On August 13th, New York State witnessed the greatest 24-hour rainfall, 13.27 inches, in its recorded history. The state record – last set in 2011 – was broken in West Islip, Long Island, fewer than 30 miles from the Queens border.

A flash flood watch went in effect throughout New York City, and beaches in Brooklyn and Staten Island were closed to swimmers the following day. The heavy rain had overloaded sewer mains, necessitating the release of untreated sewage directly into local waterways.

If the City’s climate scientists are right, New York will steadily become a wetter city, subject to more frequent and intense rainfall – and thus, more overloaded sewers and water-related health risks.

And at the very same time that New York’s climate is shifting, the City is engaged in what will be a decades-long effort to address a long-standing problem: the need to capture stormwater before it overwhelms sewers and treatment plants, triggering the release of untreated sewage into Jamaica Bay, the Bronx River, and other waterways.

Average annual precipitation currently ranges between 43 and 50 inches in New York City, depending on location. The New York City Panel on Climate Change notes that, between 1900 and 2011, precipitation in Central Park increased about .7 inches every decade.

Almost 30 billion gallons of raw sewage and polluted stormwater are discharged annually into New York City’s waterways.

And perhaps more importantly, in its Climate Risk Information 2013 report, the Panel adds that “larger percentage increases are expected in the frequency, intensity and duration of extreme precipitation.” The Panel defines an extreme precipitation event as one with more than 1 inch of rain.

Today, as little as a quarter-inch of rain can overwhelm municipal sewers. The end result of extreme – and not so extreme – weather is ongoing contamination of our local environment. Almost 30 billion gallons of raw sewage and polluted stormwater are discharged annually from over four-hundred combined sewage overflows (CSOs) into New York City’s waterways.

The scale of the problem that the City is trying to solve is “huge,” said Larry Levine, a senior attorney with the Natural Resources Defense Council’s water program.

An Over-Taxed Wastewater System

Climate change adds a further layer of complication to what has already been a pressing problem for New York City: stormwater management.

The de Blasio administration is working to address two parallel issues. First, large sections of the city rely on what is now considered an outmoded sewer system.

[A second, entirely separate issue is the fact that areas of the city like Staten Island’s east shore and sections of eastern Queens do not even have proper storm drains. These communities were developed on an “ad-hoc basis”, often in low-lying, marshy areas. Neighborhoods like New Dorp Beach and South Beach on Staten Island, which were devastated by Superstorm Sandy, are now racing against time to put stormwater infrastructure into place.]

Much of the city, however, relies on what is known as a combined sewer system. Household and industrial wastewater, rainwater, and street runoff are all collected in the same sewers and then conveyed together to the City’s treatment plants. Approximately 70 percent of New York’s sewers are combined says the City.

New York City’s 14 wastewater treatment plants together treat 1.3 billion gallons of wastewater daily. The City says it is able to remove about 85% to 95% of pollutants from wastewater before it is disinfected with chlorine and then discharged back into local waterways.

But during heavy rains or snow, combined sewers can fill to capacity and are then unable to carry household and storm sewage to treatment plants. The mix of excess storm water and untreated sewage must be released directly into the city’s waterways.

Find the CSO release site closest to you.

Major Improvement but Water Quality “Failures” Persist

There are two equally valid stories to be told about the quality of New York City’s waterways, which is heavily impacted by stormwater management.

On the one hand, water quality has improved significantly; to the point where swimmers, kayakers, and other recreators are seen with greater frequency in more and more sections along the city’s coastline. Wildlife has also responded to improvements in local water quality.

Indeed, New York City residents might be surprised to see the results of a recent six-year study which looked at 15 Hudson River estuary sites in the five boroughs. The majority of samples collected from sites like the Dyckman Street Beach in the Bronx, the Pier 96 Kayak Launch, and the Battery found that the water was safe for swimming.

The study, carried out by Hudson Riverkeeper, in conjunction with CUNY Queens College and Columbia University’s Lamont Doherty Earth Observatory, actually collected data from 74 estuary locations between New York Harbor and Waterford, Saratoga County.

Nonetheless, the other story is that one-quarter of the water samples collected from the 15 New York City estuary sites failed U.S. Environmental Protection Agency “safe swim guidelines” for fecal contamination.

Last year, New York ranked 20th in beach water quality out of thirty states.

Perhaps more telling, the percentage of failing New York City samples jumped from ten percent in dry weather to thirty-five percent after wet weather. Wet weather was defined as at least one-quarter inch of cumulative rainfall in the preceding three days.

The entire state is facing similar issues. Last year, New York ranked 20th in beach water quality out of thirty states, the Natural Resources Defense Council found. Thirteen percent of samples collected at local beaches throughout the state exceeded EPA “safe swim” bacterial levels.

Combined sewage overflow (CSO) releases are seen as a primary culprit in local waterway fecal contamination.

Toxic Releases and Their Impact

Untreated human waste, and the pathogenic bacteria and viruses that come with it, is the most well known component of CSO discharges. The most common illness associated with swimming in sewage-polluted water is gastroenteritis, says the EPA.

