A coalition of Maryland environmental groups is asking a Baltimore County judge to strike down or overhaul a state stormwater permit they say is too weak to curb industrial pollution flowing into the Chesapeake Bay.

Five organizations, including the Chesapeake Bay Foundation and Blue Water Baltimore, argued Tuesday before a circuit court judge that the Maryland Department of the Environment’s industrial stormwater permit, known as 20-SW, relies on outdated science and vague standards that fall short of protecting water quality.

The case centers on whether the state’s permit for more than 1,000 industrial sites across Maryland sets enforceable limits strong enough to address runoff that carries sediment, heavy metals and other pollutants into the Bay and its tributaries.

“This may be the single most important pollution permit issued by the State of Maryland,” said Evan Isaacson, senior attorney for the Chesapeake Legal Alliance, which represents Blue Water Baltimore and Gunpowder Riverkeeper. He said the permit is “unlawfully weak” and harmful to public health and waterways.

Detailing the argument

The groups argue the permit, first issued in 2022 and revised in February 2025 after an earlier legal challenge, still fails to require meaningful pollution controls. They say it improperly allows continued discharge from industrial “impervious” surfaces and does not adequately account for heavier rainfall tied to climate change.

Stormwater runoff is a leading source of Chesapeake Bay pollution, carrying contaminants from paved and developed areas where rain cannot naturally filter through soil and vegetation.

The state, represented by the Maryland Department of the Environment, defended the permit in court filings, saying stormwater pollution is “diffuse, variable, and difficult to control,” and depends on rainfall, industry type and discharge location.

“This is a strong permit that fully complies with all state and federal laws to protect the Chesapeake Bay and local waterways,” said MDE spokesman Jay Apperson. “The permit addresses climate change by requiring facilities to manage the increasingly heavy and unpredictable runoff caused by extreme weather.”

The agency said the permit requires facilities to minimize pollutant exposure, apply best management practices and monitor compliance using benchmarks rather than strict numeric limits. It argued that approach reflects the absence of federal Environmental Protection Agency standards for this type of discharge.

MDE also said its permit covers more than 1,000 facilities across 34 industrial sectors and is designed to be flexible enough to account for differing site conditions.

Groups argue stronger oversight needed

The environmental groups contend that flexibility amounts to lax oversight. Abel Russ, acting director of law and policy at the Environmental Integrity Project, said the permit fails to require adequate treatment or monitoring.

“Industrial stormwater has high concentrations of toxic metals, organic chemicals, and other pollutants, yet Maryland’s permit is very hands-off,” Russ said. “Virtually no wastewater treatment is required, and there is very little monitoring.”

The petition also claims the revised permit removes or weakens requirements related to reducing untreated impervious surfaces, a charge the state disputes. MDE called that interpretation “factually erroneous,” saying the updated permit maintains and expands prior requirements.

Gunpowder Riverkeeper’s Theaux Le Gardeur said limited state inspections compound the problem, citing what he described as infrequent site visits in several watershed areas.

“This gap in inspections is akin to a ‘see no evil’ stance,” he said, arguing the lack of oversight leaves the public without clear evidence of compliance.

Blue Water Baltimore’s Baltimore Harbor waterkeeper Alice Volpitta also raised environmental justice concerns, saying the permit affects communities already burdened by pollution and climate impacts.

“This one permit covers nearly 300 facilities in the Baltimore region,” Volpitta said. “The consequences of weak standards will have ripple effects.”

The state challenges the argument

MDE said the revised permit is stronger than its predecessor, pointing to benchmark monitoring requirements and mandates that facilities meet those benchmarks. The agency added in Tuesday’s filings that it’s addressing climate change’s effects on stormwater management through regulatory rulemaking outside of the permit process.

The judge in the case is expected to rule in the next several months.

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