By FRANK CARINI/ecoRI News staff
HALIFAX, Mass. — For more than a decade, blue-green algae blooms in West Monponsett Pond have often ended summer fun early and rendered the boat ramp useless. Local residents are regularly cautioned about using the pond, because of harmful health effects linked to cyanobacteria. The Fire Department routinely receives calls about gas odors. The stink is inevitably traced to an abundance of algae triggered by nutrient overloading.
For the past eight years the Massachusetts Department of Public Health has been regularly testing West Monponsett Pond’s summer water quality, but the situation was recognized long before that. The problems and fixes are complicated.
A July 1987 report found increasing aquatic weed growth, nutrient pollution from septic-system leachate, siltation from solids carried in by storm drains and fecal contamination in both East and West Monponsett ponds. The ponds, part of the Taunton River watershed, are separated by Route 58, a 30-mile, south-north highway in southeastern Massachusetts.
Three decades later, the same problems — failed septic systems, stormwater runoff carrying lawn and agricultural fertilizers and animal waste, and phosphorous from bog operations — are causing water-quality impairment and leading to destructive algae blooms. The problem also has been exacerbated by increased development around both ponds during the past 30 years.
Significant levels of these pollutants continue to cause algal blooms that have closed beaches and caused fish kills. Algal blooms with results as high as 1,900,000 cells per milliliter have been discovered; a threshold of 70,000 is enough to close a beach.
Cyanobacteria advisories for West Monponsett Pond have become the norm. These outbreaks are even obvious to untrained eyes, as thick mats of algae choke the pond and color the water pea-soup green….