Mark Albo, 34, died after Daniel Fleischauer, 23, drove down a private boat launch ramp on Flying Point Road on March 11.
Albo was trapped in the submerged Jeep.
Fleischauer was able to get out of the SUV, ran to a neighboring home and asked for help.
Divers were able to get to Albo, but he died at Yale New Haven Hospital, police said. Fleischauer was taken to Yale New Haven Hospital to be treated for hypothermia.
Fleischauer’s blood alcohol level was twice the legal driving limit at the time, police said.
Fleischauer is also charged with operating under the influence of alcohol or drugs, and operating a motor vehicle with a suspended license.