Introduction
Montpelier, the capital of Vermont and the smallest U.S. capital by population with approximately 8,000 residents, is located in Washington County at the confluence of the Winooski River and its tributaries, the North Branch and Stevens Branch (City of Montpelier, “Welcome to Montpelier”; Figure 1). Montpelier’s river-centered valley and location within the FEMA-designated 100-year floodplain make it highly vulnerable to flooding, especially during heavy rainfall or spring snowmelt (City of Montpelier, Flood Guide; First Street Foundation). While its residents value the city’s proximity to water, and the city has consistently provided high-quality water services, the growing threat of flooding poses significant challenges. Today, Montpelier’s key water management priorities include mitigating flood risks, safeguarding critical infrastructure, and maintaining public trust.
History of Flooding
In July 2023, Montpelier experienced a catastrophic flood that resulted in an estimated “$1 billion in response, recovery, and social support costs” within the state (Office of Governor Phil Scott). During this flood event, the city recorded its highest-ever rainfall, measuring 5.28 inches at the airport (US Department of Commerce, 2023). The Winooski River peaked at 21.29 feet, which inundated areas around downtown Montpelier with several feet of water (City of Montpelier, n.d.). The heavy rainfall disrupted services, Green Moutain Power reported outages, and the storm inundated various roads throughout the city (Petenko & Thys, 2023). As Montpelier faces increasing flood risks, the city’s ability to maintain resilient water management systems that ensure infrastructure protection and safe water provision has become more critical than ever.
(Burlington Free Press)
However, the flood event of 2023 was not the first time that Vermont’s capital faced flooding. In fact, Montpelier has endured several flood events, with four of the most severe floods happening in the last century: 1927, 1936, 1992, and 2023 (City of Montpelier, n.d). Both the 1927 and 2023 floods have been classified as 100-year-recurrence events (NOAA, “25th Anniversary Montpelier Ice Jam”; US Geological Survey). Yet, once considered 1-in-100-year storms in Washington County, these floods are “now likely to occur about every 63 years” due to climate change (Muyskens et al.). Considering the impacts of climate change, Montpelier will likely face a greater frequency of flooding at a greater magnitude, and the city’s downtown area will likely flood again (Mahan).
Flooding Exacerbated By Climate Change
Two main factors driving flooding in Vermont are the increases in average annual precipitation and temperature. Since the 1800s, rainfall has steadily increased by 0.67 inches per decade, with the rate accelerating to “nearly an inch per decade by the late 1960s” (Mahan). Vermont now experiences “2.4 more days of heavy precipitation than in the 1960s” (Clark, M., et al., 2021). However, it is not just the increased rainfall but its timing and duration that have caused flooding. A NOAA analysis of the July 2023 floods found that most rain in Vermont fell within a “6 to 9 hour time frame,” with higher rates over shorter periods significantly increasing the potential for flash flooding (NOAA’s National Weather Service). Additionally, rising temperatures have worsened flooding risk. Over the past 50 years, Vermont’s winter air temperatures “have increased by more than 4°F,” and summer temperatures by over 2°F (Vermont Department of Health). This warming has allowed the atmosphere to hold more moisture, leading to heavier downpours and increased flooding risk (Mahan).
Scope Of Research
Our research aims to provide a comprehensive approach to flood mitigation in Montpelier, Vermont, by addressing upstream and downstream flooding interventions.
- Floodplain Challenges and Limitations
Given Montpelier’s location at the foothills of the Green Mountains, relocating residents and infrastructure entirely out of floodplains would be the most effective long-term solution to flood risks. However, this approach may not be feasible in Vermont due to high costs and the prevalence of flooding across the state. Instead, our research focuses on scalable interventions that can adapt to Montpelier’s unique urban context.
- Prioritization of Flooding Over Water Supply Issues
Given that Montpelier and a few surrounding towns rely solely on Berlin Pond for their drinking water needs, we acknowledge that this water supply is vulnerable. However, our research prioritizes the urgent and recurring issue of flooding, particularly given the catastrophic events of 2023 and 2024. By addressing flooding as the most pressing concern, we aim to highlight resilient infrastructure that can also have secondary benefits for water quality.
