Eni asked if this had anything to do with Turkey or Turkic people. It's named after an individual.
Turk Street was named for Frank Turk, an attorney. He came to San Francisco in 1849, first working for John W. Geary in the post office. He once served as second alcalde.
Although in larger counties today the county judge usually functions solely as county chief executive, in smaller counties, the role of the county judge continues to have many of the combined judicial and administrative functions of the alcalde.