By Mike Anderson
Have you caught a whiff of the air coming off South Mill Pond? That’s not low tide you’re smelling. South Mill Pond is a dumping site for sewage overflows, and this year, the City has released more contaminated water than over the last few years combined. The City mysteriously failed to warn residents about these discharges, despite having an alert system designed to do just that. It’s a stinky situation, especially for Portsmouth residents whose water and sewer rates are the highest in New Hampshire.
Portsmouth is an old town with old sewer pipes. The city began replacing its old system, in which sewage and water ran in the same pipes, in the 1960s. Unfortunately, some combined sewer pipes remain. When there’s too much rain, the volume of water is more than the old combined system can handle, and some of it must be released. The releases are known as Combined Sewer Overflows (CSOs). Two overflow sites, 10A and 10B, discharge this untreated water into South Mill Pond. Another location dumps water from CSOs into the Piscataqua River.
The Environmental Protection Agency allows this practice in cities with old, combined sewers, as long as cities have Long Term Control Plans (LTCPs) to upgrade systems. Work completed under previous LTCPs has resulted in fewer CSOs and has reduced sewer backups into basements, according to the City’s website. The City has also reduced the number of CSO sites from 14 to three.
That’s the good news. The bad news is that the City’s equipment has failed to handle large volumes of water. Portsmouth spent nearly $100 million on the Peirce Island wastewater facility (the largest municipal project in the City’s history), but improvements were not made to the pump station at Mechanic Street. The City is using temporary pumps there while its permanent pumps are down for repairs. A third, redundant pump was never added, and the temporary pumps appear to be unable to handle heavy volumes from severe rainstorms. The water has to go somewhere, and this may be the source of this year’s unusually large CSO discharges.
Portsmouth ratepayers might want to know why the pumps weren’t maintained or repaired before 4 million gallons were released in January and another 2 million in May (Combined Sewer Overflows (CSO) | City of Portsmouth). They might also wonder why they weren’t notified. The City has an alert system to notify residents about CSO discharges, but the system failed to do that. As of the writing of this story, the Department of Public Works had not responded to a request for information about the source of the recent CSO releases and the alert system failure.
The City does acknowledge the public safety issues created by its sewage overflows. Its website advises against swimming in ponds where sewage is dumped for 48 hours after a rainstorm. South Mill Pond also has two small signs indicating the location of the CSO discharges and a “no swimming” symbol.
Just how dirty is the water? A study completed by engineering consultants for the city found that sewage dumped into South Mill Pond contained 150 milligrams per liter of Total Suspended Solids (TSS). This measurement includes human waste as well as sand and silt. For one million gallons of CSO released in the pond, 1,300 pounds of “wastewater solids” are also released. That adds up to 8,000 pounds for the 6 million gallons discharged in 2023 so far. The “mud” along the banks of South Mill Pond isn’t just mud, as the presence of toilet paper in the water demonstrates.
The pollution of South Mill Pond is no secret, but the City’s approach to dealing with it is obfuscating. On one hand, the City acknowledges the hazards, but on another, seeks to minimize them. The upcoming Lantern Festival is a case in point. The Portsmouth 400 celebrations include an evening event at the pond, in which families will decorate lanterns to float on the surface of the water. Imagine the optics of children wading through the layers of fecal waste to launch their carefully decorated lanterns, then walking back to their families with toilet paper clinging to their shoes. Imagine also the optics of admitting the extent of the pollution and canceling the event. Not to worry – volunteers, wearing boots and gloves will launch the lanterns.
An ongoing concern about pollution from CSOs is the contamination of local beaches. Last year, the beach at Great Island Common was under advisory for fecal bacteria contamination for 21 days of its 100-day season. These advisories do not require the beaches to close, but indicate that the water is unsafe for swimming or exposure. In early August, fecal bacterial advisories were posted at four New Hampshire beaches: North Hampton State Park Beach, Griffin Beach, Clough State Park Beach, and Pirate’s Cove (see https://www.wmur.com/article/new-hampshire-beaches-fecal-bacteria-advisory-823/44744710).
While it may be impossible to pinpoint the exact source of fecal bacteria at nearby beaches, the pollution is coming from somewhere. With its massive investment in the Peirce Island facility and its voluntary designation as an “eco-municipality,” one would expect Portsmouth to lead the way to cleaner, safer water and beaches.
In the 1800s, the City ran its sewage directly into tidal ponds, hoping the tide would carry the waste out to sea. It’s taken decades of work and millions of dollars to build a better but incomplete system. The City’s proposed budget looks like one more massive overflow. Maybe some of the money could be used to repair the pumps or resolve problems with the alert system. But that’s an idea that probably will go out with the tide.
