AMESBURY — Don't expect the problems affecting Lake Attitash to wash away now that the Municipal Council has approved spending $45,000 to treat the body of water that runs between Amesbury and Merrimac.
The two problems plaguing the lake — an invasive weed known as milfoil and blue-green algae — will continue to exist, but Lake Attitash Association leaders say the funding will allow them to be better equipped to deal with the issues.
"I can't say we're all done. We'll be fundraising and asking residents every year to maintain and improve the water quality of Lake Attitash," Cindy Roberts of the Lake Attitash Association said.
Last week, the Municipal Council voted to approve giving $45,000 from the free cash account to the lake association, which has been working over the past year to raise $100,000.
The group is trying to tackle long-standing problems with milfoil and blue-green algae, which have worsened in recent years.
High levels of blue-green algae forced the lake to be closed for periods over the past two years — for 10 weeks in 2010 and from mid-June to early July last year.
The two-pronged treatment approach will involve attacking the milfoil first. The Lake Attitash Association will develop a strategy to go after the blue-green algae, which is actually a bacteria known as cyanobacteria.
The association is waiting on the results of a federal Environmental Protection Agency study on the lake. Lake Attitash was one of a handful of lakes picked by the EPA for the study on New England lakes.
The EPA study will try to determine what causes the algae blooms: Is is coming into the lake from an outside source, such as storm drains, or is it already in the lake's sediment?
If the study finds the algae blooms are caused by runoff, the group has to figure out a way to stop it, Roberts said.
Additionally, if the study finds the bacteria "already in sediment from Sargent Farm or past use of fertilizer," they'll have to figure out a way to treat it, she added.
Up until February 2011, Sargent Farm in Merrimac processed gelatinous waste from Kraft Food. The association worried that phosphorus and nitrogen, two by-products of the composting, were entering Lake Attitash as a result of run-off from the processing of the material.
Along with identifying the source of the algae blooms, the EPA will recommend a plan for the association.
Of the two problems facing the lake, the milfoil will be the most expensive to treat.
Roberts said it will cost approximately $80,000 to treat the milfoil with fluridone, a herbicide that is applied in pellet form.
The fluridone is slow-acting and needs to be in contact with the milfoil for 60 to 90 days. Aquatic Control Technology, the company working with the association, recommends two to three applications over the 60- to 90-day period.
The remaining $20,000 of the association's $100,000 fundraising campaign is budgeted for the algae. The herbicide copper sulfate is being proposed to treat the bacteria, but that plan may change based on the findings by the EPA, according to the association.
While both herbicides are approved by the EPA and the state Department of Environmental Protection for use in drinking water supplies, Amesbury Public Works director Robert Desmarais asked the Conservation Commission last year to create a set of guidelines if it approves the treatment plan.
Some of the recommendations include notifying officials a certain number of days prior to the treatment so that the lake can be drawn down in advance. Also, Birches Dam will be closed for at least a month after the treatment is applied.
In the summer of 2013, the association will begin a monitoring program so people can keep an eye out for milfoil. The group plans to buy large tarps to be placed on the bottom of the lake over areas where milfoil is spotted to deprive it of sunlight and kill it.
"We'll be vigilant to make sure it doesn't get out of control," Roberts said.