A 40-million-gallon sewage spill that fouled the Merrimack River and closed North Shore beaches over the Fourth of July weekend has become a campaign flashpoint in the U.S. Senate race between Sen. Ed Markey and Rep. Seth Moulton. In the Massachusetts 6th Congressional District primary, Andover's Dan Koh launched his first television ad, and Republican Anne Brensley announced a write-in bid for secretary of state.

The spill matters locally: Andover has more than five miles of Merrimack River shoreline, and the town issued a separate advisory on Tuesday, July 7, warning residents to avoid the river after a combined sewer overflow from the Lowell Wastewater Treatment Facility.

A 42-inch force main at Haverhill's wastewater treatment center broke in two places on or around Friday, June 26, according to the Andover Townsman. Haverhill Mayor Melinda Barrett said a torrential rainstorm caused the rupture, which discharged roughly 8 million gallons of raw sewage per day until repairs were completed.

Moulton and Rep. Lori Trahan sent a letter to EPA Administrator Lee Zeldin calling for more federal funding to upgrade aging water and sewer systems. Moulton's office also announced he had secured an additional $10 million for Haverhill in a reauthorization of the federal Water Resources Development Act that cleared a key House committee. That would boost the city's allocation from $40 million to $50 million for upgrades to combined sewer overflows, systems where stormwater and sewage share pipes.

Less than a day later, Markey fired back with his own press release, touting provisions he and Sen. Elizabeth Warren secured in the Senate's version of the infrastructure bill to boost Army Corps of Engineers funding for Haverhill wastewater improvements. Markey also filed new legislation with Warren and Trahan that would create a $50 million emergency grant program for cities responding to sewer failures. Moulton was not a co-sponsor.

The Townsman noted that despite the jockeying, no new federal money has actually reached the region. The infrastructure bill still faces a long path in Congress amid partisan disputes.

Dan Koh, a former deputy Cabinet secretary in the Biden White House, launched his first television and digital ad campaign the week of Monday, July 14. In the spot, Koh says: "I've spent my career taking on tough fights. Trump's targeting anyone who gets in his way. But bullies only win when we don't fight back."

Koh's campaign has raised more than $4.5 million since entering the race, according to filings with the Massachusetts Office of Campaign and Political Finance, including more than $1 million in the second quarter alone. The campaign reported more than 12,000 contributions with a median donation of $15 and said it has not accepted corporate PAC money.

Koh is one of six Democrats competing for the MA-6 nomination to replace Moulton, who left the seat to challenge Markey. The only other Democrat running TV ads so far is Lynnfield businessman John Beccia.

Wayland Republican Anne Brensley announced Friday, July 17, that she is launching a write-in campaign for Massachusetts secretary of state after a state panel knocked her off the Tuesday, September 1, GOP primary ballot, ruling she fell short of the required number of signatures.

Brensley's campaign alleged it was duped by a fraudulent signature-gathering operation that also removed Anne Manning-Martin, the GOP lieutenant governor candidate from Peabody, from the ballot. Brensley had won 57% of the delegate vote at the Republican convention earlier in 2026.

Massachusetts Republican Party Chairwoman Amy Carnevale said in a statement that the party will assist Brensley in reaching the 5,000 write-in votes she needs to reach the November ballot. If she clears that threshold, she would face incumbent Democratic Secretary of State Bill Galvin, the country's longest-serving election official.

The September 1 primary is the next milestone for both the MA-6 congressional race and Brensley's write-in effort. Six Democrats will appear on the MA-6 ballot.