The construction of Water tunnel No. 3 is intended to provide the city with a critical third connection to its Upstate New York water supply system so that the city can, for the first time, close tunnels No. 1 and No. 2 for repair. The tunnel will eventually be more than long. Construction on the tunnel began in 1970, and its first and second phases are completed. The latter opened with a ceremony under Central Park, in 2013. Completion of all phases is not expected until at least 2021.