Gastroenteritis occurs in a variety of forms that can have one or more of the following symptoms: nausea, vomiting, stomachache, diarrhea, headache or fever. Children, the elderly and people with weakened immune systems are most at risk.

Swimmers and others who cross paths with a CSO release can encounter debris flushed down toilets (syringes, tampon applicators, etc.) and trash washed off city streets. Any substance on city streets, or poured down storm drains, can end up in a CSO.

Riverkeeper’s website provides a disturbing list of compounds that have been found in CSOs: ammonia; pesticides; petroleum products (from gas stations and auto repair shops); toxic metals; and other hazardous substances like paints, oils, solvents and cleaners.

CSO discharges can also damage local ecosystems because their elevated nutrient content can combine with hot weather to create dangerous toxic algae blooms. These blooms are extremely hazardous to humans and animals, and can create “dead zones” in local waterways.

Similarly, CSO releases containing food waste, and dead plant and animal tissue, deplete oxygen needed by fish and plant life to survive.

Trouble in the Gowanus

Gowanus canal detritus. Photo credit: Anthony Fine/Creative Commons.

CSO releases into the Gowanus Canal in Brooklyn have been documented for years by local residents who say that the canal becomes “one huge toilet” after a major rainfall.

“Last night’s [July 2nd, 2014] heavy rain caused another Combined Sewer Overflow event,” wrote neighborhood resident and local blogger Katia Kelly.

“By 11 PM, much of the waterway was covered with raw sewage. The smell was unbelievable…It is unfathomable to think that the new residents of the 700 unit Lightstone Group Project at the shores of the canal will have to deal with this every time it rains heavily.”

In the aftermath of the July 2 storm, and following other major downpours, residents in the nearby Gowanus Houses public housing development have also reported that raw sewage backs up into their kitchen sinks.

One of those residents happens to work for local City Council Member Steve Levin. Levin said that he had spoken with the City’s Department of Environmental Protection and the Housing Authority about the back-ups. “It’s hard to say what’s going on,” he stated, but added that he believed the back-ups were caused by “some combination” of the CSO releases into the canal, and plumbing issues within the development itself.

Levin stressed that NYCHA had been very responsive in dealing with similar issues at other developments in the area. He also noted that long-term clean-up plans for the Gowanus Canal included “sewage holding tanks” that would help to control the releases.

“We would like to see as much of an effort as possible,” Levin said, “to determine what’s going on in the intervening years before all of the [sewage management] infrastructure is implemented.” He said it would be “helpful” if DEP could examine all of the existing infrastructure in the surrounding area and “make sure that everything is in good repair.”

Neither the DEP nor the state Department of Environmental Conservation would respond to questions for this story about CSO releases into the Gowanus Canal, or sewage back-ups at the Gowanus Houses.

The Public’s Right to Know

Residents in Gowanus and other neighborhoods cannot obtain real-time information on rain-related releases from individual CSOs, despite 2012 state legislation requiring “publicly owned treatment works to report discharges of untreated or partially treated sewage.”

According to state law, residents must be notified within four hours of a sewage overflow. The state DEC must report the estimated amount of the overflow, the location and duration, the reason, and a description of steps taken to control the release from happening again.

The lack of publicly-available data on rain-related CSO releases is technically a violation of state law, said Phillip Musegaas, an attorney with Riverkeeper and director of its Hudson River Program. But, he added, there is a straightforward reason for the lack of data: the City does not know exactly how much sewage is coming out of each of its 426 CSO release points during rain events.

The City estimates the size of releases using modeling based on the amount of rainfall and the impact of similar rain events in the past. City residents can check online to see if a water quality advisory has been issued for their area.

Some of these “areas” are very broad, encompassing multiple neighborhoods, and making it hard to know what is happening at the local level. Musegaas said that Riverkeeper has repeatedly raised the problematic nature of this method of tracking with the City to no avail.

“Why not install monitors on the biggest CSO’s? Pick twenty or thirty,” said Musegaas.

Musegaas added that climate change also made the use of modeling more questionable. “If you’re basing your modeling on one place [rainfall measured at LaGuardia Airport] and one year, that’s a problem.”

Why does the lack of data about releases of raw sewage into an already polluted waterway like the Gowanus matter? “The thing that’s going to make you actually physically ill is what comes from the CSOs – it’s raw sewage,” said Council Member Levin.

Neither the City nor the State responded to questions about how releases from CSOs across the city are tracked.

Some communities living close to CSO release points are taking the lack of real-time data into their own hands. The Newtown Creek Alliance is now attempting to track local CSO releases and alert area residents by text message when flushing their toilets will send waste directly into the creek.

It is important to note that, during the summer months, the City collects and then publishes weekly data about water quality in 70 locations across the five boroughs. The data is published on a monthly basis the rest of the year. The latest available data is from August 18th through August 21st.

