The eight-year-and-counting project to keep White Park’s pond from being filled with lotus plants has returned in the shape of floating, paddlewheel-driven powered rakes.
Two of these Hydro-Rakes from Solitude Lake Management in Shrewsbury, Mass., were on the pond Wednesday, part of a multi-day effort to pull up approximately 1,200 cubic yards of sediment and vegetation, which will be piled on the ground to drain before being taken off site for disposal.
The one-person boats are propelled by two paddlewheels, one on each side, with a large hydraulic rake up front to gather and carry material.
The work will slow the spread of the invasive plant, which first showed up here in 2018, including removing plants from, at or near the surface that would interfere with ice-skating when the pond freezes. But officials know this by itself won’t eliminate the problem.
The best way to get rid of a fast-spreading aquatic plant like the lotus would be to drain the pond and dredge out the entire bottom to remove any roots and seeds. Hydro-raking is a short-term solution while a longer term plan, including funding, is developed.
Even dredging, however, isn’t perfect. On its website about the project, the city acknowledges that the expensive and disruptive process can’t guarantee complete success: “This is where a pond maintenance plan comes into play” to ensure that any re-emergence is nipped in the bud, says the site.
The City Manager’s budget request for the 2027 fiscal year includes $200,000 for the pond project, pending City Council approval.
Two species of lotus are native to Central America and parts of the southern U.S. They are relatively new to New England and considered invasive here because of their propensity to spread quickly and dominate water bodies.
“Controlling the spread of lotus is not only necessary for the ecological health of native species and habitats within White Park Pond but is also an urgent concern for potential spread to other water bodies in New Hampshire and throughout New England,” wrote David Gill, Park and Recreation director, in a July report to the City Council.
A single flower of the lotus was first seen on the pond in 2018 and within three years the plant covered more than half the surface of the pond, which is a little less than two acres. The pond is less than 4 feet deep. Less than a foot of sediment lies under the water in all but the northwest corner, which was not dredged during work in the 1980s; in that portion, the sediment is up to 5 feet deep.
As for the cause of the aquatic weed invasion, it’s almost certainly the same cause that brings in invasive species: People.
“Although we do not know for sure we assume the Lotus plant, like the Koi fish in the pond, was placed there by someone,” Gill says in the report.
