Make me warm all over
With a feeling that I'm gonna
Love you till the end of time.”
- Leon Pober
ORLEANS — The Orleans Pond Coalition may not be prepared to aerate Sarah's Pond “till the end of time,” but it's all in on backing a two-year demonstration project using “tiny bubbles” to restore the pond's health.
On Nov. 6, the conservation commission decided unanimously that the effort to employ “ultrafine bubble oxygenation” could move forward without a formal notice of intent, finding that the work was not likely to have a significant effect on wetlands. The commission asked that it receive regular progress reports.
Commission member Judith Bruce recused herself so she could represent the Orleans Pond Coalition along with its technical advisor, Dr. Kenneth Wagner, a scientist she said “has literally written the book on lake and pond management in Massachusetts. There hasn't been a lot of work looking at new technologies for fixing fresh water ponds, and the OPC wanted to see if we could add to that toolbox.”
Wagner, president of Water Resource Services and editor in chief of the peer-reviewed journal Lake and Reservoir Management, said Sarah's Pond, located off Davis Road, is like many Cape ponds that have been degraded over time. He compared fixing the pond to repairing a leaky boat: “You can patch it, but you won't get rid of the water that's already in there.” For water, read phosphorus, which in low-oxygen environments can encourage algae growth. “The nutrients are already in there,” he said. “We have to turn on the bilge pump and clean it out.”
Wagner reviewed the ways to do that. He called dredging “technically the best but economically and permit-wise the worst, and it's hard to get rid of (dredged) sediment.” He said alum treatment, such as recommended by the town's marine and fresh water quality committee for Uncle Harvey's Pond, is “reasonably successful” though there is a “risk of toxicity at the time of treatment.”
Water suppliers “use oxygenation all the time,” Wagner said. There are several methods; the one proposed for Sarah's Pond involves drawing water out of the lake, oxygenating it, and returning it with “very, very small bubbles” unlikely to disrupt the sediment. “We're giving (the pond) oxygen because it can't get enough from the atmosphere in the summer” he said.
There are reasons oxygenation isn't done often in recreational bodies, according to Wagner. “If you dredge, you're done,” he said. “Phosphorous deactivation (by alum treatment, for example) lasts for some years. If you oxygenate, you need to do it each summer. Over time the oxygen demand goes away, and you'll need less and less.”
Noting that he had recommended an oxygen treatment for a recent Nickerson State Park project, Wagner said the Commonwealth said it couldn't “guarantee they'd have the money in the budget every year.” The park pond got an alum treatment.
The difference in Orleans, he said, is that the OPC has made a commitment to support the two-year experiment. A fact sheet says the Coalition “is experiencing upfront consulting costs of $10K which will be higher than they will be for subsequent applications, because (Ultra Fine Bubbles) is new in Massachusetts. Under a proposed contract with SOLitude Lake Management, costs for equipment, installation and two-year support will be around $32K. OPC will incur additional costs of $3-$4K for unit housing and electrical connections. Monthly operating costs will be about $30.”
Bruce said there is power at the site and access. A six-foot box will house and provide sound-proofing for the oxygenator's motor, which she said will be “about the noise of a pool motor.” She said OPC is sensitive to the comfort of abutters, several of whom sent the commission letters of support. Orleans Conservation Trust land is nearby as well.
SOLitude will provide 24-hour cellular monitoring and visit the site frequently during the experiment. Bruce, who has collected samples from the pond for 17 years, said she will continue that duty. “Should I drop dead next week,” she added, “Lara Slifka is trained and ready to take over.”
Several members of the marine and fresh water quality committee, stressing that they were speaking as private citizens, asked for and received more specifics about the monitoring program, volume of water flows through the aerator, and what would constitute success for the effort.
“There absolutely are numerical things we're looking for,” Wagner said. “We want to see a minimum oxygen level of two milligrams per liter about a foot off the bottom. Beyond that, we want water clarity to improve, and no blooms of potentially harmful algae.”
That would please Bruce, although it would change her view of Sarah's Pond.
“In (a) past year, we had marbleized, scummy algae blooms,” she said. “It's almost beautiful if you don't know what's going on.”