I went to elementary school in Bedford and lived along the Shawsheen River but that was @ 65 years ago. Here's the flood plan link:
https://www.bedfordma.gov/home/pages...ls-for-bedford
I'm an old geezer but, if I have enough grey matter left to express an opinion, I think you would be most concerned about the very west part of town. Also, old buildings in old neighborhoods that weren't built at today's wetlands standards.
I remember there was a swamp at the bottom of Perham and Madardis that they built a church over the swamp. There might have been water problems at least in the parking lot. I think the Shawsheen River ran next to the Bucci farm near the elementary school. I knew one of their kids and we hung together there at the farm and I went to that school. I don't remember any water problems in that area at the time.
I had a very happy childhood in Bedford but people really pay $800k to live there? Lol.