letter to the editor

Thanks for shutting down the siphon

Mon, 08/12/2019 - 4:30pm

Dear Editor:

Ironically legal action taken by Oak Grove Condominiums to shut down the new siphon may have been as good for West Harbor Pond as for the Inner Harbor.

The amount of foul-smelling water upwelling from the siphon outlet this spring, indicated flow through the 6" pipe was unchecked; likely1000+ gallons at dead low tide. Emphasis has been given to the saltwater content of degraded water in the lower depths of the Pond, but the obvious slow rate of mixing of the dark floating plume, suggested high freshwater content.

July/Aug. sampling in the Pond, at 10' depth, reveals dissolved oxygen levels significantly lower than the same months in 2015-18. The freshwater layer supporting aquatic life is measurably thinner this summer.

While attention has focused on the seaside outlet and odor, a more important story may be associated with the intake end of the siphon. Entry is an upturned 6" elbow sitting on a block set at 18' depth. The whirling vortex above this elbow easily extended into the transition zone at 12-15' depth, between good and degraded water.

It now appears likely during periods of high siphon flow, freshwater from above the transition zone was also pulled into the vortex; this would explain the floating effluent plume and a thinner top layer in 2019.

Typically, WHP loses about two feet of water to evaporation during August and early September which of course, is taken from the upper layer of good water. This year thinning of the habitable water may well have been accelerated by action of the new siphon and shut down likely prevented additional loss. The Pond is extremely vulnerable to high temperatures, low oxygen levels, and wind-driven mixing.

Given current circumstances and pending negotiations perhaps some attention should be given to a siphon solution used in Wisconsin - google Restoring Devil's Lake From the Bottom Up.

Sunday morning, Aug. 4 at 6:30 the oxygen saturation level at 10' depth at the DEP sampling station in West Harbor Pond was 28% (2.54mg/l); well into the death zone for fish and other aquatic organisms.

Gary Arnold
West Boothbay Harbor