---
title: Baltimore's Two Sewage Plants Reported 550 Million Gallons of Bypasses in 2026, the Most Since MDE's Database Began in 2023
canonical: https://marylandfeed.com/baltimore-sewage-plants-bypasses-2026/
published: '2026-10-30T14:00:01-04:00'
updated: '2026-10-30T14:00:01-04:00'
author: MarylandFeed Staff
section: Water & Sewage
places:
- Baltimore City
tags:
- Sewage Overflows
- Water Quality
- Department of the Environment
- Chesapeake Bay
source: Baltimore City Department of Public Works,
source_url: https://s3.amazonaws.com/baltimorecity.gov.if-us-east-1/s3fs-public/2026-08/BWW%20CD%20Report-August-15-2026.pdf
publisher: MarylandFeed
attribution: Copyright MarylandFeed. Quote with credit to MarylandFeed and a link to the canonical URL above.
---

# Baltimore's Two Sewage Plants Reported 550 Million Gallons of Bypasses in 2026, the Most Since MDE's Database Began in 2023

Baltimore City’s Back River and Patapsco wastewater treatment plants, the two largest in Maryland, reported 30 bypasses at the plants, in which wastewater was diverted from part of the treatment process, between Feb. 15 and July 18 of this year, totaling about 550 million gallons, according to the Maryland Department of the Environment’s overflow records. That is more than the two plants together reported in any full year since MDE’s current overflow database began in 2023.

The 2026 reports that name the part of the plant bypassed point to the final nutrient-removal filters, the stage that strips out nitrogen before the water is discharged into the Back and Patapsco rivers, both Chesapeake Bay tributaries. The three largest bypasses, 269 million gallons together, followed power failures or a tripped breaker.

The two plants accounted for about 550 million of the roughly 562 million gallons of bypasses reported statewide so far in 2026, a MarylandFeed calculation from MDE’s [Reported Sewer Overflows database](https://opendata.maryland.gov/dataset/Reported-Sewer-Overflows-New-for-2023-/stgj-u72u) on Maryland Open Data, downloaded Oct. 29. Back River reported 12 bypasses totaling about 281 million gallons and Patapsco 18 totaling about 269 million. These figures leave out two entries MDE files under Back River that describe sewer-line work away from the plant, about 561,600 gallons together.

In earlier years, the same records show about 5 million gallons of bypasses at the two plants in 2023 (the database starts that February), about 407 million in 2024 and about 208 million in 2025. The 2024 figure leaves out one Back River entry that the database itself labels a duplicate. The database lists no bypass at either plant after July 18. MDE says the volumes are reported by the plant operators and may be estimates.

## The largest bypasses this year

| Date | Plant | Gallons | Cause, as reported |
| --- | --- | --- | --- |
| July 18 | Back River | 118,000,000 | “Power outage at denitrification.” |
| May 6 | Patapsco | 78,030,000 | A control system breaker tripped, so filter cells “could not be backwashed” |
| July 5 | Patapsco | 73,100,000 | “the loss of power to the entire plant” |
| Feb. 20 | Back River | 39,000,000 | “problems with high solids” |
| Feb. 15 | Back River | 29,000,000 | “High flow” |

Source: Maryland Department of the Environment, [Reported Sewer Overflows (New for 2023)](https://opendata.maryland.gov/dataset/Reported-Sewer-Overflows-New-for-2023-/stgj-u72u), entries 219, 407, 257, 647 and 676, downloaded Oct. 29, 2026. Volumes are as reported to MDE.

Seven of the 30 reports name a power outage or loss of power as the cause, together about 256 million gallons. Two more, including the May 6 event at Patapsco, cite a tripped breaker. On July 18, both plants reported power-related bypasses: Back River’s 118 million gallons that morning and 5 million gallons at Patapsco that evening.

The 24-million-gallon Patapsco bypass on June 9, which the plant’s report blames on a “total plant power failure,” came the same day an electrical explosion injured three contractors at the plant, as [reported by CBS Baltimore](https://www.cbsnews.com/baltimore/news/explosion-baltimore-wastewater-treatment-plant-contractors-electrical-fault-dpw-says/).

## What a bypass means here

Back River’s state discharge permit defines a bypass as “the intentional diversion of pollutants from any portion of a treatment or collection facility” and prohibits one unless conditions in the permit are met ([permit 15-DP-0581](https://mde.maryland.gov/programs/water/Compliance/Documents/Final%20Permit%20for%2015DP0581A%20Post-modification.pdf), permit pages 2, 27 and 28). The records do not describe these as raw sewage releases. Several entries call them partial bypasses, and two Patapsco entries say the flow was disinfected; most entries do not say what treatment the water received.

