Flooding is a serious and growing concern in Montgomery County. Flooding can damage property, disrupt transportation, harm ecosystems, and create safety concerns for residents. While flooding cannot be eliminated entirely, multiple county agencies have a role in mitigating the impacts of flooding. As storms become more intense and frequent due to climate change, Montgomery Planning recognizes the urgency of reducing vulnerabilities in both existing communities and future development.
Why flooding happens
Flooding occurs when rainfall overwhelms the ability of soil to infiltrate water and the capacity of natural and built drainage systems such as streams, wetlands and storm drains. In Montgomery County, older development patterns and aging infrastructure often compound these natural risks.
Our approach
Montgomery Planning is responsible for master planning, development review and policies related to land use. Master planning and smart growth are among many important tools in mitigating the risks of flooding in the county.
Montgomery Planning recognizes the imminent need to maintain growth and development while improving the county’s environmental resilience. Important to realizing these goals is Montgomery Planning’s support of the county’s ongoing interagency process of identifying flood hazard areas and developing policies, strategies, infrastructure improvements, and management approaches to reduce flood risk. Some of these strategies can include land use planning and development review strategies aimed at:
- Designing for resilience: encouraging site designs that are more environmentally context sensitive.
- Protecting natural systems: preserving and restoring forests, floodplains, and wetlands that naturally absorb and reduce floodwaters.
- Planning for resilience by recommending cutting edge environmental solutions in Master Plans for implementation on individual sites.
- Supporting the county’s updates to stormwater management policies, codes, regulations, and infrastructure that better handle today’s storm events and prepare for tomorrow.
- Increased agency coordination: working together with other county agencies, like the Department of Permitting Services (DPS) and the Department of Environmental Protection (DEP), can lead to solutions and new policies, strategies, and management approaches to reduce flood risks in the county.
The role of new development
Well-planned new development can help mitigate flooding, not only through improving and upgrading pre-existing storm drain infrastructure, but by the application of new and stricter standards. Modern requirements and best management practices for environmental protection, and site design are far stronger than those applied to older neighborhoods. By incorporating green infrastructure, permeable surfaces, and stronger environmental protections, new projects can reduce runoff and provide long-term resilience benefits.
Looking ahead
Flooding will remain a challenge, but Montgomery County can reduce risks and create safer communities by making resilience a core part of how we grow. Through careful master planning, stronger development standards, and ongoing community collaboration, we are committed to ensuring that future generations inherit a county better prepared for the realities of a changing climate.
Frequently asked questions
Compared with undeveloped land, development can contribute to flooding by increasing impervious surfaces. On the other hand, the kinds of rainfall events that are now causing most of the urban flooding problems are so intense that they frequently overwhelm the ability of any land surface, pervious or impervious to infiltrate water and reduce runoff. The county is currently mostly built out with little amount of vacant land left for new development. Therefore, most of the future growth will be through redevelopment of already developed properties, which is expected to generate relatively small net increases in impervious surfaces in the future. There is overwhelming evidence that greater flooding risks in the future will be caused more by bigger rainfalls than the relatively small increase in impervious surfaces due to development. Developing sensibly in the future, especially through smart growth and redevelopment which improves stormwater management over existing conditions, will continue to be important, but the greater challenge is to find ways to reduce the flooding hazards that are already occurring and are expected to worsen with continued climate change.
While stormwater management and flood mitigation are closely related and overlap, they serve distinct purposes in protecting communities from water-related issues.
In Montgomery County, stormwater management is designed to protect the quality of stormwater entering our streams. It seeks to control the quantity and quality from rainfall events of certain intensities and durations, as specified by regulations. It uses techniques such as erosion control, vegetative buffers, detention and infiltration practices, inlets, and conveyance structures to reduce flooding, manage soil erosion and sedimentation, protect natural habitats, and improve stormwater quality entering streams.
Flood mitigation seeks to reduce the likelihood and severity of damage caused by extreme rainfalls. It uses stormwater management improvements such as conveyance and storage infrastructure, as well as non-structural measures such as public notifications before and during severe weather events, improving drainage, floodproofing critical structures, and creating more stringent stormwater management design standards, regulations, and building codes to protect lives, property, and infrastructure from flood hazards.
Stormwater management is a set of tools and practices that can contribute to broader flood mitigation efforts. Effective stormwater management can reduce the overall risk of flooding by managing runoff more efficiently, making it a crucial part of protecting communities from extreme weather.
Montgomery County’s central flooding website directs residents to information about what to do before and during floods and provides an overview of the comprehensive flood management planning process. This will also be the home for all future information related to flooding, including the public flood viewer tool, and it will be modified and enhanced as the Department of Environmental Protection’s Comprehensive Flood Management Plan (CFMP) process continues.
Montgomery Planning is one of seven core interagency stakeholders in the Department of Environmental Protection’s CFMP process. Montgomery Planning is providing technical assistance including GIS mapping layer files and expertise related to master planning, zoning, development review and design. Our agency’s expertise is critical to lending guidance, data, and decision-making for the creation of the CFMP. Looking ahead, we’re excited to contribute to the county’s efforts to address future flood risks in the county.