(December 22, 2021) After months of review and discussion, Massachusetts has finally worked out a plan for how it will alert the public when sewage treatment plants release untreated and partly-treated sewage into rivers such as the Merrimack.
The plan was finalized Tuesday, and will go into effect in July 2022.
State lawmakers passed a bill in early 2021 that requires sewer plants to quickly inform the public whenever they release untreated sewage into a public waterway. The bill laid out many basic goals, but it left it up to the Department of Environmental Protection to work out the details.
Below we’ll report on what this new law will do, but first, some background.

Why was the law passed?
The release of partly or untreated sewage into the Merrimack has been occurring for many decades. Although sewer plants exist along the entire river, some are not capable of handling all of the flow that comes into sewer pipes during rainstorms. This is a remnant of 19th century engineering, and is extremely expensive to fix. It’s also not unique to the Merrimack — across the nation there are hundreds of plants that release sewage into waterways.
Several states have laws on the books mandating these events be reported to the public as a way to protect public health. Up until this year, Massachusetts had no reporting requirements.
In Massachusetts, the alert bill had been proposed and defeated several times in the past, but the issue reached critical mass in early 2019 due in large part to concern over what was happening on the Merrimack River. In 2018, some 850 million gallons of untreated sewage (known as Combined Sewer Overflows or CSOs) was discharged into the Merrimack from municipal sewer treatment plants in Lowell, Haverhill, greater Lawrence, and two plants in New Hampshire – Nashua and Manchester. That’s significantly higher than the annual average, which is about 510 million gallons. The 2018 increase was due to a series of heavy rainstorms that overwhelmed the sewer systems and led to huge discharges of untreated wastewater.
Public outcry over CSOs in the Merrimack Valley was loud and effective, and that helped push the bill over the finish line.
The law applies only to the plants in Massachusetts. Currently there is no legislation proposed in New Hampshire to require plants to improve their public reporting of sewage releases. Both New Hampshire plants report their releases, but not nearly as completely as the Massachusetts plants will be required to report.

What’s in the law
The public will be alerted when untreated or partly treated sewage enters a public waterway. The most common occurrence of this on the Merrimack is what’s called “blended” or “high flow” releases – a combination of fully and partly treated sewage. The amount of harmful bacteria in these releases is diluted, and up until this law was passed these incidents were not being reported when they occurred. The second most common (and better known) release is a CSO, which is untreated sewage. It generally has a much higher concentration of harmful bacteria than “high flow” events. Finally, “SSO” events will also be reported. These are rare; they are caused when an equipment failure occurs, such as a broken pipe or defective pumping station.
Here’s a look at what the Massachusetts law will require:
Immediate reporting: Sewer plants will be required to publicly report sewer overflows within 2 hours of discovery, with updates every 2 hours, and a report when the overflow ends. This final report will include an estimate of how much volume was released. These reports will be disseminated through the sewer plant’s website, emailed to officials in downriver communities and to residents who sign up to receive the emails, and to the largest local news outlets.
MRWC recommended two additional measures that we felt would improve the effectiveness of the alert system – requiring sewer plants to provide up-to-date and accurate reports on how much volume was released, and requiring that alerts also be posted on social media. Both of our recommendations were acknowledged as valid, but not incorporated into the regulations as they were seen as not viable.
Regular reporting: Sewer plants will be required to provide more detailed monthly reports to the state on sewer discharges, and the state in turn will publish annual reports for the public to review. Plants must also provide more information on sewer releases on their websites.
Environmental Justice issues: From the start, DEP placed an emphasis on how to effectively reach EJ communities – places where there are significant populations of low income, minority, and/or non-English speaking populations. In the Merrimack valley, the largest EJ communities are in Haverhill, Lawrence, Lowell, and Methuen. The law requires that warnings be posted at riverfront access points in languages that are predominant in the EJ area, and that they be sent to media that serves the EJ community.
Boards of health: Municipal boards of health and their health departments will be required to assume a new role in helping spread the word about sewer discharges. In the past, they haven’t been required to play any role. Boards of health will be required to post information and warnings at known public access points, such as boat ramps and swimming beaches. They may also use public alert systems, such as Reverse 911, to contact the public if a particularly large release occurs.
In the Merrimack valley, this new requirement will be placed upon the boards of health in Amesbury, Andover, Dracut, Groveland, Haverhill, Lawrence, Lowell, Merrimac, Methuen, Newburyport, North Andover, Salisbury, Tewksbury, and West Newbury.

What is really changing?
The plants in Lowell, greater Lawrence and Haverhill have been very responsive to the public outcry over CSOs, and on their own initiative they have greatly improved their public reporting of CSO events. Many of the new law’s requirements are already in practice at these 3 plants.
The biggest change that MRWC anticipates is due to the “blended/partly treated” reporting requirements. MRWC expects that the public will see at least twice as many alerts issued, because these partial treatment incidents are not currently being reported.
There are also some new elements that will add more data to what’s being reported to the public – for instance, estimating volumes soon after the discharge ends. Also, the requirements for boards of health is a new layer of public reporting.
As noted above, the law doesn’t require that alerts be posted on social media. MRWC has been posting its own alerts on social media for 4 years, and we’ve found it to be a very effective way to alert the public. MRWC will continue to issue its own alerts when sewage is released into the Mighty Merrimack.