310 CMR 15.215(4)
Before you sell a Cape Cod home on septic, you must tick one of these boxes.
Massachusetts requires the seller to disclose — to the buyer and the town's Board of Health — whether the property needs a nitrogen-reducing septic upgrade. Exactly one statement applies. Getting it wrong is your problem, not the state's.
- Is in a Nitrogen Sensitive Area and is subject to the upgrade requirement.
- Is in one, but not subject, because the town filed for that watershed.
- Is in one, but not subject, because nitrogen-reducing technology was already added.
- Is not in a Nitrogen Sensitive Area.
The state publishes a map that answers roughly a third of that. It shows whether you are inside one of the 35 designated watersheds — but not whether your town has filed for your watershed, which is what separates box 1 from box 2. Those two facts live in different documents that do not reference each other.
This site puts them together.
Where things actually stand
Fourteen of the fifteen Barnstable County towns have a designated watershed. As of the MassDEP table dated 11 June 2026, every one of them has filed something — so the upgrade requirement is currently suspended across the Cape.
That is the good news, and it is worth being precise about how far it goes. A Notice of Intent is a pause, not a resolution. It runs on a schedule of milestones approved by MassDEP, and if a town misses them the five-year clock starts. A granted permit is a much stronger position than an intention to apply for one. Four different filing types are in play across the Cape, and they do not carry equal weight.