Most people who walk the loop at Horn Pond every spring assume the herring figured themselves out back in 2018, when a rip-rap bypass channel reopened Scalley Dam after nearly a century without a working fish passage. That assumption held for a while. Then in 2025, out of roughly 815,000 river herring that swam up the Mystic River and passed the Mystic Lakes Dam, only about 6,900 made it the rest of the way up the spillway into Horn Pond itself.
That gap, reported by the Mystic River Watershed Association, is the reason nearly everything currently under construction, staffed by volunteers, or budgeted around the pond this year is happening at all.
The math that got worse, not better
When the original bypass opened at Scalley Dam in 2018, it returned about 25,000 herring to Horn Pond in its first season, a real milestone after so long without passage. Three years later the count peaked near 42,000. Then it slid. In the years that followed it dropped back under 20,000, and by 2025 it had fallen to 6,900 fish out of roughly 815,000 that reached the Mystic Lakes Dam upstream, according to Middlesex East reporting on the project.
| Year | Herring counted entering Horn Pond |
|---|---|
| 2018 (bypass opens) | about 25,000 |
| Peak, roughly 2021 | about 42,000 |
| Following years | below 20,000 |
| 2025 | 6,900, out of about 815,000 at the Mystic Lakes Dam |
Less than one percent of the run that reaches the dam actually makes the final push into the pond. That bottleneck, not a shortage of fish in the ocean, is why the city and the Mystic River Watershed Association spent years designing a permanent pool-and-weir passage instead of patching the old bypass again.
Why 2026 counts as "before"
The Horn Pond Fish Passage received the last of its construction funding this spring, pulled together from a settlement tied to the Industri-Plex Natural Resource Damages Trustee Council, a North American Wetlands Conservation Act grant, and a $1 million gift routed through the watershed association from an anonymous foundation. Construction is expected to start by fall 2026, timed to finish before the herring return in spring 2027. The new design replaces the rip-rap channel with a pool-and-weir system, adds an ADA-accessible path to an underwater viewing window at Scalley Dam, and puts up new educational signage.
That makes this year's monitoring season, which officially ran from April 12 through June 20, the last full count anyone takes before the passage itself changes. The watershed association has said as much directly, calling the 2026 estimate the project's final pre-construction baseline. Herring monitor Jim Joyce, co-founder of Friends of Horn Pond, put it this way after watching a season of counts:
"Seeing the pond teaming with the small fry herring later in the season tells me that our ecosystem is thriving."
Volunteers are also in year two of a five-year hand-pulling campaign against invasive water chestnut in the pond's lagoon, run jointly by Friends of Horn Pond, the watershed association, Paddle Boston, and the city's Conservation Commission. Year one, completed in June 2025, cleared about 15,000 pounds of the plant. Year two more than tripled that, with over 150 volunteers pulling more than 46,000 pounds across four days in late June, then another 21,000 pounds on a single Saturday in mid-July. Left alone, water chestnut can deoxygenate a pond and kill off the fish a new passage is built to let in, so this year's scaled-up removal is effectively clearing the way for the same project going in at the dam.
The parking lot is the tell
The city isn't only fixing the water side. It's expanding the Lake Avenue lot by more than 30 spaces, adding handicap parking, new sidewalks, and ADA ramps, continuing work that started in fall 2025. The same project adds a rain garden built from curb cuts, a sediment forebay, and a biofiltration basin, engineered to keep runoff from all those additional cars out of the pond itself.
Mayor Michael Concannon connected the parking work directly to what's coming at the dam:
"It's gratifying to see the community fully embrace our natural gem Horn Pond."
A city does not typically budget for 30 new spaces, ADA infrastructure, and stormwater filtration at a park that already has enough room. This is anticipatory spending. The people managing Horn Pond expect meaningfully more visitors once the underwater viewing window and signage go in at Scalley Dam, and they're building the lot for that crowd now, before it arrives.
What still works exactly like it always has
None of this changes what the pond offers on an ordinary Tuesday in August. The basics that Woburn residents already rely on are still exactly where they've always been:
- A paved 2.2-mile loop trail around the pond, flat enough for jogging, biking, or a stroller, with wooded side trails for anyone who wants a longer walk.
- Two city-run boat ramps: a concrete ramp off Lake Avenue on the south shore with room for about 10 trailers and 50 cars, and a second paved ramp at Beacon and Sturgis streets in Ice House Park on the north shore, with tighter parking there and additional access at Clapp Park on Arlington Road.
- Seasonal kayak rentals through Woburn Recreation's partnership with Coast to Coast Paddle, with a single kayak running $20 for the first hour up to $70 for a full day. A separate limited-run program called Boating in Boston has also rented kayaks from the main lot on select summer weekends at a lower hourly rate.
- Trout stocked every spring and fall, with the best bass fishing on summer evenings and yellow perch keeping anglers busy even through the winter.
Where the loop ends
For anyone who finishes a walk around the pond and wants dinner nearby, downtown Woburn has added two spots this year. The Vig Kitchen & Bar opened on Main Street in March, serving classic cocktails alongside apps, burgers, mussels, and pizza. A few doors down, The Down Low, a retro cocktail bar tucked into the basement of the Brickyard pizzeria, has been open since January. The Brickyard itself is running a Summer '26 outdoor series this year, with concerts on the patio Wednesday nights and acoustic sets Friday nights through the season, so a loop around Horn Pond on the right evening can end with live music a short drive away.
What this year actually is
2026 is not a routine maintenance year at Horn Pond. It's the transition year. The baseline herring count closes on this season's data. The old bypass channel gets replaced with something built to hold a run in the hundreds of thousands instead of the thousands. The parking lot that's been adequate for decades is being rebuilt for a bigger crowd before that crowd shows up. None of it changes what the pond offers today, the same loop, the same boat ramps, the same evening bass fishing, but it does mean the version of Horn Pond most Woburn residents know now will look different by the time herring return in the spring of 2027.
If you're weighing whether Woburn's slower, greener side fits your next move in Metro Boston, Neran Rohra is glad to talk through what living near a place like Horn Pond actually feels like day to day. Let's Connect.
