SAN FRANCISCO—Google has ended a trial run of transporting workers to the company's Silicon Valley campus by water, and it's unclear whether the tech giant will continue the ferry service.

The monthlong pilot program, which took employees from San Francisco's Ferry Building to Redwood City and a five-day ferry servicing employees who live in the East Bay ended Friday.

The San Francisco Chronicle reports ( http://bit.ly/1fNx8kD) Google officials won't say whether service would resume.

In recent months, Google has been at the center of a San Francisco controversy over private buses that several large tech companies use to transport workers to Silicon Valley. Some community members say the buses are congesting city bus stops, so the city recently voted to charge the companies for each stop the buses make.