Sun over Baltimore by Joanne C Sullivan licensed under Creative Commons.

As Baltimore seeks to eliminate vacant housing by 2040 — and build vibrant, prosperous, and sustainable communities — the city’s leaders, developers, and residents should incorporate “blue-green” corridors into residential and commercial development.

This natural infrastructure, which combines greenery and waterways, would strengthen the city’s resilience to environmental and climate risks and enrich communities as they rebuild and revitalize themselves.

Vacancy in Baltimore

Like many post-industrial American cities, Baltimore’s vacancy rate has increased as its population has declined. Abandoned and neglected properties are a burden to their neighborhoods and to the city as a whole, decreasing the value of nearby inhabited homes, shrinking the tax base, and eroding social cohesion.

Baltimore has been making steady progress in addressing this issue, reducing vacant properties by more than 20% between 2020 and 2025. While this is impressive, Mayor Brandon Scott has argued for the need to scale up redevelopment efforts further, mobilizing additional resources and moving more quickly to revitalize neighborhoods.

Reframe Baltimore, a $3 billion, 15-year initiative announced in 2023, aims to meet that need by redeveloping all remaining vacant properties in the city, issuing grants to support homeownership and prevent displacement, and improving the infrastructure that serves neighborhoods affected by high vacancy rates.

Filling empty houses is crucial for economic development and the creation of safe communities. As the city works with the state, private developers, nonprofits, and other stakeholders to implement the project, there is also an opportunity to further transform neglected neighborhoods into thriving, sustainable places to live.

Why build blue-green corridors?

Image by the author.

Blue-green corridors are networks of linear parks integrated into neighborhoods that combine green space, such as parks and forest patches, with waterways and/or stormwater infrastructure, such as streams, wetlands, bioswales, and retention ponds.

Blue-green corridors offer an approach that aligns with Baltimore’s housing and revitalization goals. Unlike large parks or forests, they wouldn’t require significant housing to be cleared. Compared with isolated pocket parks or gardens in vacant lots, they would better mitigate climate threats and offer more substantial environmental benefits for a broader share of the community.

These benefits include:

***Flood prevention: ***Paved surfaces and buildings tend to increase the risk of flooding in urban areas, rapidly channeling rainwater into available pathways and waterways like streams, sewers, and streets. Flooding is a real threat in Baltimore: A 2018 storm produced floods as high as 7 feet in one area of West Baltimore.

Vegetated landscapes, such as forests, gardens, or wetlands, absorb stormwater and reduce the intensity of urban flooding. Interspersing new housing with blue-green corridors would reduce the risk of harm to homes and residents from extreme storms.

Better water quality: Impervious surfaces also exacerbate eutrophication, or excessive amounts of nitrogen and phosphorus dumped into waterways. The consequences of nutrient-loading were seen this fall when an intense “pistachio tide” — a bloom of sulfur bacteria — killed thousands of fish and filled Baltimore’s Inner Harbor with a noxious smell for weeks.

Blue-green corridors would intercept and absorb nutrients in runoff and reduce the fuel that powers bacterial blooms in the Chesapeake Bay. Reducing nitrogen and phosphorus in the Bay improves water quality for people, fisheries, and ecosystems as a whole.

Mitigating extreme heat: This summer, Maryland saw an increase in heat-related deaths, and Baltimore City was the jurisdiction with the highest number in the state. The concentration of tall buildings and materials create what’s called the urban heat island effect, raising temperatures even higher than they would be otherwise.

Green spaces, especially those with tree cover, provide an important cooling effect. Blue-green corridors lined with tall trees would help lower temperatures in newly redeveloped areas and make them safer and more comfortable for residents.

Other benefits: Trails connecting different parts of the city provide space for hiking, running, and other recreation. Parks and other green spaces are also desirable amenities that improve nearby property values, which is especially meaningful for these long-neglected neighborhoods.

Mission match

The city has already started working on natural corridors through its Baltimore Green Network plan, which aims to turn vacant properties into green spaces that connect to community hubs such as schools and commercial centers. Parks like Stony Run Trail are examples of how to integrate vegetation and waterways across neighborhoods.

Blue-green corridors have their own costs in terms of construction and maintenance, and reduce space for new houses. But with these corridors, the homes built by Reframe Baltimore would be safer, healthier, and more financially secure in the face of evolving climate, economic, and social conditions. Baltimore City has adopted the “triple bottom line” approach — people, prosperity, and environmental sustainability — for its key initiatives, and integrating blue-green corridors into Reframe Baltimore would help achieve that mission.