Stormwater Management: Somerville vs Waltham
How do stormwater management rules compare between Somerville, MA and Waltham, MA?
Somerville and Waltham have similar restriction levels.
Somerville, MA
Middlesex County
Somerville is an EPA MS4 community. Projects disturbing 1 acre need NPDES permits; local review kicks in at 500 sq ft of new impervious surface.
View full Somerville rules →Waltham, MA
Middlesex County
Waltham operates under an EPA MS4 permit and requires stormwater management plans for developments disturbing over 1 acre or adding significant impervious surface.
View full Waltham rules →Key Facts Comparison
| Fact | Somerville | Waltham |
|---|---|---|
| Federal permit | NPDES at 1 acre disturbance | - |
| Local trigger | 500 sq ft impervious | - |
| Design standard | No net peak runoff increase | - |
| Illicit discharge fine | Up to $5,000 per day | - |
| Watershed | Mystic River basin | - |
| MS4 Permit | - | EPA Phase II community |
| Permit Trigger | - | 1 acre or 5,000 sq ft impervious |
| Receiving Water | - | Charles River TMDL |
| Illicit Discharges | - | Prohibited |
| Fines | - | Up to $5,000 per day |
Highlighted rows indicate differences between cities.
Somerville FAQ
I am replacing my driveway with the same area. Do I need stormwater review?
Replacement in kind with no expansion generally does not trigger full review, but switching to a less-pervious surface or expanding the area over 500 square feet does.
Where does Somerville's stormwater go?
Most of the City drains to the Mystic River via MWRA and DCR systems, and some combined sewer areas flow to the Deer Island treatment plant during dry weather.
Waltham FAQ
When do I need a stormwater permit in Waltham?
For any project disturbing 1 acre or more, or redevelopment adding more than 5,000 square feet of impervious surface. Smaller projects may still need Conservation Commission review.
Can I wash my car in my Waltham driveway?
Yes for personal use, but commercial car washing that discharges to storm drains is prohibited. Charitable car washes should use grass areas or dedicated wash bays.
Compare other topics
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