DETROIT — Although Detroit has 1 billion to 3 billion gallons of sewage fouling its local rivers and streams each year — and eventually Lake Erie — that’s a huge reduction from the 25 billion-gallon-a-year average dumped in the lake in 1993.

Most of the largely untreated waste goes into the Detroit River and the River Rouge, which flow into western Lake Erie.

Detroit always will be a focus of concern, according to experts on both sides of the Michigan-Ohio border, for the simple fact it has one of the world’s largest wastewater treatment systems. It also has had a long history of compliance issues related to equipment and other issues.

But Michigan officials said the city is doing its part to protect western Lake Erie by modernizing its sewage network.

They have spent $1.2 billion so far to modernize and expand Detroit’s sewage network in recent years, and plans for considerably more work between 2019 and 2037.

Michigan Department of Environmental Quality officials said much of that focus is on capturing the mixture of stormwater and household waste — known as combined sewer overflows, or CSOs — that overwhelm its sewage network during heavy storms.

If not released into waterways, the foul water backs up and floods basements.

Toledo has the same problem — on a smaller scale — and has spent $521 million on the Toledo Waterways Initiative that began about 13 years ago. When completed in 2020, the work is expected to curb sewage spills into the Maumee and Ottawa rivers and eventually Lake Erie by 80 percent.

Such spills are hardly unique to Detroit or Toledo.

Combined sewers

According to the U.S. Environmental Protection Agency, there are 772 cities and towns across the nation with combined sewers, many of them in older Midwestern cities. In most cases, the raw sewage spills into America’s rivers and streams before it reaches local sewage-treatment plants to be disinfected for bacteria and have its levels of algae-producing phosphorus reduced.

Ohio has 71 of those communities, according to Ohio EPA figures.

Susan Hedman, U.S. EPA Midwest region administrator, said the agency has “enforceable agreements” with 66 Midwestern communities to fix CSOs.

Negotiations are under way to finalize agreements with six other Midwestern communities within the next year: Peoria, Ill., Gary, Ind., Hammond, Ind., Elyria, Ohio, Lakewood, Ohio, and Middletown, Ohio, she said.

In many cases, the agreements are consent decrees made binding by a federal judge.

The issue predates the 1972 federal Clean Water Act, the landmark federal law that is most often used as the benchmark for today’s modern era of sewage treatment.

As far back as 1910, former President Theodore Roosevelt addressed the subject.

“Civilized people,” Mr. Roosevelt said at an event in Buffalo, “should be able to dispose of sewage in a better way than by putting it into drinking water.”

A massive system

The Detroit Wastewater Treatment Plant processes 930 million gallons of sewage a day, making it one of the world’s largest.

A trade publication, Engineering News-Record, has ranked it third behind facilities in Chicago and Boston. But Chicago’s facility in Cicero, Ill., is divided among two plants and serves fewer people — 2.4 million in Chicago and 43 suburban communities. Detroit’s has a huge geographical footprint of 946 square miles. It serves 3.5 million people and 76 surrounding communities, in addition to the city of Detroit.

Under Detroit’s most recent five-year permit — issued in 2013 — the treated effluent discharged from the plant under normal operating conditions cannot have more than 0.6 parts per million of phosphorus in it.

Since adding ferric chloride to the pretreatment process, the concentration has been considerably less, about 0.2 ppm to 0.3 ppm, said William Creal, Michigan Department of Environmental Quality water division chief.

As geeky as those numbers sound, they’re becoming another part of the infamous Michigan-Ohio rivalry.

Michigan is calling upon Ohio to follow its lead and limit phosphorus discharges from sewage-treatment plants in the Buckeye State to 0.6 ppm, with the idea being that would give algae less to feed on, Mr. Creal said.

Although Toledo’s permit and those of many other Ohio wastewater treatment plants allow phosphorus concentrations of up to 1.0 ppm during normal operations, records show Toledo’s average annual discharges from 2010 to 2014 were right on the 0.6 ppm mark, with a high of 0.73 ppm and a low of 0.44 ppm, said Dina Pierce, Ohio EPA spokesman.

And according to records provided by the city of Toledo, this year’s phosphorus concentration from the plant, through September, was 0.40 ppm, the lowest in years.

