Flooding and stormwater

Updated September 21, 2026

What's happening

On July 9 the City Council voted 10-0 to borrow $130,392,395 for the Morrison Avenue project — a giant underground box culvert meant to stop the chronic flooding around Morrison Ave in greater Davis Square (digest). It is the single largest borrowing the city has authorized for a flood project, and the money is already built into approved water and sewer rates. The design account got a top-up on September 10, when the Council approved a $315,000 transfer from the sewer enterprise debt-service account to the Morrison Avenue and Greater Davis Square sewer-separation design fund, recommended 5-0 by Finance on September 3; Infrastructure Finance Director Michael Richards said paying the short-term borrowing now keeps it from rolling into long-term debt (Sept. 3 digest; Sept. 10 digest). The same package accepted a $187,200 state Municipal Vulnerability Preparedness grant for the Public Space and Urban Forestry Division to plant canopy on narrow, hard-to-plant sidewalks, matched only with staff time. The city's September 17 announcement adds a $25,400 city match, a 14.6% tree canopy, and a finding that over 80% of the city is a heat hot spot; RFP 27-14, the "Green and Cool Somerville" design contract for about 100 planting sites with documents due by June 30, 2027, was released September 9 and its deadline extended to September 30 at 3 p.m. (bid page).

The other half of the flooding story is a fee that still doesn't exist. A stormwater fee — charging property owners by impervious surface, which would shift cost onto big parking lots — has been promised for years and slipped again. Raiche told the Council on April 23 it wouldn't be ready for July 1; on June 11 he said he'd be "angry and embarrassed" if it isn't ready by January 2027. The FY27 budget book records the goal as flatly "Incomplete. Delayed as the Department continues to reconcile account mismatches."

The story

Morrison Avenue

The project rebuilds drainage and sewer under Morrison Ave from Cedar Street to Grove Street plus the surrounding blocks, with related work on Jay Street and Powder House Boulevard. Infrastructure Director Rich Raiche's numbers: in a 10-year storm it cuts flooding from about 1.33 million gallons to 170,000 gallons, cuts combined sewer overflow volume by roughly 24 percent, and replaces a sewer pipe under the community path that "is going to fail" and already failed once in 2017. Ward 5 Councilor Naima Sait, who lives in the affected area, described basements on those streets filling with sewer water.

The mid-summer timing was a state deadline. Somerville applied last year to the Clean Water State Revolving Fund on a $130 million estimate and the paperwork was due July 15. The terms are why the Council moved fast: 2 percent over 30 years against roughly 4.3 percent commercially, plus likely partial loan forgiveness because Somerville qualifies as a disadvantaged community. Raiche warned the program runs on a Biden-era appropriation that "Trump has cut," so losing the slot would mean losing the terms.

Design is at 60 percent and the estimate has already come down to $111 million; Raiche expects to return in December to rescind whatever savings hold. Construction starts summer 2027 and runs about four years. The project page notes streetscape work has been cut back to roadway and sidewalk restoration "to ensure full, timely delivery of essential sewer and stormwater management improvements" — the flood infrastructure survived the budget squeeze; the nicer street did not.

One oddity worth a call: the FY27 budget book lists "Continue the Morrison Avenue Storage & Sewer Separation project design" among the Infrastructure Department's sewer-modernization goals, immediately followed by a bare parenthetical, "(This is effectively shelved until the economy rebounds)" (budget book, p. 180) — submitted June 4, five weeks before the Council authorized $130 million for it.

On August 27 the Council referred item 26-1226, a $315,000 transfer from the Sewer Enterprise Debt Service Account to the Morrison Avenue and Greater Davis Square Area Sewer Separation Design Capital Fund, to the Finance Committee, which meets September 3.

The stormwater fee

Somerville bills stormwater through water and sewer usage, which means a house with a small roof pays and a supermarket parking lot largely doesn't. A stormwater enterprise fund charging by impervious surface would change that. Ward 2 Councilor JT Scott has pushed it for years — he named Target's lot on April 23 — and the answer keeps being the billing database. Both the water and sewer enterprise sections of the FY27 budget book carry the same FY26 goal, "Design and implement a new billing system for a stormwater enterprise fund," marked incomplete.

Scott used the June 11 rate vote to skewer the study trail, citing a $90,000 water-affordability report and another that recommended the city "diversify revenue sources, formulate new policies and practices, and enhance communication" — "I think we're really getting our money's worth with these consultants." Raiche said the work is now being done in-house, and that the January version would include incentives for on-site retention.

The rest of the pipe program

Mystic River Outfall and Foss area separation. Ninety-five acres of separation in Winter Hill and Ten Hills, which Raiche called a "three-fer" — CSO reduction, flood relief near Foss Park, infrastructure renewal — got a Stantec design contract extension to September 5, 2028 at the June 16 Finance Committee. The city's buying plan schedules a $65 million construction procurement for December 2026, alongside a $50 million Morrison Ave procurement.

Spring Hill. The Spring Hill sewer separation along eastern Highland Avenue is finished; the Council approved a three-month, no-cost Stantec extension in January just to get the as-built drawings done. The Highland Avenue redesign — protected bike lanes, bus improvements, Cutter Avenue to Hamlet Street — follows that underground work. Spring Hill is also a caution about green infrastructure: when Hardt asked why the city isn't building more stormwater bump-outs, Raiche said they depend on subsurface sewer work and utility conflicts, and Spring Hill yielded only about 11 of 60 potential sites.

August 27. The Council approved $1,000 inter-fund transfers seeding capital accounts for the Union Square sewer bond (26-1223), Spring Hill design (26-1224) and the Poplar Street Pump Station design (26-1225). It also referred item 26-1255 to Finance: a $187,200 Municipal Vulnerability Preparedness grant from the Executive Office of Energy and Environmental Affairs, no new local match, to Public Space and Urban Forestry for a "Green and Cool Somerville: Sustainable Sidewalk and Trees" project.

The framing to keep in mind: Raiche told the Council in April that stormwater, not CSOs, is the largest source of bacterial pollution in both the Alewife and the Mystic, and the city's own CSO page says that with all sources counted, Alewife Brook meets water quality standards only 45 percent of the time in a typical year. The expensive sewage plan and the still-unbuilt stormwater fee are aimed at the same river.

What's next

October 30, 2026 — comment deadline on the draft CSO plan, extended a month from September 30, with a third public hearing added October 28 at Somerville City Hall; the plan sets the terms for the separation work. See combined sewer overflows.
November 1, 2026 — under the new charter the mayor must submit an updated capital investment plan, the first refresh in roughly four years. See the capital plan.
December 2026 — Raiche returns to Council to rescind unused Morrison Ave borrowing; the $50M Morrison and $65M Mystic Outfall construction procurements go out, with bids over the winter.
January 2027 — Raiche's stated deadline for the stormwater fee, with on-site retention incentives. Whether it appears is the test of a promise now years old.
Summer 2027 — Morrison Ave groundbreaking, about four years of construction.