Scientist backs plan for using herbicide to kill invasive weeds in Stockbridge Bowl
STOCKBRIDGE — The debate over how to weed out invasive plants that are strangling parts of Stockbridge Bowl remains unsettled.
An hourslong, often tense public hearing on the issue earlier this week was continued to Jan. 22 after commission members heard a recommendation from a specialist in lake restoration. Robert Kortmann, a scientist hired by the commission, said the best first step to attack the Eurasian milfoil invasive plants is a limited one-season chemical treatment of the lake using fluridone, a commonly applied systemic herbicide approved by state and federal environment agencies.
Systemic herbicides are absorbed by roots or foliage and moved throughout the plant.
Kortmann, president of Ecosystem Consulting Service, Inc., in Coventry, Conn., was asked to weigh in on whether there were any downsides to the Stockbridge Bowl Association's notice of intent application to the Conservation Commission to use Solitude Lake Management to apply the herbicide this spring. As required by state regulations, the SBA, as applicant, is paying for his services.
At Tuesday's meeting, which was attended by more than 75 people, highly skeptical commission members who have long opposed chemical applications on the state-owned lake cross-examined Kortmann after he told them that "fluridone treatment should be part of a lake milfoil management plan."
Kortmann previously studied the toxic cyanobacteria bloom in late August and early September that placed the lake off-limits for recreation because of a potential health hazard and forced the watercraft segment of the annual Josh Billings RunAground triathlon to relocate
at Richmond Pond.
He attributed the outbreak to a "wind mix-down" of water layers below the lake's surface caused by intense rainstorms and hot weather that fueled development through photosynthesis of toxic algae, a phenomenon that was common to many other lakes in the Northeast region last summer.
Kortmann called Solitude's plan for fluridone treatment to combat weeds, the approach proposed by the SBA, "a very good one with the right elements in it."
He suggested eventual chemical treatment of the entire lake as long as it doesn't hinder calcite formation. Lack of calcite formation could alter the nutrient-removal mechanism of the lake and lead to changes in lake function that could result in higher risk of algae blooms, Kortmann explained.
"Milfoil does some pretty nasty things," he said. "It can become so dense and form a canopy that shades out more desirable vegetation. It's something you want to reduce significantly if not ultimately eradicate."
Kortmann recommended the monitored, limited chemical treatment for a 40-acre southern portion of the 372-acre lake this spring as a "dry run" for potential application of the entire Bowl in future years. A fluridone application to that part of the lake early in the growing season at the low-dose levels proposed by Solitude would be the best approach, he said, "and it addresses the unknowns."
Dr. Charles Kenny, who chairs the Board of Health, asked Kortmann whether there's something unique and unknown about Stockbridge Bowl that contributed to last summer's toxic algae outbreak.
Kortmann replied that the lake "already has demonstrated vulnerability to harmful cyanobacteria blooms. It still is vulnerable to those blooms, whether or not treated by fluridone." He said his proposed, limited "large block" treatment of the lake would demonstrate whether there's any potential impact on future algae outbreaks.
"I'm not opposed to a whole-lake treatment," Kortmann added. "I'm opposed to a whole-lake treatment without knowing that there isn't going to be an impact on calcite formation."
Responding to Kenny's suggestion that the chemical treatment could be postponed for a year in order to further research the causes of last summer's algae outbreak and any potential risk of a fluridone application, Kortmann said he doubted a delay would reveal how vulnerable the lake might be to another toxic algae bloom on the surface.
Only a regular lake monitoring program would provide potential answers, he added.
Kenny then asked, "Should we study the lake first and then decide how to do the fluridone?"
"The lake is vulnerable to the cyanobacteria bloom," Kortmann replied. "I see that as more or less separate from the fluridone treatment."
He said it's up to the Conservation Commission to decide on whether to postpone a treatment in order to prioritize further studies.
