Stormwater Management Challenges in the Face of a Changing Climate

Originally published in the ASFPM May 2024 Insider

More frequent and intense rain events are overwhelming the nation’s aging infrastructure, including our stormwater management systems. A 2023 report from the RAND Corporation describes the challenges today’s extreme precipitation poses to stormwater management agencies and explores how to translate complex climate projections into actionable information for designing and implementing resilient stormwater management solutions.

For the report Turning Climate Information into Action for Stormwater Management in the Mid-Atlantic Region, authors Michelle E. Miro and Krista Romita Grocholski spoke with climate and stormwater professionals, engineers, and policy makers. Based on those interviews, they identified three main barriers to climate-informed stormwater planning and policy: (1) climate communication and uncertainty, (2) varying community priorities, and (3) infrastructure and regulatory constraints. The report then presents recommendations for how those barriers can be removed.

Bridging the gap between climate projections and practical solutions

Those who work to mitigate the effects of climate variability generally are not climate scientists, and the report dives into the difficulty in converting unprecedented data into practical solutions. In particular, engineers and stormwater managers are faced with the challenges of designing large-scale and costly projects while using one of many projected climate models. Which model to use presents its own consideration. What future economic conditions, emission, and policy scenarios are being referenced to generate the model? Which data points are collected and which are speculated? Professionals on the ground are required to digest and dissect these theoretical models, choose the best one, and hope that particular dataset isn’t invalidated before the project is completed. These decisions have a strong impact on cost, as well as getting necessary buy-in. Anyone who works in floodplain management knows the challenges of communicating technical data to (typically) laymen decision-makers, but throw in conceptual environmental projections and it can be a nightmare. The report relates that the stormwater professionals need independently produced guidelines on how to best select climate models and better educational materials to inform not only policymakers, but constituents and clients.

Critically, the report touches on the differences in what each community seeks to accomplish by the policy they’re implementing. All stakeholders must weigh the pros and cons of each proposed action, and some may be more well received than others. Overburdened communities are less likely to “experiment” with new rules when there is no guarantee of improvement. Those surveyed expressed a desire for more modern rules to be adopted by higher authorities, like state or federal government agencies, who have a greater capacity to troubleshoot any policy shortcomings. Additionally, stormwater professionals noted these policies should be supported by data and analysis, rather than speculation, and further spoke on how new flood maps could change the effective range of regulation. Those interviewed also noted that case studies are especially helpful when trying to overcome resistance in their communities as well as the need for independent organizations to provide commentary and research on the effectiveness of planning and the cost of inaction.

Infrastructure and its shortfalls have been a trending topic of debate in recent years and its effects on flood hazard mitigation are certainly a major concern. Large-scale aged infrastructure is not only falling into disrepair, but was designed for a climate we no longer have. These systems simply cannot handle the capacity of current rainfall trends, and some systems that were designed without environmental oversight can actually prove detrimental. Today, most stormwater control systems are produced with regulatory compliance in mind; that is, most systems adhere to the minimum standards. Managers expressed that there is no motivation to proceed beyond the compliance guidelines. The report notes, “One group gave an example in which attempts to work with other regional entities to respond to increasing storm sizes were dismissed because such increases were beyond regulatory requirements.” Stormwater professionals spoke about their concerns that there is little support from state or county leadership. Without the blessing of higher authorities, local leadership may be more reluctant to accept costly stormwater alterations.

What are the next steps for stormwater managers?

Climate change has already begun to wreak havoc on existing drainage infrastructure and render policies obsolete. Clearer, more approachable regulatory guidance is necessary to begin mitigating these problems. The report puts it best, “Stormwater entities need support in clarifying objectives, analyzing options, and illuminating trade-offs — all in the service of enabling a better understanding among constituents of the values at stake and facilitating better choices by decision makers.” The report also calls chiefly for independent research think-tanks to begin a deep survey into the types of data points professionals will find most useful, and to develop best-available tools and guidance in facing climate related challenges.

Specifically, the determination on how to select the best climate models is critical. Further, local engagement is paramount to better involve community stakeholders in the selection of stormwater solutions. Difficulties in educating policymakers require better materials that illustrate the benefits of better infrastructure and the high cost of doing nothing. Crucially, stormwater managers should have detailed and varied case studies to help better understand the lessons some communities have already learned when regulating and enforcing control methods.

The most important thing for all communities to understand is that adapting to extreme weather variability is not as easy as a succinct, technical implementation. Whatever policy is adopted, it is almost guaranteed that such regulation will need to be eventually altered to face an unpredictable climate. With this in mind, stormwater professionals, policymakers, and communities should work together to better understand what their particular region needs, and cooperate to ensure that it happens.