SEATTLE — Menu prices are up 21 percent and you don’t have to tip at Ivar’s Salmon House on Seattle’s Lake Union after the restaurant decided to institute the city’s $15-an-hour minimum wage two years ahead of schedule.

It is staff, not diners, who feel the real difference, with wages as much as 60 percent higher than before. One waitress is saving for accounting classes and finding it easier to take weekend vacations, while another server is using the added pay to cover increased rent.

Seattle’s law, adopted last year after a strong push from labor and grassroots activists, bumped the city’s minimum wage to $11 beginning April 1, above Washington state’s highest-in-the-nation $9.47. Scheduled increases that depend on business size and benefits will bring the minimum to $15 within four years for large businesses and seven years for smaller ones.

There’s little data yet on how the law’s working.

“To the extent that we can look at macro patterns, we’re not seeing a problem,” said Seattle Mayor Ed Murray.