"The only way to determine whether a whole-lake application of fluridone might have an impact is to examine a significant block [partial] treatment with monitoring in year one to get the answer to whether a whole-lake treatment in year two would be a problem," Kortmann said.
Commission member Patrick White said the board's mission is to minimize the risk that "we could add to the cyanobacteria problem," which he and other members described as a greater threat to the lake than the milfoil weed "nuisance."
Regular health checkups are essential, Kortmann said, to track temperature, oxygen and nutrient levels in the lake. But the fluridone treatment can take place despite a lack of previous lake monitoring, he added.
Responding to a query from Conservation Commission member John Hart, Kortmann said a drawdown of the lake would not be an effective method of controlling milfoil weeds, unless it went extremely deep, to at least 8 or 9 feet.
Long-term management plan
A second expert witness at the hearing, Emily Stockman, a professional wetlands and soil scientist and consultant who owns Stockman Associates in Adams, was asked by the Conservation Commission to "peer review" the Bowl Association's application for chemical treatment of the lake, based on the state's Wetlands Act regulations.
She acknowledged the application's goal of controlling Eurasian milfoil weeds as "well-intentioned" but described it as "very broad and general." Stockman maintained that only a long-term management plan can succeed as an ecological restoration project for the lake. She asserted that the SBA and Solitude have not submitted sufficient details of a future, well-defined plan for monitoring and next steps.
"The regulations, in my opinion, don't allow the luxury of putting blinders on and looking at just the milfoil," Stockman said.
In a comment following Tuesday's meeting, Richard Seltzer, president of the Stockbridge Bowl Association, expressed appreciation "for Dr. Kortmann's unstinting praise for the SBA's Notice of Intent and his support of the use of the requested herbicide fluridone to control milfoil."
And in an email on Friday, Seltzer wrote that, "In light of the recent testimony from the Conservation Commission's own expert endorsing the use of fluridone to control milfoil in Stockbridge Bowl, I advised Sally Underwood-Miller, secretary to the Commission, that I think it is in the best interests of all to amicably settle the herbicide dispute. After sending an e-mail invitation to talk two days ago and a voicemail message today, I am disappointed to report that I have gotten no response from Ms. Underwood-Miller."
The Berkshire County League of Sportsmen has urged the Conservation Commission to oppose a chemical treatment of the lake because of what it views as risks to fish and other aquatic wildlife, according to a letter from Wayne McLain, the organization president, read by Ron Brouker, the commission chairman, during last Tuesday's meeting.
However, the state Division of Fisheries and Wildlife's Natural Heritage and Endangered Species Program supports the proposed fluridone treatment for this year, asserting it would not threaten rare snails and other aquatic wildlife that inhabit the lake, followed by monitoring and a management plan subject to state review prior to additional chemical applications.
The state Department of Environmental Protection allows a short-term herbicide treatment followed by long-term management plan, said Elisabeth Goodman, attorney for the Stockbridge Bowl Association.
Near the conclusion of Tuesday's meeting, the Conservation Commission approved a motion by member Sally Underwood-Miller asking the Stockbridge Bowl Association to submit a revised application by Jan. 22 with additional details specifying lake restoration goals and monitoring of the treatment plan's success.
Goodman declined initially, requesting an up or down vote on the notice of intent submitted. Underwood-Miller said the notice is insufficient for the commission to make a decision.
On the advice of Rebekah Lacey of town counsel Miyares & Harrington, and with Goodman's agreement, the commission voted to resume the public hearing at 7 p.m. Jan. 22 with additional information to be submitted by the Bowl Association.
Kortmann told The Eagle in an email on Thursday that "I would not recommend a treatment of the lake's entire plant community before determining that problems would not result."
If his recommended "large block treatment" of the 40-acre southern portion of the lake does not cause problems, he added, "I wouldn't be opposed to a whole-lake treatment."
Clarence Fanto can be reached at email@example.com, on Twitter @BE_cfanto or at 413-637-2551.
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