>> reporter: dive teams were called in to perform rescues. >> you need another hand? >> but it was neighboring depending on neighbors to reach dry ground. this is what paul talbot saw outside his front door. >> we're from new england. we've been through some of the worst blizzards, rainstorms. >> reporter: he's ridden out hurricanes before, this was different. >> i've never seen rain lake this come down for so many days, just nonstop. >> reporter: with part of the university of colorado campus underwater, hundreds of students were ordered to higher ground. >> we are pleading with students and people on this campus to stay indoors. >> 12 dams have overflowed, sending a wall of water downstream. >> when the water came through, it came through as a torrent. >> reporter: 7.2 inches of rain fell in less than 24 hours. an all-time record. >> this is insane. >> yep. >> reporter: floods have devastated this region before. in 1976, the big thompson flood killed 145 and cost $40 million