In the spring of 2012, the city of South Bend, Indiana had a problem that cost its residents a billion gallons of raw sewage a year. Every time it rained hard, the city's combined sewer system — pipes that carry both sewage and stormwater in a single network, a design inherited from the 19th century — would overwhelm. The excess would pour, untreated, into the St. Joseph River. The federal consent decree hanging over the city demanded a fix. The estimated price tag: more than $800 million in new tunnels and pipes.
South Bend didn't build those tunnels. Instead, the city installed 165 sensor-equipped monitoring sites and 13 automated gates and valves across its existing sewer network. The system, developed by researchers at the University of Notre Dame and deployed by Xylem, reads water levels in real time and redirects flow from overtaxed trunk lines to under-utilized parts of the network — essentially teaching the city's century-old pipes to think.
The results were staggering. Dry weather overflows were eliminated entirely. Combined sewer overflow volumes dropped by more than 80 percent — roughly one billion gallons per year kept out of the river. E. coli concentrations in the St. Joseph River fell by more than 50 percent. And the city saved approximately $400 million in capital expenditure by optimizing what it already had, rather than digging new infrastructure. Annual operating and maintenance costs dropped by $1.5 million.
"We spent 400 million dollars less than originally estimated, achieving the greater environmental benefit and level of service, just by optimizing the existing system in the ground," said Eric Horvath, South Bend's Director of Public Works. In 2021, the Department of Justice and the EPA endorsed the city's revised long-term control plan, formally recognizing that smart technology had delivered environmental gains 10 to 15 years ahead of schedule.
The D-Grade Problem
South Bend's story is remarkable — and desperately needed everywhere. In November 2025, the American Society of Civil Engineers released its 2025 Infrastructure Report Card and gave stormwater systems a grade of D, tied with transit for the lowest mark among all 18 infrastructure categories assessed. It was the same failing grade stormwater received in 2021, the first time ASCE included the category.
The numbers behind that grade are sobering. More than 60 percent of the nation's stormwater utilities report that aging infrastructure poses a significant concern for their long-term needs. Forty-two percent say they simply don't have the funding to cover their capital needs. The length of impaired rivers and streams in the United States has grown from roughly 424,000 miles in 2010 to more than 703,000 miles by 2022. The EPA's 2022 Clean Watershed Needs Survey estimated that the 20-year need for large stormwater systems had ballooned from $23.8 billion in 2012 to $115.3 billion a decade later — nearly a five-fold increase.
Across all water infrastructure categories, ASCE identified a combined stormwater and wastewater funding gap of $690 billion. The 2021 Infrastructure Investment and Jobs Act and the 2022 Inflation Reduction Act injected $46 billion in new funding for stormwater, wastewater, and drinking water — meaningful, but nowhere near enough to close the gap. And with that IIJA funding approaching its September 2026 sunset, the question of what comes next is urgent.
The Green Revolution That's Already Working
Philadelphia offers perhaps the nation's most ambitious answer to the stormwater crisis — and the most thoroughly documented proof that green infrastructure works at scale.
In 2011, the Philadelphia Water Department launched Green City, Clean Waters, a 25-year plan to manage stormwater through green infrastructure rather than relying solely on traditional gray systems — massive tunnels and storage tanks. Fifteen years in, the results speak for themselves. The city has completed more than 1,100 green stormwater infrastructure projects, achieving over 3,850 "greened acres" — parcels where rain gardens, permeable pavement, tree trenches, and bioswales capture stormwater before it ever enters the sewer system.
The cumulative impact: nearly four billion gallons of stormwater and sewer overflow kept out of local waterways each year. The program has exceeded every major regulatory milestone ahead of schedule, surpassing its Year 15 Greened Acre target required under the city's consent order with the Pennsylvania Department of Environmental Protection. Along the way, it has transformed neighborhoods — turning parking lots into parks, barren streetscapes into tree-lined corridors, and abandoned lots into functioning wetlands.
The program hasn't been without growing pains. Costs have ballooned to roughly $4.5 billion at the halfway mark, and during excavation on the Frankford Creek Crossing Improvement Project, crews encountered unexpected soil contamination that required enhanced environmental monitoring. These are the real complexities of building green infrastructure in post-industrial cities. But the core premise — that nature-based systems can manage massive volumes of stormwater at urban scale — has been validated beyond any reasonable doubt.
When Pipes Learn to Think
The next frontier isn't just green versus gray — it's making all stormwater infrastructure intelligent.
In July 2026, Opti (formerly OptiRTC) announced a partnership with Oldcastle Infrastructure to create what they call "America's first fully integrated, digital-by-default stormwater storage system." Called SmartCapture, the technology embeds continuous monitoring and adaptive control directly into precast concrete storage modules during manufacturing. The system evaluates weather forecasts and real-time water levels to proactively manage stormwater capture, storage, and release — no external control infrastructure required.
