The hype about septic systems being the major culprit for the spread of green algae in the embayments, the killing of eelgrass and the cause of hypoxia in Cape Cod waterways is egregiously overdone. Nitrogen emanating from Septic Systems is likely a very small fraction unless the leaching fields or devices are plugged or have otherwise failed to deliver orderly flow into the subterranean. A properly functioning Septic System that has an adequate surface area of biological mat interface will deliver partially treated effluent without overflowing to the surface and short circuiting effluent into surface waters. There are estimates that 80% of nitrogen in waters surrounding the Cape is from onsite Septic Systems. This is totally flawed as there are many other sources of nitrogen, both anthropogenic and natural. There are huge quantities of nitrogen released from vegetation, animals and bacteria that occur in natural systems and from atmospheric deposition. In addition the Boston Deer Island Wastewater Treatment Facility releases vast amounts of Nitrogen into Massachusetts Bay Waters. Further, there are many other nutrients and detrimental compounds from sources other than Septic Systems which affect water quality in Cape Cod water bodies.
Prior to spending billions to install Central Sewer Plants, extensive networks of pipelines and thereby causing major disruptions to natural systems, and possibly doing great harm, a thorough and extensive evaluation is needed to avoid major damage and costs without reducing (or possibly increasing) the environmental damage on Cape Cod.
In Cape Cod, Massachusetts, small ponds in the inland areas and the surrounding waters of the Atlantic Ocean have become increasingly polluted over the years. The main pollutant considered to be problematic in these waters is nitrogen. The large amount of nitrogen in the water stems from the widespread use of private septic tanks in homes instead of the use of a town-owned sewer. This is because many Cape Cod towns opted out of purchasing sewer systems when the federal government subsidized them in the 1960s and 1970s for fear of attracting too many new homeowners to the communities. However, Cape Cod communities still grew despite the lack of public sewage systems, which resulted in the installation of many septic tanks in new homes.
The increased nitrogen levels in the Cape Cod waters has resulted in a greater amount of algae blooming in the spring and summer months, since nitrogen is a nutrient for algae. When the algae die, they leave a thick coat of slime on the bottom of the bays and ponds, which severely reduces the amount of shellfish and crabs able to survive on the seafloor. The algae also limit the amount of oxygen available in the water, which kills the fish living beneath them. The algae are the source of red tides, which have been occurring more frequently with the heightened levels of nitrogen.
To counter the problem, towns are trying to institute new programs and procedures to reduce the levels of nitrogen present in the waters of Cape Cod. A common solution that has been brought up is installing new town-wide sewer systems to prevent runoff from septic tanks reaching the waters, since sewer systems release less nitrogen into the environment than private septic tanks.