Estuaries form transition zones between rivers and saltwater environments. On Cape Cod, where we have few, if any true rivers, estuaries are areas partially surrounded by land where ground water and/or marsh streams interface with coastal waters. Estuaries are tidal, brackish or slightly salty, and are often high in sediments. The mixing of sea water and fresh water provides high levels of nutrients both in the water column and in sediment, making estuaries among the most productive natural habitats in the world.
Orleans is fortunate to have three major estuary systems:
- A set of three marshes off of Cape Cod Bay (Rock Harbor, Little Namskaket and Namskaket),
- Pleasant Bay – the largest estuary on Cape Cod, and
- Nauset Estuary / Town Cove.
Our estuaries provide nurseries and habitat for a large number of organisms, including fish, shellfish, terrapins, horseshoe crabs and eelgrass. They are highly productive growth environments. Migratory bird populations depend upon essential food sources in estuaries to fuel their migrations and in some cases to feed their young.
Unfortunately, similar to estuaries all over the world, Cape Cod’s estuaries are being impacted by a number of factors related to population pressure and human activities. Excessive nitrogen from septic systems and fertilizers is causing eutrophication which leads to increasing algae and plant growth. Other factors are man-made pollution from untreated storm water runoff, sea level and temperature rise from global warming, wetland and eelgrass destruction from all of these factors, as well as boating activities and near-shore construction.
Since 2001 the Massachusetts Estuaries Project (MEP) has been studying the Cape Cod estuaries and documenting the dire conditions including decreasing oxygen, increasing nitrogen concentrations, and declining marine life and plants. The MEP analysis has been an important factor leading up to the ongoing sewering and wastewater treatment upgrades in Orleans and other towns on Cape Cod.
In Orleans, the downtown commercial and private residential properties began connecting to the new sewerage system in 2023. Further installation of sewer pipes and connections is ongoing in a phased approach which will take decades to complete. The result of the sewering and wastewater treatment will benefit all the estuaries and freshwater ponds of Orleans. As these projects are implemented over the next few years, the waters of Orleans will begin to see lower nutrient loading that should be reflected in improving water quality”.