"Opti was built on the belief that actively managing stormwater upstream is the key to relieving capacity constraints while keeping growing capital and maintenance costs in check," said Alex Bedig, Opti's Chief Innovation Officer and Co-Founder. The shift, Bedig noted, is "from presumed to observed performance" — meaning stormwater systems that prove they're working, in real time, rather than relying on design assumptions.
Meanwhile, cities across the country are deploying AI and geographic information systems to target where green infrastructure will deliver the greatest impact. Chicago is using AI-driven GIS mapping to identify optimal locations for green roofs, rain gardens, and permeable surfaces based on flood risk, runoff patterns, and neighborhood need. In California, the software company 2NDNATURE uses video and imagery to monitor storm drains in real time, detecting blockages and debris before they cause flooding — replacing reactive emergency response with predictive, data-driven maintenance.
The EPA has also recognized the shift. In October 2025, the agency updated its guidance on off-site stormwater management, clarifying when municipalities and developers may use regional or off-parcel facilities to meet stormwater permit requirements. The updated guidance makes it easier for communities to build green infrastructure at scale — aggregating stormwater controls across larger areas rather than requiring every individual parcel to manage its own runoff. It's a regulatory shift that could unlock economies of scale for bioswales, regional detention, and constructed wetlands.
Washington's $3 Billion Bet — And What Comes Next
Not every city can avoid tunnels. Washington, D.C.'s Clean Rivers Project is building nearly 18 miles of deep-bore tunnels — some more than 100 feet underground and 23 feet in diameter — to capture combined sewer overflows before they reach the Anacostia and Potomac Rivers. The $3 billion project, mandated by a 2005 federal consent decree, aims for 96 percent system-wide CSO reduction.
But even DC has recognized that gray infrastructure alone isn't enough. A 2015 modification to the consent decree incorporated green infrastructure requirements — rain gardens, permeable pavement, and urban tree canopy — to complement the tunnels. The final phase, the $819 million Potomac River Tunnel, received its design-build contract in late 2023.
The lesson from Washington isn't that tunnels are obsolete — it's that the smartest cities are building hybrid systems. Gray infrastructure for the heaviest loads. Green infrastructure to reduce the volume that reaches the gray system. And smart technology to optimize everything in between. The cities that combine all three are seeing results that neither approach could deliver alone.
The Funding Cliff and the Southeast Opportunity
The financial picture is both promising and precarious. In April 2026, the EPA announced $80 million in grants under the Sewer Overflow and Stormwater Reuse Municipal Grant Program, with at least 20 percent of allocations required to go toward low-impact development and green infrastructure. New York State committed $61 million for eight stormwater resilience projects through its Green Resiliency Grant program. FEMA has approved more than $117 million for flood mitigation projects in Texas and Louisiana alone, with another $250 million spread across 20 states under the Building Resilient Infrastructure and Communities (BRIC) program.
But the IIJA money — the largest single infusion of water infrastructure funding in a generation — hits its spending deadline in September 2026. What comes after is uncertain. The stormwater management market is projected to nearly double from $8.25 billion in 2025 to $15 billion by 2033, but that growth depends on sustained public investment meeting private innovation halfway.
In the Southeast, the opportunity is acute. Atlanta is building "sponge parks" and underground stormwater vaults in neighborhoods that have endured decades of chronic flooding, part of a broader green infrastructure strategy developed in coordination with the Georgia Stormwater Management Manual. Across the region, rapid development is paving over land that once absorbed rainfall, while intensifying storms are delivering more water in shorter bursts — exactly the combination that overwhelms traditional stormwater systems.
What Smart Stormwater Actually Looks Like
The common thread across all of these efforts — South Bend's smart sewers, Philadelphia's green acres, Opti's digital-by-default modules, Chicago's AI-targeted installations — is a fundamental shift in how we think about stormwater infrastructure.
The old model was static: pour concrete, lay pipe, hope it's big enough for the next 50 years. The new model is adaptive: embed sensors in the system, connect them to weather forecasts and flow models, let the infrastructure respond to conditions in real time, and use nature where nature works better than concrete. It doesn't mean abandoning pipes and tunnels — it means making every piece of infrastructure work harder, work smarter, and work together.
Carol Haddock, vice chair of ASCE's infrastructure committee, has called for the creation of a nationwide stormwater asset database — a basic inventory of what we actually have. That we still lack one tells you everything about how little attention this infrastructure has received. "We need to understand what we have first, and that's a key first step," said Pat Lach, chair of Illinois's ASCE Report Card.
They're right. But the cities that aren't waiting for a national database — the ones already installing sensors, planting rain gardens, building AI-optimized green infrastructure, and proving that smart systems can cut overflows by 80 percent while saving hundreds of millions of dollars — are writing the playbook for everyone else.
America's stormwater infrastructure earned a D. But the technology to raise that grade already exists. The question isn't whether smart stormwater works. It's whether we'll fund it before the next flood proves, again, how expensive it is to do nothing.