The Storrow Drive Tunnel, through which Storrow Drive runs along the Esplanade just north of Clarendon, Berkeley and Arlington Streets, has been deteriorating since it was built in 1951. By mid-2007, the Department of Conservation and Recreation determined that repairing the tunnel may be impossible because it was not waterproofed when it was built, and damage in the intervening years has been significant. Consequently the tunnel may have to be rebuilt at a cost upward of $200 million, a project that would require closing critical sections of Storrow Drive to traffic.