With the problem of polluted stormwater washing off highways only projected to get worse with climate change, environmental advocates are calling on the Maryland Department of Transportation to do more to curb it.

One dramatic example of the kind of mitigation they would like the agency to require:

Stormwater runoff controls could be built into the Francis Scott Key Bridge replacement.

“We should be insisting that the Highway Department put in vaults to capture the rainfall runoff that falls onto that bridge deck,” said Doug Myers, senior scientist at the Chesapeake Bay Foundation (CBF).

That way, the runoff “could be channeled into infiltration wetlands at the base of the bridge on either side,” Myers told The Brew, describing roadside bioswales and vegetated filter strips where the runoff could be naturally treated and discharged as rainwater “instead of it just dropping down directly into the harbor.”

The original bridge, which collapsed in March when a container ship struck one of its piers, never had any of these stormwater controls when it was built in 1977 because they weren’t required at that time.

While transportation officials tend to balk at the idea of retrofitting existing infrastructure with such improvements, Myers said, they would have a chance to incorporate best practices from the outset in a brand new span.

The CBF and other environmental groups are urging the Maryland Department of the Environment (MDE) to incorporate these kinds of practices into the state’s five-year stormwater permit, which is up for renewal.

At stake, they say, are the effects of runoff from the 15,000 lane miles of highways and 2,600 bridges overseen by the State Highway Administration.

Pollutants of concern from that runoff include oil, grease, gas, nutrients, heavy metals, PCB’s and PFAS, “so-called forever chemicals.”

At stake: runoff from the 15,000 lane miles of highways and 2,600 bridges overseen by the State Highway Administration.

Environmental scientists say stormwater, which carries nutrients and sediment as well as other harmful pollutants, is the fastest growing source of pollution in Chesapeake Bay.

The current draft MS-4 stormwater permit for the Maryland Department of Transportation (MDOT) continues to use outdated rainfall estimates to determine how robust the pollution controls along roadways and on bridges should be, Myers said.

It also relies too heavily on stream restoration projects to offset pollution, he and others argue. MDOT reported in 2023 that the impacts of nearly 5,000 acres of road surface were counterbalanced by stream restoration.

Hotter and More Polluted

The state has long been criticized for allowing jurisdictions, including Baltimore city and Baltimore County, to take stormwater mitigation credit for stream restoration projects.

Environmental watchdogs and community groups say these multi-million dollar projects are ineffective, while resulting in needless tree cutting and land-clearing.

“We’d like to get a commitment from the State Highway Administration to put in more green infrastructure, like infiltration, along the entire length of the highway – not just something that can be traded for the credits that are needed,” Myers said.

“Think of sensitive waterways like the Gunpowder River and the huge amount of I-95 that was recently reconstructed and widened in that area,” he continued.

Most of the mitigation and stream restoration credit for that highway work was done outside the Gunpowder watershed.

“It’s not really fair to the resource to be doing the impacts in one place and then getting the credits for it in some other place,” he said.

“We’d like to get a commitment from the State Highway Administration to put in more green infrastructure”  – Doug Myers, Chesapeake Bay Foundation.

The environmental groups want the permit to require a larger range of stormwater management strategies, including impervious surface removal, as well as green infrastructure.

Also to monitor for the presence of PCB’s and PFAS and to consider another environmental impact of roadway runoff: heat.

“With climate change, storms are getting stormier – more frequent and intense – and water is getting hotter, and it’s an issue for the Bay because warm water holds less oxygen than cooler water,” Myers said.

One way to mitigate that would be road surfaces required to be lighter in color to reflect rather than absorb heat.

“The state has never been required to address the heat that’s added by runoff,” Myers added. “If there’s no requirement to do so in the permit, the engineers are not going to do it.”

Stream Restoration

Critics have grown frustrated with MDE’s stormwater permitting policies under Governor Wes Moore, a Democrat, as well as his predecessor, Republican Larry Hogan.

In 2021, CBF and the Environmental Integrity Project sued MDE over permits issued to Baltimore county and city that they said are too lax and disproportionately impact low-income and Black neighborhoods downstream in the city.

In February, the Appellate Court of Maryland sided with MDE, finding that Maryland environmental officials have “wide flexibility” to choose permit terms they believe will achieve water quality standards.

The court held that MDE provided adequate evidence of the efficacy of stream restoration, street sweeping and other practices for which the jurisdictions take credit.

MDE had also argued that adequate supporting data for the impact of climate change “simply did not exist” when the permits were issued.

The critics continue to argue that the state and the courts are making the wrong call.

• Critics call one Baltimore stream restoration project “a debacle” as DPW pushes ahead with another (6/7/24)

“We’ve had most of our comments dismissed and we’ve exhausted the litigation approach,” Myers told The Brew.

They are now turning to “public pressure,” he added, noting that the public comment period on the draft permit ends this Thursday.