At Back River, MDE’s report on a May 15 inspection notes concerns about the denitrification filter “being bypassed frequently since February of 2026 and up to April 2026” ([MDE joint inspection report](https://mde.maryland.gov/programs/water/Compliance/Documents/Back%20River%20WWTP/%287.18.2026%29%20Joint%20Report.pdf), PDF page 6). The same report explains the term “partial bypass,” based on a demonstration at those filters during the inspection:

![shot_backriver_dnf_partial_bypass.jpg](https://marylandfeed.com/media/2026/10/95660d40-shot-backriver-dnf-partial-bypass-1062.jpg)

Source: Maryland Department of the Environment, [joint inspection report on Back River WWTP](https://mde.maryland.gov/programs/water/Compliance/Documents/Back%20River%20WWTP/%287.18.2026%29%20Joint%20Report.pdf) (inspection May 15, 2026), PDF page 9, Denitrification Filters section.

For Patapsco, the city’s August consent decree report says that during bypasses from February to May, “the City continued to ensure the entire flow was disinfected and de-chlorinated prior to discharge to the Patapsco River.”

When Patapsco bypassed its nutrient-removal system in May 2025, sampling at the outfall showed elevated nitrogen and phosphorus going into the river, the [Bay Journal reported](https://www.bayjournal.com/news/pollution/more-polluted-wastewater-discharged-into-patapsco-river/article_fa1a59e8-b7b0-40f0-a574-4f7e4c80466a.html).

Baltimore’s Department of Public Works has described at least one of this year’s events publicly. After the first Back River bypasses on Feb. 15, a department spokeswoman told [Baltimore Brew](https://baltimorebrew.com/2026/02/19/amid-worsening-odor-from-the-back-river-plant-reports-that-sewage-sludge-has-been-backing-up-again/) the plant’s warning light was turned on “due to a temporary partial bypass of the denitrification filters, but all discharge remained within permit limits.”

## The consent decree’s penalty table

Both plants operate under a [consent decree](https://mde.maryland.gov/Documents/Executed%20Back%20River%20%26%20Patapsco%20WWTPs%20Consent%20Decree.pdf) signed in 2023 by MDE, Blue Water Baltimore and the city. It sets penalties for missed deadlines, effluent limit violations, monitoring failures and discharges “not authorized by a Discharge Permit,” and the city must list accrued penalties in quarterly reports.

The city’s [Aug. 15, 2026 report](https://s3.amazonaws.com/baltimorecity.gov.if-us-east-1/s3fs-public/2026-08/BWW%20CD%20Report-August-15-2026.pdf) lists 17 entries for 2026 across the two plants in its table of potential penalties for excursions and discharges: spills, sewer overflows, missed or invalid samples and limit excursions. None is a bypass. Back River’s only July 18 entry is a pH excursion. Since December 2023, MDE has applied $216,500 of $624,050 in potential penalties listed for the two plants, the table shows (pages 6 to 8).

![Back River’s 2026 entries in the potential penalty table, with the table’s header (rows from pages 6 and 7, joined).](https://marylandfeed.com/media/2026/10/a2ae8e95-shot-backriver-penalty-table-2026-1082.jpg)

Back River’s 2026 entries in the potential penalty table, with the table’s header (rows from pages 6 and 7, joined). Source: Baltimore City Department of Public Works, [Consent Decree Quarterly Report, Aug. 15, 2026](https://s3.amazonaws.com/baltimorecity.gov.if-us-east-1/s3fs-public/2026-08/BWW%20CD%20Report-August-15-2026.pdf), Table 3.

MDE and the U.S. Environmental Protection Agency inspected Back River together on Sept. 9 and 10, and MDE says the report “will be published and shared once finalized,” according to [slides from MDE’s Sept. 24 community meeting](https://mde.maryland.gov/programs/water/Compliance/Documents/Back%20River%20WWTP/%2809.24.26%29%20Back%20River%20Community%20Meeting.pdf). The same slides say Back River’s new discharge permit “should be issued by the end of this year.” MDE also keeps a separate [Back River bypasses dataset](https://opendata.maryland.gov/Government/Back-River-Bypasses/cjgx-jscg), which it says is updated within 24 hours of the city’s notice.

Source: [Baltimore City Department of Public Works,](https://s3.amazonaws.com/baltimorecity.gov.if-us-east-1/s3fs-public/2026-08/BWW%20CD%20Report-August-15-2026.pdf)