Bar Harbor, where passenger traffic has risen 257% since 2003, epitomizes the quandary facing coastal communities: How to weigh economic benefits against a fragile quality of life.

A close look at a 2009 study shows passenger spending in Portland was overestimated by at least half, providing a flawed basis for decisions by Maine ports on accommodating the rising number of visits.

Rockland and its transformation catch the industry's eye, and now residents are split over whether to welcome or rebuff mass tourism.

In New England, only Maine allows ships to release treated sewage in most coastal waters, and cruise lines have fought local bans.

The 2009 analysis based its conclusions on every ship arriving at full occupancy, used general scenarios for excursion spending and didn't ask about party size.