SAN FRANCISCO (CBS SF) – Drivers traveling to and from Treasure Island will eventually be forced to pay toll in both directions, San Francisco city officials announced.

The toll is expected to take effect in 2021, when new housing units are expected to be complete.

Tolls are expected to be as high as $3.50 on peak weekday hours. Meanwhile, drivers heading to the island from the East Bay would get a discount, since they are already paying a toll to get on the Bay Bridge.

Money from the tolls would go toward a new ferry service linking the island to San Francisco.

Thousands of homes are being planned for Treasure Island in the coming years, as well as retail and hotels.