- Downstream Interventions: Green Stormwater Infrastructure (GSI)
The core of our proposed solutions lies in implementing green stormwater infrastructure (GSI) as a downstream intervention. GSI is particularly effective for managing smaller storms and mitigating the impacts of day-to-day flooding by:
- Diverting water from rivers reduces flood burdens (Atkins; Sun, et al),
- Improving water quality through natural filtration processes (Atkins; Sun, et al), and
- Supporting urban resilience by creating “sponge city” systems that manage water on-site (Sun, et al).
- Urban and Economic Co-Benefits
Beyond flood mitigation, GSI interventions can foster a more sustainable urban environment by:
- Reducing combined sewer overflows (CSOs) (Kwak),
- Creating green spaces that enhance urban livability (Gies), and
- Attracting people and businesses, thus contributing to local economic growth (Gies).
Philosophy of Adaptation
These strategies emphasize resilience by helping communities adapt to and coexist with water rather than solely defending against it. Moreover, they enhance urban livability by creating green spaces and recreational opportunities, making the city more attractive and sustainable. Together, these interventions demonstrate the potential for Montpelier to not only manage everyday flood risks but also thrive as a greener, healthier, and more resilient capital.
Downtown Flooding
Much of downtown Montpelier lies within the Winooski River floodplain and was heavily impacted during the July 2023 flood (Figure 4). Montpelier’s vulnerability to riverine flooding is rooted in the city’s historical settlement patterns, which centered development along the river’s edge and its steep topography. The downtown sits on flat, low-lying land near the river, surrounded by steep hills (Figure 5). During heavy rain events, runoff from these slopes quickly drains into the downtown, increasing the risk of flash floods, washouts, and water contamination (Southern Tier Central Region Planning & Development Board). Flooding in this area poses significant challenges to Montpelier’s economy and community. While preventing all flooding is unlikely, the following recommendations propose ways to mitigate its effects and build long-term resilience.
Short-Term Solutions
Intervention #1: Relocate essential infrastructure out of the floodplain and implement floodproofing measures for critical facilities that cannot be moved
As previously mentioned, the catastrophic July 2023 flood disrupted services in Montpelier, with essential services cut off. Figure 6 shows that critical infrastructure like electrical substations and water treatment facilities are in the floodplain. To avoid vital service disruptions in future storms, it is necessary to take pre-emptive measures to relocate and fortify essential services. We recommend that Montpelier strategically relocate essential infrastructure out of the floodplain and implement floodproofing measures for critical facilities that cannot be moved.
To execute this approach, the city should administer a phased approach to reduce the vulnerability of critical infrastructure to flooding. First, electrical substations in the floodplain would be relocated to higher ground outside of high-risk areas. This process would require identifying suitable sites that meet technical and logistical requirements, ensuring minimal disruption to the city’s power supply during the transition. Comprehensive floodproofing measures would be implemented for critical facilities, such as the Montpelier wastewater treatment facility located along the Dog River Branch of the Winooski River, that cannot be relocated. Interventions might include installing watertight barriers, upgrading drainage systems, lifting crucial machines above ground, and reinforcing building foundations to withstand floodwaters. This dual strategy would protect essential services during flood events and reduce the financial burden of future flood damage.
