Freedom—October 7, 2020—Cyanobacteria and water quality on Danforth Pond will be on the agenda for a public Zoom meeting to be held tomorrow, October 8, at 7 p.m. Effingham-based Green Mountain Conservation Group (GMCG) will host the event.
N.H. Department of Environmental Services Water Quality Coordinator Jill Emerson will speak about GMCG’s recent water sampling and monitoring on Danforth Pond, as well as the science of how and why cyanobacteria blooms are occurring there.
GMCG’s Outreach Coordinator Moselle Spiller will share proactive steps that shorefront property owners can take to prevent blooms. They include adopting structural best management practices that capture and infiltrate storm water runoff, a major contributor to nutrient loading that causes algal and cyanobacteria blooms. Spiller will share photos and videos from recent installations around Ossipee Lake.
The benefits of preparing a Danforth Pond watershed management plan will be discussed as a road map for future stewardship of the pond. The information covered will be applicable to not just Danforth Pond but any lake in the watershed and the state.
To join the Zoom meeting “Preventing Cyanobacteria: Next Steps for Danforth Bay” click HERE.
Assuming that the climate is warming, and that reducing the amount of nutrients in the lake is unlikely for many years (given there are lots of residual nutrients in the bottom sediments, in addition to what comes from septic systems), then:
Has anyone considered allowing the milfoil to flourish, thus sucking up excessive nutrients, and then cutting it back (approx 4 feet underwater), skimming off the floating milfoil tops and then removing them from the lake to a composting facility? So instead of chemically killing the milfoil (and other vegetation), you treat it as a lawn that is kept mowed? But instead of leaving the grass clippings on your lawn to break down, you’re removing the grass clippings, thus reducing the organic matter and fertility of the soil (or in this case, the lake) over time.
I work at a big garden center in Gorham, ME. I know that if a farmer hays his field more often than every 3 years he will deplete his soil. Maybe instead of spending money to kill the milfoil, why not use it to your advantage? The composting facilities are desperate for organic matter to compost; they recently took a dead minke whale to Benson Farms to be composted to keep up with the demand.
If the lake had a carpet of milfoil (in areas where the depth allowed it to grow) and if it were kept mowed 4 feet below the surface, then that depth wouldn’t interfere with boat props or swimmers. The fish would love the extra cover. Yes there will be a few milfoil floaters that escape the skimming machine, but heck there are always a few floaters anyway, so what’s the difference. No money spent on chemicals and no collateral damage from the chemicals.
Hopefully after a few years the milfoil will have significantly reduced the nutrient load in the lake. I know when we were kids the lake bottom always had this long, fine green grass growing everywhere, but I haven’t seen any of that in years so I suspect the chemicals have killed it. Maybe the milfoil would be a green substitute for the natural vegetation which is mostly gone, and at any rate I’d take milfoil in the lake rather than toxic cyanobacteria any day.
I feel very strongly Martha you are on to something. Purchased a waterfront home (Cottage) on Danforth Pond thirty two years ago and in the past five years I have witnessed the quality of water somewhat deteriorating, first I noticed it from the chemicals used to eradicate milfoil, then this Cyanobacteria. In the past couple of years I have read up on this Cyanobacteria and believe me I am no expert on this subject. But it seems to me we have seen this bacteria appear after the lake (pond) had been treated with the chemicals for the control of Milfoil. It may be coincidental, but I assure you it has happened only after treatment for Milfoil.
One interesting point is that this bacteria (Cyanobacteria) likes PHOSPHORUS, and you know what, when the Milfoil is chemically treated and dies it produces 30 percent phosphorus from the decaying plant. Also, knowing the amount of the Milfoil in the Danforth Pond from the maps received showing the areas of Milfoil, it does not surprise me that this year we had another cyanobacteria outbreak. In my estimation it was due to the large amount of PHOSPHORUS released from the decaying Milfoil plant. Time will tell, next year and years after if there is no treatment of chemical for Milfoil, will we see the cyanobacteria in our Danforth Pond? My best guess would be NO.
I appreciate the idea BUT I think you may underestimate the aggressive nature of this plant. The expectation that the milfoil can be “maintained” with out the risk of overwhelming spread is a risky proposition.
On a separate note could the excess phosphorus be a result of lawn treatment run-off??