Our Impact and Results

In mid-June 2025 a cloudburst dumped up to 4 inches of rain in 30 minutes over the West Virginia panhandle. Five people died and extensive damage to roads, bridges, and natural gas lines was reported.

At the time, an emergency management official said the damage was so extensive that first responders had trouble reaching some areas.

The cloudburst came just days after downpours in San Antonio, Texas, dropped more than 7 inches of rain over several hours. Floodwaters there carried more than a dozen cars into a creek and 13 people were killed.

A warming planet results in an increased frequency and severity of heavy rain events like these.

In the words of the West Virginia emergency management official, “It happened so quickly and so fast. … I’ve been doing this for 35 years. I’ve seen major floods … in the city and the county. I’ve never seen anything like this.”

Climate models show that the air can hold as much as 7 percent more moisture for every 1°C of warming. This means that, on average, not only is the air warmer than it was before about 1970, it also is moister. In turn, these conditions likely have led to a 5 to 10 percent increase in the severity of heavy rain events.

Indeed, the U.S. Global Change Research Program confirmed in a 2023 report that intense, single-day precipitation events have been on the rise for the last few decades.

A rising economic toll

Severe rain events carry an increasingly large economic toll as homes and businesses are flooded. The Federal Emergency Management Agency (FEMA) ranks flooding as both the most common and the costliest type of disaster in the United States. FEMA reported that between 1980 and 2000, its National Flood Insurance Program paid out $9.4 billion in insurance claims. That payout rose to more than $62 billion over the following 20-year period, a greater than six-fold increase.

Downpours don’t occur everywhere and can be hard to predict. But when they do strike, the effects of climate change mean they are more likely to result in a flash flood that can overwhelm existing stormwater infrastructure and challenge the capacities of even new and recently upgraded systems.

Grading stormwater infrastructure

The American Society of Civil Engineers. (ASCE) 2025 Report Card for America’s Infrastructure highlights the challenge. ASCE assigned a grade of “D” to the nation’s stormwater infrastructure, the same grade it assigned in 2021 as part of its previous assessment.

The recently released 2025 Report Card noted that although no comprehensive national database of stormwater infrastructure exists, one estimate suggests there are 3.5 million miles of storm sewers, 270 million storm drains, and 2.5 million stormwater treatment assets across the country. The construction of new homes, businesses, and factories means that the amount of land area covered by impervious, paved surfaces expands by around 1% every five years.

The U.S. Environmental Protection Agency estimated that the 20-year price tag for large stormwater system improvement projects had risen from $23.8 billion in 2012 to $115.3 billion a decade later.

To address that need, Congress passed the Infrastructure Investment and Jobs Act in 2021 and the Inflation Reduction Act in 2022. Together, these laws called for $46 billion in new federal funding for the stormwater, wastewater, and drinking water sectors through 2026.

Gray and green infrastructure

Stormwater management investments targeted by the bills include piped systems, detention basins, ditches, canals, channels, and roadway conveyance systems.

In addition, green stormwater infrastructure increasingly is being incorporated into new developments, and retrofitted alongside older systems. Green engineering designs also can be coupled with traditional infrastructure to maximize the benefits from vegetation, soils, site grading, and natural filtration processes.

Other types of green infrastructure (for example, rain gardens, constructed wetlands, vegetative buffers, roadway bioswales, and permeable pavements, among others) help reduce runoff and minimize erosion, contributing to water quality improvements in streams, rivers, and lakes.

The ASCE Report Card said that while these types of green infrastructure projects are valuable in addressing drainage and water quality, they typically cannot provide enough capacity on their own to manage large-scale stormwater events like those in West Virginia and Texas.

Instead, stormwater infrastructure resiliency may best be achieved through a mix of green, gray, and natural infrastructure; land-use planning to guide urban growth; updated asset management and emergency action plans; and, in water-scarce parts of the country, the productive reuse of stormwater.

One town’s stormwater challenge

The ASCE recommendations offer useful guidance for officials in small cities and towns grappling with the effects of increasingly severe rain events.

For example, in Hope, Arkansas, in the southwest part of the state, stormwater drainage issues are impacting a 60-year-old park. During heavy rainfall events a walkway and parking lot next to a new preschool play structure become swampy, and the grass around a stand of trees in the 23-acre Northside Park is unusable.

Parks play a vital role in community resilience, not only offering opportunities for recreation and relaxation, but also providing a place for stormwater to flow during extreme weather events, helping protect nearby homes and businesses from dangerous floodwaters.

Elected officials in Hope believe that a stormwater management approach that blends natural features with green stormwater infrastructure could better handle stormwater runoff and help Northside Park regain its full potential.

In September 2024, the city approved plans to improve the park, including installation of a splash pad and other recreational facilities. Those improvements cannot be completed, however, without a stormwater drainage solution.

The community sought engineering services from EWB-USA’s Community Engineering Corps (CECorps) program services. Founded in 2014, CECorps leverages an extensive volunteer network to provide pro-bono engineering and consulting services in partnership with communities throughout the U.S., its Territories, and Tribal Entities to address infrastructure issues and inequities.

Santa Clara University’s Engineers Without Borders Chapter took on the project and was assigned to help with the drainage analysis and planning. The team is supported by a licensed professional engineer in Arkansas who offers knowledge of regional flooding challenges.

The project’s scope of work includes a detailed evaluation of the sources of the flooding and possible solutions, which may include more efficient park drainage systems and possible reuse/stormwater treatment systems such as rain gardens or biofiltration planting.

The preliminary engineering report outlining potential drainage solutions for Northside Park is set to be completed by CE Corps by the end of 2025.

The stormwater challenge facing Hope, Arkansas, is a complex one, made more challenging by the knowledge that a warmer climate can spawn intense, often unpredictable downpours that can be costly in terms of property damage and loss of life.

The EWB-USA team did a good job working with the community and incorporating their suggestions.

[The project] brought the community together. We have been able to support and work with other communities. [We] used to carry big jugs of water [and] couldn’t bath in houses before, now we can.

The students can study in a formal place, kids feel safer and happier and teachers are more stimulated. They used to have a dirt floor and there was lots of dust so are happy to now to have a building with a floor.