Chatham MA Septic: Title 5 and Nitrogen Rules
What the nitrogen rules and the town's own wastewater plans mean for a septic system in Chatham, plus pumping, inspections and repairs.
Nitrogen rules and sewer plans in Chatham
Sewer first, septic second
The question that decides your budget in Chatham is not the state rule, it is whether the town sewer reaches your street before the deadline does. A property that gets connected does not need a nitrogen-reducing septic system at all, and the gap between the two outcomes is tens of thousands of dollars.
For Chatham the designation date is July 7, 2023. The requirement to install Best Available Nitrogen Removal Technology (BANRT) began on July 8, 2025, and the upgrade window runs to July 7, 2028.
The designated systems in Chatham
MassDEP designates by estuary system, not by town line. 2 systems are in Chatham are on the list, and a property counts as inside a designated area based on which watershed it drains into.
| Estuary system | Nitrogen TMDL | Designated |
|---|---|---|
| Pleasant Bay System | TMDL Completed, 2007 | July 7, 2023 |
| Stage Harbor/Oyster Pond, Sulphur Springs/Bucks Creek, and Taylors Pond/Mill Creek Embayment Systems | TMDL Completed, 2009 | July 7, 2023 |
- Stage Harbor/Oyster Pond, Sulphur Springs/Bucks Creek, and Taylors Pond/Mill Creek Embayment Systems — Nitrogen TMDL Report for Five Chatham Embayments (Stage Harbor, Sulphur Springs, Taylors Pond, Bassing Harbor and Muddy Creek)
- Pleasant Bay System — Pleasant Bay System TMDL For Nitrogen (Total)
What the town is building
Chatham has been sewering in phases for years and is still expanding. The Phase 1C-5 Oyster Pond extension is under construction through 2026, the Stage Harbor Road extension is substantially complete, and Phase 1F-1 is scheduled to begin in autumn 2026 and run into 2028.
Chatham is one of the four Pleasant Bay towns.
The Pleasant Bay Watershed Permit, in place since 2018, is the working example the state points to. Four towns share one permit and one nitrogen target rather than each pushing the obligation onto individual owners.
Whether a specific address falls inside a designated area is a question with a definite answer. MassDEP publishes a Natural Resource Nitrogen Sensitive Area map you can check parcel by parcel, and the town is the authority on its own permit status.
MassDEP Nitrogen Sensitive Area map · then confirm the permit position with the Chatham Board of Health.
Local status as of 2026-09-20. Town programmes and permit positions change; the town is the authority on its own.