their use of environmental pavers helps reduce stormwater runoff while enabling natural filtration processes. This approach not only addresses water quality concerns but also supports healthier ecosystems.

"At Pro Landscapes MD, we specialize in creating outdoor environments that blend beauty, function, and sustainability." – Pro Landscapes MD ^[24]

Pro Landscapes MD also incorporates bioretention facilities and rain gardens into their landscape designs. These systems are particularly effective for filtering emerging contaminants while maintaining aesthetic appeal. By using specialized filtration media and ensuring proper grading and land leveling, the company ensures these systems remain functional and efficient over time ^[24].

Their comprehensive service model – from planning and installation to ongoing maintenance – tackles one of the biggest challenges in stormwater management: maintaining long-term system performance. Serving communities across central Maryland, including Howard, Montgomery, Carroll, Frederick, Prince George’s, and Baltimore counties, Pro Landscapes MD is well-positioned to support both urban and suburban stormwater management efforts.

Conclusion: Managing Emerging Contaminants in Maryland Stormwater

Addressing emerging contaminants in Maryland’s stormwater systems requires both urgency and a long-term commitment. Pollutants like PFAS compounds, tire-derived chemicals, microplastics, and heavy metals pose serious risks to aquatic life and human health throughout the state. These contaminants are not just environmental concerns – they directly impact the well-being of Maryland’s ecosystems and communities.

Advanced filtration technologies offer promising solutions. For instance, systems like the StormFilter, which use rechargeable, media-filled cartridges, have shown success in targeting specific pollutants while remaining cost-efficient^[22]. Similarly, research from the University of Maryland highlights the potential of enhanced bioretention systems, forecasting a 75% improvement in nitrogen removal^[26].

"Runoff from urban development represents a growing source of pollution to the Chesapeake watershed, and we believe we can help curb this",
– Allen P. Davis, University of Maryland professor of Civil and Environmental Engineering^[26]

Such innovations must work hand-in-hand with state and local strategies for long-term impact.

Beyond technology, a coordinated framework involving regulation and community action is essential. On-the-ground solutions, like property-level drainage systems, help reduce erosion, control flooding, and improve water quality while safeguarding local wildlife^[25][27]. Companies like Pro Landscapes MD play a vital role by integrating practical drainage solutions with regulatory requirements, ensuring compliance and effectiveness.

As Maryland moves forward with its stormwater management efforts, collaboration will be key. Researchers, regulators, and practitioners must work together to implement solutions that address contamination at its source. This includes applying green chemistry principles to design safer chemicals, leveraging technology to detect and eliminate pollutants, and fostering public education to build awareness^[2]. Maryland’s blend of state oversight, community involvement, and private sector innovation offers a strong model for tackling these challenges.

Through sustained research, thoughtful regulation, and practical action, Maryland can protect its waterways for generations to come, ensuring a healthier future for all its communities.

FAQs

What are the main sources of PFAS in Maryland’s stormwater, and why are they so challenging to remove?

Sources of PFAS in Maryland’s Stormwater

In Maryland, PFAS (per- and polyfluoroalkyl substances) often find their way into stormwater from several key sources. These include wastewater treatment plants, landfills, emissions from industrial facilities, and areas where firefighting foams (AFFF) are used, such as airports. These substances contaminate stormwater runoff by seeping into the soil, water, and even the air.

What makes PFAS particularly challenging to manage is their persistence in the environment. They don’t break down easily and can linger for long periods, accumulating in water systems and even in living organisms. Traditional filtration and treatment methods struggle to remove them completely because of their unique chemical structure. Tackling PFAS contamination often requires advanced solutions like activated carbon filters or reverse osmosis systems, which are designed to handle these stubborn compounds more effectively.

What impact do emerging contaminants like 6PPD-quinone and microplastics have on Maryland’s aquatic life and ecosystems?

Emerging contaminants like 6PPD-quinone and microplastics are taking a toll on Maryland’s aquatic life and ecosystems. 6PPD-quinone, a chemical found in tire wear particles, is especially harmful to fish. It’s known to cause acute mortality in species such as coho salmon and other aquatic organisms exposed to stormwater runoff. This chemical not only endangers individual species but also disrupts entire ecosystems, posing a serious threat to biodiversity.

Microplastics – those tiny plastic fragments that end up in waterways – are another growing concern. Marine organisms often ingest these particles, which can stunt their growth, impair reproduction, and shorten their lifespan. Worse, microplastics can carry harmful chemicals up the food chain, impacting larger species and putting the health of entire ecosystems at risk. These issues underscore the urgent need for better stormwater management and pollution control measures to safeguard Maryland’s waterways and aquatic life.

What cutting-edge filtration technologies are being used in Maryland to tackle emerging contaminants in stormwater?

Maryland is stepping up its efforts to tackle the issue of emerging contaminants in stormwater by using cutting-edge filtration technologies. These include bio-filtration systems, advanced filtration media that go beyond the capabilities of traditional granular activated carbon (GAC), and specialized treatments aimed at removing PFAS, hydrocarbons, and other harmful pollutants.

These technologies are designed to target and reduce a wide range of contaminants, such as pharmaceuticals, microplastics, nutrients, and hydrocarbons. By implementing these solutions, Maryland is making strides to safeguard its waterways and ecosystems while addressing the ongoing challenges of stormwater pollution.

Related posts

• 5 Cost-Effective Stormwater Solutions for Maryland Homes
• Top SWPPP Practices for Maryland Sites
• Permeable Pavers for Stormwater Control in Maryland
• Phosphorus Filters in Maryland Stormwater Systems