Portland, Connecticut? There Isn't One

There is no town or city named Portland in Connecticut.

You may be thinking of Portland, Maine—the state's largest city, located on Casco Bay. Its elevation is approximately 5 feet (1.5 meters) above sea level at the waterfront, rising to ~200 ft inland.

Connecticut does have a Portland... wait, no—it has Portland as a village in the town of Middletown (Middlesex County), but it's not an incorporated municipality. The Portland, Maine reference is far more common.

If you meant a different Portland (Oregon, Tennessee, Indiana, etc.), specify the state for accurate elevation data.