Intervention #2: Slowdown runoff that will contribute to flooding downtown using Green Stormwater Infrastructure (i.e. rain barrels, bioswales, terraced rain gardens, and retention basins)
To mitigate downtown flooding, Montpelier should implement Green Stormwater Infrastructure (GSI) to slow and manage runoff before it reaches the city’s low-lying areas. This would involve strategically placing rain barrels near homes and businesses to capture and store water that runs off roofs, reducing building runoff during heavy rain events. Bioswales and terraced rain gardens can be installed along streets, parking lots, and community spaces to intercept and absorb water, promoting natural infiltration and reducing the volume of water flowing downhill. Retention basins, designed to hold excess runoff temporarily, could also be constructed in upstream locations to delay the flow of water into the downtown area. These GSI measures would reduce flood pressures on the city’s drainage system and provide additional benefits, such as improved water quality, enhanced green spaces, and urban cooling. Public outreach and incentives for property owners to adopt GSI on private land should complement these efforts to foster a community-wide approach to flood resilience. However, it is necessary to acknowledge that GSIs can only reduce runoff to a certain extent and will not prevent the city from flooding during a large storm. To have effective flood management for large rain events, we need to consider broader and more long-term solutions to flood management.
Medium- and Long-Term Solutions
Intervention #3: Regional approach to floodplain and watershed management
A regional approach to floodplain and watershed management within the Winooski Watershed is essential to effectively mitigate downstream flooding during major storm events. Large-scale interventions upstream can significantly reduce the volume and velocity of water flowing into Montpelier’s flood-prone downtown. Efforts such as those led by the Friends of the Winooski River, a non-profit organization dedicated to restoring and protecting the watershed, demonstrate the importance of preserving natural floodplains, wetlands, and riparian buffers to absorb and slow runoff (Winooski River Basin Program). Similarly, the Central Vermont Regional Planning Commission (CVRPC) has developed the Upper Winooski River Corridor Management Plan, which provides actionable river corridor restoration and protection strategies (Central Vermont Regional Planning Commission).
Other regional efforts like reforestation and soil stabilization in upstream areas, coupled with stormwater management initiatives outlined in the Vermont Department of Environmental Conservation’s Winooski River Basin 8 Tactical Basin Plan, are key to reducing erosion and enhancing water retention (Vermont Department of Environmental Conservation). For a regional approach to be successful, coordination among municipalities, landowners, and watershed organizations is critical to implementing these measures. This will ensure that flood management efforts are consistent and comprehensive. By addressing flooding at its source, this regional approach not only protects Montpelier but also benefits the entire watershed, providing ecosystem services like improved water quality, biodiversity, and climate resilience. Collaborative planning and funding mechanisms must align local and regional priorities and turn this vision into actionable outcomes.
Intervention #4: Flood preparedness workshops for residents
Lastly, flood preparedness workshops can provide residents with essential knowledge and practical tools to better understand flood risks, prepare for potential flooding events, and protect their homes, families, and communities. These workshops could feature presentations, hands-on demonstrations, and expert panels, all tailored to community needs. Hosting them in accessible locations like community centers or schools—and potentially offering virtual options—will maximize participation. Scheduling workshops before peak flood seasons will allow residents time to implement preparedness measures, and repeating them throughout the year ensures continuous awareness. It also needs to be noted that there is no single correct way to structure or organize these workshops, but the key is to ensure that they provide essential support to those who need it most.
Montpelier already offers valuable online resources such as its Flood Guide, Flood & Disaster Recovery Assistance webpage, and How To Stay Safe in a Flood webpage, among many others (City of Montpelier, Flood Guide; City of Montpelier, Flood and Disaster Recovery Assistance; Vermont Department of Health). Recurring workshops can complement these online resources by raising awareness, fostering community connections, and better preparing residents to respond to future floods. By equipping residents with the right knowledge and resources, these workshops can help them adapt to the Winooski River’s presence, allowing them to live with it rather than constantly fighting against it.
Conclusion
Flooding continues to be a significant challenge for Montpelier and the broader Central Vermont region, and with the impacts of climate change, the threat of more frequent and severe floods is on the rise. As a result, cities like Montpelier need to take proactive measures immediately. While the proposed interventions may not eliminate the possibility of extreme flood events, they focus on redirecting and storing water away from vulnerable areas, easing the pressure on existing infrastructure. Relocating critical infrastructure to higher ground, raising public awareness, and fostering regional collaboration will strengthen Montpelier’s resilience to flooding. By taking strategic action today, the city can better manage future risks and protect its communities from the growing impacts of climate change.
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