Shubael Pond, located in the Three Bays watershed in Massachusetts, is one of many freshwater ponds in the Cape Cod region experiencing an increase in toxic algal blooms leading to pond closures during summer months. These toxic algal blooms, caused by cyanobacteria, are fueled by nutrients like nitrogen and phosphorus entering the groundwater and then surface waters, like ponds. The main controllable source of these nutrients in Cape Cod is wastewater from septic systems.

The Barnstable County Department of Health and Environment and MASSTC joined a partnership with the Barnstable Clean Water Coalition, the U. S. Environmental Protection Agency, and other stakeholders to implement nutrient management solutions in the Three Bays watershed. This project replaced Title 5 septic systems with innovative/alternative (I/A) systems designed to reduce nitrogen inputs from wastewater. These upgrades began with a demonstration project including 14 homes in a neighborhood abutting Shubael Pond.

Shubael Pond, Marstons Mills, MA

This neighborhood was selected for several reasons, including urgency. While this area has seen a troubling increase in algal blooms caused by nitrogen from septic system wastewater, it is not scheduled to be connected to a municipal wastewater treatment plant for 20-30 years. Ecosystems like Shubael Pond may be degraded past the point of possible restoration if nutrient pollution is allowed to continue without mitigation for multiple decades.

Each I/A system that is installed as part of this project is being monitored monthly for nitrogen removal performance. Additionally, groundwater monitoring wells located up and down gradient from participating homes are monitored to determine the aggregate effects of the I/A systems on groundwater pollutants including nitrogen and contaminants of emerging concern. This approach is allowing project stakeholders to evaluate this solution across scales; it is important to determine if this will be a watershed-scale solution.

This effort, led by the Barnstable Clean Water Coalition, has seen the installation of six I/A systems in the neighborhood next to Shubael Pond since the beginning of October 2021.

The initial 14 systems installed in the first phase of this project are KleanTu’s NitROE system. This system was selected because it meets the following criteria: ability to achieve a 90% nitrogen reduction, minimal maintenance required, and it can function as a Title 5 system during periods of power failure. Other systems that can meet these criteria will be included in this initiative in the future.

Download performance data here for enhanced Innovative/Alternative (I/A) septic systems for nitrogen removal installed at Shubael Pond, Marstons Mills (2021 – 2023)

For more information visit the Barnstable Clean Water Coalition’s Shubael Project Page

Want to know more about I/A systems or schedule a tour at MASSTC? Contact us here.

Shubael Pond Project Overview Produced by the Barnstable Clean Water Coalition

Contaminants Addressed

  • Nitrogen