Stony Brook Restoration Plans Being Finalized

BREWSTER – Though not nearly as ancient as the fish who use the passage each year, the stones and fish weirs lining Stony Brook have been in place for many decades, and some are beginning to show signs of trouble. To that end, the town is finalizing an ambitious plan to rebuild parts of the fish ladder and surrounding walls.

“Everything’s about the herring, and everything’s about the history of the site,” Natural Resources Director Chris Miller said last week in a public presentation about the project. The work, expected to take place this winter, involves several components; construction is expected to cost around $917,000, with the bulk of the funding coming from the federal Natural Resource Conservation Service.

A key problem is the stone wall that separates the mill’s elevated headrace pond from the main brook, along which runs a footpath.

“This path has begun to sag,” Miller said. Town officials have a theory. “The water in this upper pool is actually flowing through the wall. With freeze-thaw, in time, it’s starting to push out some of the lower stones,” he said. The project calls for parts of that wall to be repaired or rebuilt, with a liner to be installed along much of the wall of the headrace pond. “That should help us with the freeze-thaw cycles and the sediment moving, because we’ll have less water flowing through the wall,” Miller said.

Also on the south side of the road, the contractor will rebuild a portion of the stone wall on the edge of the main pool, where a stormwater drain has begun to fail. Here, crews will likely install low concrete footing to stabilize the bank, with stones on top.

“Our goal is to have as little concrete exposed as possible and to reuse the stones where we can,” he said. Throughout the project, the original stones will be reused as much as possible; some of them were part of long-gone mills and structures from centuries ago. In the 1860s, the area was known as Factory Village and was a center of industrial activity.

In other locations, work will be done on the aging fish weirs, the partial walls that act like steps in a staircase to help spawning herring reach the inland ponds. Some of the concrete weirs have been in place since at least the 1940s. In some cases, the steps are too steep for the fish to navigate easily. River herring and alewives use a great deal of their stored energy climbing to their spawning ponds, and easing their passage is a key natural resources strategy for helping the species remain strong.

“They’re not salmon. They’re not leaping out of the water up over these falls,” Miller said. In some spots, additional weirs will be added to make the steps easier for fish to navigate. The work will likely require parts of the waterway to be drained, and a pipe will likely be needed to briefly divert part of the flow, though fish will be swimming downstream at that time and will be unencumbered by the pipe, he said.

The project has been a partnership of town staff and committees and the Cape Cod Conservation District, which funded much of the design work, with support from engineers Tighe and Bond and the Massachusetts Division of Marine Fisheries. The Natural Resources Conservation Service is providing 75 percent of the anticipated construction costs, with the town paying the remainder; voters have already approved a $125,000 Community Preservation Act grant and a $200,000 appropriation for that purpose.

Miller said the project next goes before the conservation commission on April 23, with the remaining permitting to be completed this spring. Bids will be solicited around August, with construction expected to begin sometime around November, to be completed well before the return of the fish in the spring of 2025.

Meanwhile, this year’s herring have arrived but are being thwarted by high water levels in the ponds caused by recent heavy rainstorms. Miller said the alewife and mill sites committees have been actively managing the water levels.

“On an almost daily basis they’re out there working on the water control to make sure that there’s no issues,” he said. Last week, town officials found that an obstruction had slowed the flow of water between Upper and Lower Mill Pond. “So when we got that blockage out, the water level rose almost four inches and we had to quickly flush extra water through the dam,” he said. Herring are currently running but will have to wait several days for the water level to drop and the flow of water in the stream to slow down. Nearby residents have observed that the water level in the ponds is much higher than normal, but Miller said the town needs to lower the level slowly.

“We have fish in the stream,” he said. “We can’t wash them all back out to sea.”

Brewster now has an electronic fish counter on the south side of the street to track fish when they make it to the big pond. Volunteers also provide a visual count for 10-minute periods. The recent high water mark for the herring run is 271,000 fish in 2014, but the average is around 86,000 with fairly wide year-to-year swings. Once the fish make it past the mill site into Lower and Upper Mill Ponds and Walkers Pond, they have 386 acres of spawning habitat. If the water levels are high enough, the herring can make it to Slough and Elbow ponds.

Rich Eldred contributed to this story.

Learn more at https://www.brewster-ma.gov/stony-brook-mill-site-retaining-wall-and-fish-passage