Guest Author: Tom Barrett, GreenWater Infrastructure

Have you ever received one of these notices from Citizens Energy Group? They’re issued at least 50 times per year, to advise Indianapolis residents to “avoid all contact with streams for the next 4 days,” due to raw sewage overflowing from our antiquated sewer system.

How Our Sewer System Works

Indianapolis, like most older U.S. cities, uses an outdated Combined Sewer Overflow (CSO) system. The CSO blends sewage and storm water runoff together as they filter into treatment plants.

Sewer systems are primarily powered by gravity. Pipes from each house or building flow to a 3- to 5-foot-wide sewer main that typically runs down the middle of the street.

The sewer mains flow into progressively larger pipes until they reach the treatment plant. (In order to help gravity do its job, the wastewater treatment plant is usually located in a low-lying area.) In Indianapolis, primarily in Center Township, the stormwater pipes connect to the wastewater (i.e., sewage) pipes for an area covering approximately 55.5 square miles.

The problem arises when Indy receives rainfall. As little as a quarter of an inch of precipitation is enough to overwhelm the CSO systems, overfilling holding tanks and allowing the untreated sewage to run unchecked into the White River.

Need to Clean Up Our Act

In 2006, the City of Indianapolis was cited for failure to comply with the Clean Water Act, specifically in connection with the city’s operation of its municipal wastewater and sewer system. At that time, the EPA and the U.S. Department of Justice reached a consent agreement with the City to eliminate 97% of combined sewer overflow by 2025.

“Indy is obligated to remove a certain amount of sewage by stopping overflows from the CSOs,” according to Molly Deuberry, director of communications for the state’s Department of Public Works.

We’re Not Alone

The Indianapolis area is not by any means alone in its CSO woes, as the map below demonstrates. Combined sewer systems are found in approximately 860 municipalities across the U.S., mostly concentrated in the Northeast, Mid-Atlantic, and Great Lakes states.

Some date as far back as the late 19th century, when a number of municipalities began installing public sewer systems. Faced with a choice between combined and separated sewers, many communities opted for the former option because it was cheaper—and, at the time, it was believed to be just as safe.

“It was not until early in the 20th century that engineers fully recognized that an adequate stormwater drainage system was necessary to protect the sanitary sewer system,” an EPA representative recently stated

But the news came too late for Indianapolis, New York, Philadelphia, and other cities that had already constructed elaborate combined sewer systems.

Is Dilution Really the Solution?

For decades the traditional approach to water pollution management in Indianapolis and elsewhere has been summed up in the mantra, “The solution to pollution is dilution.”

The logic here is that sufficiently diluted pollution is not harmful. But this assumes that the diluting component is in virtually unlimited supply, and that the resulting dilutions are always acceptable.

Back in the day when human population and densities were lower, technologies were simpler and their byproducts more benign. The dilution solution may have been more practical then.

But this is no longer the case. Chemicals used in industry and agriculture have been added to the mix. Many of these substances cannot be broken down naturally or biodegraded.

Besides, technical advances have enabled the measurement of concentrations of pollutants which were not possible before. In other words, we now know that, even after dilution, there’s stuff in the water you wouldn’t want to drink.

And yet, the dilution approach to water pollution still predominates in Indy and throughout the world.

Can You Dig It?

In keeping with this approach, Indy’s answer to its CSO issues has been to dig bigger and deeper tunnels to handle the runoff. Dubbed “DigIndy,” the sewer project will be a 28-mile network of 18-foot rock tunnels built 250 feet beneath the city.

Once completed, the tunnel will stretch from the Southport Advanced Wastewater Treatment Plant to the Belmont Advanced Waste Water Treatment Plant, in the 2700 block of S. Belmont Avenue. It’s expected to cost $1.9 billion.

Here’s the DigIndy promotional video:

Surprisingly, digging larger tunnels is the “remedy of choice around the world for dealing with runoff issues.” That’s according to the Indianapolis Business Journal’s Sam Stall. Although even Stall had to admit that, “Digging a giant tunnel to store it all sounds like the sort of solution a 5-year-old might concoct.”

One has to ask, is digging a giant tunnel really the best solution to Indy’s sewage overflow problems?

The Dreaded E. Coli

Some experts don’t think so.

For instance, dilution may not be the answer to one particular Indianapolis-area pollutant that clearly needs to diminish: E. coli. Right now, approximately 80% of streams in the Indianapolis watershed are contaminated with it, thanks to our combined sewer overflow.

Former IUPUI geologist Lenore Tedesco has warned of the CSO’s long-term effects with respect to E. coli.

“Floaties don’t float for long,” she stated in reference to the raw sewage. “They sink, they settle. All that stuff gets trapped behind dams. That’s not going to go away just because they stopped adding to the pile.”

A Watershed Issue

Tedesco and other local experts think addressing the CSO problem as a comprehensive watershed issue would be a better long-term approach. All pollutants, including the sewage overflow, need to be considered.

Indianapolis is part of Upper White River Watershed (UWRW) which encompasses a 2,720 square mile area (1,740,544 acres) within central Indiana. It extends across sixteen counties. The UWRW consists of seventeen smaller subwatersheds.

When rivers and streams from the various counties merge within the watershed, they combine with farmland pesticides and urban pollutants accumulated along the way.

“I can tell you right now, the water quality coming into Marion County does not meet state standards,” Tedesco said. “It’s already polluted.”

The main sources of pollution in these waterways aren’t large corporations. In fact, Tedesco believes it’s the average citizen who inflicts the most damage upon our water supply.

Clear Choices, Clean Water

In order for individuals to start reining in their harmful impact, Tedesco said, education is key.

“Getting every person to understand that their little plot of land… is part of a watershed and, ultimately, part of our water quality, is important,” she explained. “You have to have a community buy-in.”

To that end, “Clear Choices Clean Water” is an Indianapolis campaign designed to increase awareness about choices we make and the impacts they have on our streams and lakes.

The group advocates water-friendly practices such as landscaping with native plants, using phosphate-free fertilizers, managing yard and pet wastes, maintaining septic systems, fostering soil health, and using less water.

For instance, pet owners need to be educated on the importance of picking up dog waste. When left on the ground, fecal matter washes into the river, adding to the E. coli problem that already plagues our waterways.

The Disconnect

Despite some minimal progress made in recent years, Tedesco identified a widespread problem in the city’s approach to water pollution.

“My biggest concern is that the general public does not see a linkage between source water, its quality, and their health and wellbeing,” she said.

To increase that community awareness from the ground up, Clear Choices Clean Water urges Hoosiers to visit their website, at, where they can learn about all the ways individuals can make a difference.

“Water is a resource. It’s not unlimited and it’s something that has to be managed,” she continued. “It has to be cherished. Our water resources have to be cared for.”




IUPUI Center for Earth and Environmental Science,


Pollution Issues,


Indianapolis Business Journal,




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