The first-ever tunnel beneath San Francisco Bay will be bored by a joint venture for $215.3 million.

The San Francisco Public Utilities Commission recently awarded a contract for the Bay Tunnel project, which will dig five miles beneath the Bay to create a tunnel for a new water pipe.

The pipe will carry drinking water west from Fremont to San Mateo County for more than 2 million customers in San Francisco and on the Peninsula.

Existing pipelines that stretch over the Bay leak and are vulnerable to earthquakes.

The project is part of the multibillion dollar voter-approved Water System Improvement Program, which is planned to protect fresh water supplies from earthquakes by 2015. www.sfwater.org/WSIP

There are presently no tunnels beneath the Bay. The tube that carries BART trains sits on the Bay floor.