Ms. Pierce’s supervisor, Heidi Griesmer, the agency’s deputy director of communication, said Ohio plants — with few exceptions — are allowed to release up to 1.0 ppm of phosphorus in their discharges. She did not say if the agency would consider lowering that limit.

Catch basins

But what about combined sewer overflows?

Phil Argiroff, Michigan DEQ permits section chief, said the core program for addressing those in the Detroit sewage network has been accomplished through the construction of nine catch basins built between 1997 and 2012, several of which screen out large particles and are designed to have chlorine injected so that the overflows are at least partially treated.

More water also has been moved to the treatment plant as it has been expanded, further reducing overflows, he said.

The sewage system has been on a long-term control plan since 1996.

It is now in an assessment phase. 

Starting in 2019, more improvements will be required every five years under future permits through at least 2037. They will likely include green infrastructure projects designed to capture overflows and treat wastewater with less energy, Mr. Argiroff said.

“There are likely to be more engineered storage facilities constructed,” he said.

Jodi Peace, Michigan DEQ senior environmental quality analyst, said the role of green infrastructure is to save the city money in the long-run by using less energy.

About $15 million is expected to be spent on that type of work over five years, an average of $3 million a year, Ms. Peace said.

“If you stop that stormwater from getting into the system, there’s less to deal with,” she said.

Scientists have attributed only 5 percent of western Lake Erie’s phosphorus to the Detroit Wastewater Treatment Plant while acknowledging the research is preliminary.

In a statement to The Blade on Friday, the city of Toledo — citing National Oceanic and Atmospheric Administration data — said it believes only about 2 percent of western Lake Erie’s phosphorus comes from the Toledo wastewater treatment plant’s effluent and area sewage spills.

Great Lakes scientists have said 60 percent to 80 percent of it comes from agriculture, mostly from the Maumee River.

Source of issues?

The Kasich administration raised questions about the Detroit Wastewater Treatment Plant following western Lake Erie’s record algal bloom in 2011. Some critics questioned if that was an attempt to deflect criticism away from northwest Ohio agriculture.

“We’ve done a lot. The place where the bulk of pollutants are coming from is ag runoff,” Ms. Peace said.

Research presented to the International Joint Commission, a binational agency advising the United States and Canadian governments on boundary water issues since 1909, also suggests Detroit River phosphorus is more likely carried out in currents to the lake’s central basin than adding to the phosphorus in the western basin, which is believed to come primarily from the Maumee and Sandusky rivers.

Laura Johnson, Heidelberg University research scientist, agreed the sheer volume of waste being moved through the Detroit Wastewater Treatment Plant can never be discounted — but said the figures don’t bear out a strong correlation, especially if algae’s rising while daily phosphorus discharges from the plant and combined sewer overflows are declining.

“That’s in the face of more intense precipitation,” she said, a reference to higher-intensity storms in recent years from climate change. “If they’re going down [with CSO releases] in the face of that, they’ve done a lot of work.”

Downstream from Detroit lies a research project that has Ms. Johnson and other scientists puzzled — a doubling of dissolved reactive phosphorus in the River Raisin since the 1990s, the type of phosphorus that promotes the fastest algal growth. That river, which flows into western Lake Erie at Monroe, is mostly affected by agriculture.

Some environmentalists, such as Sandy Bihn, Lake Erie Waterkeeper founder, question if Detroit’s improvements have been embellished by the administration of Gov. Rick Snyder for political reasons.

Ms. Bihn recently advised Toledo mayoral candidate Mike Ferner to keep up the pressure on the Detroit Wastewater Treatment Plant during his campaign.

“I am not sure I trust anything from MDEQ,” Ms. Bihn said, noting recent news reports about harmful lead contamination in the Flint water supply.

She and Mr. Ferner want western Lake Erie to be declared a distressed watershed so that pollution sources can be better identified through a federal program that focuses on total maximum daily loads of nutrients, and an accountable implementation plan would be required for more consistency. 

One of the nation’s models for that is the Chesapeake Bay, where several states work with the federal government to address it more as an ecosystem.

Ms. Bihn said she would like to see Detroit required to hold and eventually treat all of its waste.

Instead, she said, it is “just chlorinating and releasing because the plant is so large.”

Contact Tom Henry at: thenry@theblade.com, 419-724-6079, or via Twitter @ecowriterohio.

First Published October 18, 2015, 4:00 a.m.