The Great Herring Pond and Little Herring Pond Management Plan and Diagnostic Assessment (the “Plan”) was presented to our membership in its final form by consultant Ed Eichner on February 16, 2023. The key results from the study are: 1) phosphorus is the cause of the cyanobacteria blooms in Great Herring Pond, 2) the main source of phosphorus is septic systems, 3) the best long-term way to stop the cyanobacteria blooms is to provide sewer to homes on the north and west sides of GHP and LHP, 4) the largest single source (47%) of GHP phosphorus is LHP, and 5) the largest contributor (87%) is LHP septic.
The report recommended that given the time and expense involved in sewering the needed areas, the HPWA should develop parallel plans for long-range sewering and interim-range alternatives. The Management Implementation Committee (Geri Williams, Jim Smith, Lee Pulis, Tom O’Brien, Brian Harrington, Paul Denoncourt, Jerry Levine, Jack Kedian and Don Williams) plans to investigate a partnership with AD Makepeace to expand their Redbrook package plant to handle the needed Herring Ponds Watershed homes while researching possible interim-term solutions.
Current interim-term solutions under serious consideration are: 1) installation of a permeable reactive barrier (PRB) in the Carters River between LHP and GHP to remove LHP phosphorus before it reaches GHP, 2) initiating a pilot program to install electrolyzed iron plates in septic tanks to inactivate phosphorus, and 3) using a hydrogen peroxide-based treatment to inactivate cyanobacteria. Our consultants will help determine the best option(s) based on cost, effectiveness, length of effectiveness, environmental damage, and ease of permitting.
HPWA is currently taking samples and flow rates that will give us monthly baseline data on the amount of phosphorus in GHP so that the effectiveness of any interim-term solution can be easily evaluated.
Monthly water samples are also being taken to track the presence of cyanobacteria and microcystin toxin in GHP so that cyanobacteria blooms might be predicted in advance. The April and May results are very low, but as we know, these numbers can rise rapidly. In addition, Geri and Don are taking more frequent samples and Geri is using the fluorometer to evaluate trends in phycocyanin (cyanobacteria UV absorbing chemical) concentrations.
Our LHP bog to GHP total phosphorus results show that the GHP total phosphorus through May at least is still quite low; we are hoping for another year with no cyanobacteria bloom.
Finally, Jack and Don took 19 samples from around GHP on June 21st with emphasis on beach areas. They were taken to the lab to be evaluated for E. coli. The results just came in and the counts for CFU’s (Colony forming units) were 5 CFU/100ml or less for all areas tested except in front of the James Circle beach where the count was 100 CFU/ml. According to State DPH 235 CFU/ml is the limit for full body contact, ie. swimming. For drinking water the low risk limit is 0-10 CFU/ml and moderate risk is 11-100 CFU/ml. We will retest the water in front of the James Circle beach this week to see if the condition persists or was just an abnormality. Additional E. coli samples all around the pond will be taken in July and August.