What’s the Goal? The City and State Face Off on Water Quality Standards

CSO discharges operate in a grey area relative to federal and state clean water regulations. They are essentially pollution releases that are managed by government.

“The City is supposed to reduce [these releases],” said Larry Levine of the NRDC. “What would be illegal is if they don’t follow through on specific plans [to reduce volume].”

And the City is actively working on a long-term plan to reduce CSO releases based on a series of “Consent Orders” it has entered into with the State. In the next three years, the City must produce plans for ten separate water bodies or “sewer sheds” – areas of the city where raw sewage is released into waterways.

According to the City, the goal of each plan “is to identify appropriate CSO controls necessary to achieve waterbody-specific…standards, consistent with the Federal CSO Policy and the water quality goals of the Clean Water Act.”

The areas targeted for CSO reduction are: Alley Creek, the Hutchinson River, the Bronx River, Coney Island Creek, Flushing Bay, Flushing Creek, the Gowanus Canal, Jamaica Bay and its tributaries, Newtown Creek, and Westchester Creek.

The ten area plans will eventually form the basis of a citywide CSO reduction plan.

However, the state DEC has rejected the first long-term plan submitted by the City, which covers Alley Creek in Queens. At issue is to what extent the City actually plans to clean-up Alley Creek. The City aimed lower than what the State says is required by federal law.

“The City’s proposed long-term CSO control plan unlawfully failed to identify CSO controls that would either clean up Alley Creek enough to allow full fishable/swimmable use or, if that were not attainable, clean up Alley Creek enough to allow…[that] use on a seasonal basis,” Attorney General Eric Schneiderman wrote in a document filed with the New York State Supreme Court this June.

The City “misses the mark,” said Schneiderman, by attempting to only adhere to state water quality standards that are not as stringent as federal standards. “Under the federal Clean Water Act, DEC’s regulation of pollutant discharges to such water bodies as Alley Creek, can be no less stringent than the requirements set by federal law.”

The water quality standards that are ultimately established for Alley Creek could set the tone for the nine other waterbody plans to come, said Levine. The State and the City are now in litigation.

‘Green Infrastructure’ Will be Key

The State and the City have reached agreement, however, on the use of green infrastructure to “improve the overall water quality in New York Harbor waters.”

The idea is to capture and make use of rainwater at the source, before it enters the city’s combined sewer system. By changing its fundamental approach to stormwater management, the City is not only reducing pollution levels in local waterways, it is also preparing for climate change.

A State order requires that by 2030 the City be able to divert the first inch of rain from 10 percent of New York’s impervious surfaces using a green infrastructure “adaptive management approach.”

Examples of green infrastructure projects include: blue roofs and green roofs, which use mechanical devices or vegetation to slow roof water from draining too quickly; porous pavement for parking lots so water can be absorbed into the ground; tree pits and streetside swales for roadways so water can pool in underground holding areas and dissipate in the ground or through plants; wetlands and swales in parks; and rain barrels in some residential areas.

The State’s order requires five-year incremental milestones to meet the 10 percent target, and annual reporting on progress. The City has committed $187 million toward meeting the first five-year target in 2017.

And the City says it will utilize an estimated $2.4 billion of public and private funding over the next 18 years to install more green infrastructure technologies. Through the order, the City maintains flexibility to prioritize green investments in neighborhoods that it says “will benefit most from reductions in combined sewer overflows.”

How much of a difference can green infrastructure make?

The City estimates that its use could lead to the annual removal of approximately 1.5 billion gallons of CSO releases by 2030. Roughly 8.4 billion gallons could be removed by 2045, using green and “targeted” gray infrastructure.

That’s almost one-third of the estimated 30 billion gallons released by CSOs each year.

“Green infrastructure is the right solution,” said Larry Levine. “The City is making some serious progress.” But, Levine cautioned that solutions to the city’s wastewater problem are going to be “long-term.”

And, Levine added, the City “should improve its stormwater management standards for new development projects.” Standards for new buildings should require on-site management – through green infrastructure, not discharge into sewers – “of at least the first one-inch of rainfall in any storm,” Levine said.

A similar approach is already mandated in other parts of New York State.

Instead, the City requires new development sites “to temporarily hold on to runoff and then release it slowly into sewers,” says Levine. “That approach helps to reduce overflows but, by the City’s own calculations, it’s much less effective than keeping that runoff out of the sewers entirely,” he concluded.

The pressure to address stormwater management is unrelenting. At the time this article was being finalized for publication, a flash flood warning was issued for New York City. “Rain rates up to 2 inches per hour are expected,” said the National Weather Service.

And climate change makes the goal of a truly sustainable city – one which no longer pollutes the environment around it – both more challenging and more urgent at the same time.

Is it reasonable to expect that all of the city’s waterways should eventually meet the federal requirement that they be swimmable and fishable?

“Absolutely,” responded Phillip Musegaas. “That’s what the Clean Water Act calls for…to make sure that these public resources are healthy…It’s a good goal to have.”