https://en.wikipedia.org/wiki/Powell_Street has: "The street was named for Dr. William J. Powell, surgeon of the U.S. sloop of war Warren, which was active during the conquest of California.[1]".

That comes from this document on the website of the Museum of the City of San Francisco: https://sfmuseum.org/street/stnames5.html

Seems like that would be a good additional source to add to the map.