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Maryland Department of the Environment

MDE issues stormwater permits for large MD jurisdictions, advances climate resiliency and equity


Clean Water Act Municipal Separate Storm Sewer System (MS4) permits issued for Baltimore City, Anne Arundel, Baltimore and Montgomery counties; MDE releases plan to modernize stormwater regulations in the face of climate change

BALTIMORE (Nov. 5, 2021) – The Maryland Department of the Environment (MDE) has issued a series of municipal stormwater permits to advance Chesapeake Bay restoration while reducing flooding and making communities more resilient to the effects of climate change.

The municipal separate storm sewer system (MS4) permits were issued today for Baltimore City and Anne Arundel, Baltimore and Montgomery counties. The permits build upon and improve pollution prevention under prior permits and require local jurisdictions to not only keep pace but do more to help Maryland meet its Chesapeake Bay restoration plan requirements. The five-year permits are issued under the federal Clean Water Act.

Climate change results in more frequent and intense storms and more extreme flooding events that are impacting our communities. In response to these challenges, MDE has released a report, “Advancing Stormwater Resiliency in Maryland,” that provides a roadmap toward modernizing stormwater management in Maryland.

“Aggressive and achievable stormwater requirements for large Maryland jurisdictions are a critical part of our comprehensive, science-based plan for restoring the Chesapeake Bay,” said Maryland Environment Secretary Ben Grumbles. “MDE’s new municipal stormwater permits, along with our new climate action plan and innovative financing strategies for stormwater management, will help prevent stormwater pollution, reduce flooding and increase climate resiliency and equity to help ensure healthy watersheds and a green and growing Maryland economy.”

Maryland’s municipal stormwater permits

When it rains, stormwater washes excess nutrients, chemicals, and dirt from impervious surfaces, such as buildings, roads, and parking lots into local waters and the Chesapeake Bay. Excess stormwater runoff can also flood local communities, scour sediment from waterways, and degrade the health of stream systems.

MDE’s four permits continue the state’s robust work to reduce nutrient and sediment pollution from stormwater as part of a larger effort that requires all sectors, such as sewage treatment plants and septic systems, in Maryland and the surrounding region to protect and restore the Chesapeake Bay.

The MS4 permits are a result of extensive stakeholder engagement. The permits require local jurisdictions to maintain previous stormwater pollution reduction efforts. They also require additional stormwater pollution reduction, including restoring impervious surface areas that have little or no stormwater treatment with green infrastructure and other techniques. These new permits meet our Chesapeake Bay commitments and also increase accountability, enhance public education and include innovative and cost-effective monitoring options.

In the next five years the new permits add another 11,000 acres to the 35,000 impervious acres restored under prior permits. This restoration encourages climate resiliency and green infrastructure even as it continues to advance innovations such as pay-for-performance contracting, public-private partnerships, and new technologies. The permits also include new incentives for climate resiliency and green infrastructure projects.

Maryland’s 11 phase I urban jurisdictions have established themselves as national leaders in reducing stormwater pollution by collectively investing $745 million in clean water infrastructure. Since July 2019, MDE’s Water Quality Finance Administration has guaranteed $117.8 million in low interest loans to counties and local governments for stormwater restoration projects, and another $218.6 million in low interest loans are pending for planned projects. During the prior MS4 permit term, which started in 2014, the Chesapeake Bay Trust awarded an additional $36.5 million in grants to stormwater programs for restoration projects, which leveraged another $27.7 million in matching funds. Maryland continues to push for additional federal funding for local stormwater projects – especially for those that increase climate resiliency in underserved communities and for those that help sustain our Chesapeake Bay restoration efforts for decades to come.

Modernizing stormwater management for climate change

Advancing Stormwater Resiliency in Maryland” finds an increasing number of extreme rainfall events will lead to more urban and riverine flooding in Maryland unless steps are taken to mitigate their impacts. The University of Maryland’s Center for Disaster Resilience has characterized urban flooding as a “significant source of economic loss, social disruption, and housing inequality.”

In 2022, MDE will engage in citizen and stakeholder meetings to build on the strengths of Maryland’s environmental non-profits, academic, development, building and local government sectors to find ways to protect the built environment starting with the most vulnerable underserved and underrepresented communities. By incorporating the most recent precipitation estimates, MDE expects to encourage innovative thinking about managing a future with higher risks.The report was prepared in response to legislation that updated Maryland’s stormwater management law. That law, which became effective June 1, requires MDE to report on the most recent precipitation data available, investigate flooding events since 2000, and update Maryland’s stormwater quantity management standards for flood control.

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