History and ecology intersect in Mill Brook study

Watershed analysis finds parts of stream intolerably warm for fish, dams thought to factor heavily.

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West Tisbury continues to assess how best to preserve Mill Brook, the stream that creates Mill Pond, and how to best manage the 2,928-acre watershed that feeds Mill Brook.

The Mill Brook watershed management planning committee recently concluded parts of Mill Brook, including Mill Pond, become fatally hot for some species of fish in the summertime. As The Times reported in December, some ponds heated to above 80°F in the peak of summer. Because of weir board dams at various points in the brook, these fish aren’t able to swim to cooler spots upstream, the committee reported. Weir board dams help create the Mill Pond and several other ponds along the brook. The committee recommended asking “willing” landowners to remove weir boards and other damming material to facilitate fish movement. As several audience members pointed out at a June 25 presentation of the committee’s report in the West Tisbury library, undamming the brook would also open the waterway to anadromous fish like alewives.

While embraced by many at the presentation as a productive step, draining the ponds, frequently referred to as impoundments in the committee’s report, struck an unpleasant chord with at least one committee member.

“We did not address in this report at all any of the multitude and myriad of other uses that those bodies of water bring to people as far as recreational, as far as historical, as far as aesthetic,” committee member Selena Roman said. Roman owns part of a pond fed by Mill Brook.

She later told The Times the committee had originally talked about those factors along with private property rights, but due to limitations in the funding “those elements all fell outside of that RFP.”

Roman said Albert’s Pond, the one she has a stake in, supports a thriving ecosystem, and she would like to see it preserved. Perch, trout, and bass are found in the water there, she said. From her home overlooking the pond, she and her family have watched osprey, otters, and other animals prey on those fish. Yes, otters. The Vineyard’s river otter population is “very robust,” according to Sheriff’s Meadow Foundation executive director Adam Moore. Roman also said deer, kingfishers, herons, bitterns, and snapping turtles are a regular sights at Albert’s Pond.

According to information provided to her from the Littlefield family, folks she said previously owned the pond real estate since the early 19th century, the pond dates to about 1850.

She said she could not see value in eliminating the pond. She also noted other factors that may tax the watershed weren’t in the scope of the report. “This report didn’t even touch groundwater and groundwater withdrawals,” she added.

Dredging Mill Pond has been debated in West Tisbury for several years as a way to mitigate water temperatures. However, Kent Healy, an engineer and West Tisbury selectman, said after the presentation that dredging the pond runs the risk of damaging water flow. Healy has studied the watershed extensively, and consulted on the committee’s report. He said Mill Brook water passes over delicate geology. Digging into it with a dredge could puncture the strata, drain the pond, and possibly send the brook underground, he said.

The report offered a third alternative to dam-busting or dredging — creating a new pond.

“Within the 2½ acres of existing Mill Pond,” the report states, “investigate the concept of a pond separate from, but co-located with, a free-flowing Mill Brook. This would require qualified engineering and environmental assessment. This concept could maintain recreational and aesthetic purposes at Mill Pond dam, while reducing solar heating and restoring the ecology of the stream in this location.”

Among several other recommendations, the committee also advocated for taking steps to acquire parcels of land in sensitive areas of the watershed, and it saw value in finding alternatives to withdrawals and diversions along the brook. Water is channeled from the brook for fire suppression and agricultural purposes, among other reasons.

Mill Brook water forms an artificial pond behind the old mill building on Edgartown–West Tisbury Road colloquially known as “Fire Hydrant Pond,” Fire Chief Manuel Estrella III said.

He described the pond as “very important.” The pond connects with a dry hydrant in front of the Council on Aging on State Road near Alley’s, and provides firefighting water for that portion of town, he said.

The Whiting diversion dam near the Scotchman’s Bridge Lane bridge was one of the diversions highlighted in the report. It “directs as much as 20 percent of the flow away from the main channel of Mill Brook,” the report states.

“My great-grandfather dug that,” West Tisbury town clerk and conservation committee chairman Tara Whiting told The Times. The diverted water flows to Parsonage Pond on land Whiting’s family sold in 2013. The pond once provided water for a lot of livestock, Whiting said. It’s been a few years since a Whiting has been out to the dam to assess its condition, she said, and noted the dam itself is not on property her family owns.

“I very much appreciate the amazing work of this body,” George Gay, a property owner along the brook, said at the presentation. “I mean, the fact that a public entity met as volunteers on 70 different occasions over the course of four years just blows you away.”

The audience broke into applause.

“I offer a particular thank-you to Prudy Burt, who engaged me and my family over the course of many years,” he said.

Gay went on to say his “bigtime wish” was to see “herring” or another breed of “anadromous fish” running up the brook by his house. He urged the town to work toward that goal.

At their regularly scheduled meeting last week, West Tisbury selectmen unanimously voted to accept the report.

Selectmen chairman Cynthia Mitchell, who co-chaired the Mill Brook watershed management planning committee, told The Times she expects the West Tisbury conservation commission, in conjunction with Island environmental groups like The Trustees of Reservations and the Vineyard Conservation Society, to take leadership in developing the recommendations outlined in the report. Mitchell also expects the selectmen’s office to collaborate on the work.

At some point, Mitchell said, she envisioned Chilmark entering the process, as a portion of the Mill Brook watershed, including the headwaters of the brook, are in Chilmark.

Since her co-chair on the committee was Chuck Hodgkinson, administrator for the Chilmark conservation commission, she said, the town already has an informed person on hand.

Overall, Mitchell said she was pleased with what the committee concluded. “My personal opinion is that the recommendations of the committee are good ones,” she said.