BF finally came home and we accessed the main shut-off valve between the house and the studio. The water is turned off to the studio, which is a very minor inconvenience. Better to have no bathroom there for a day or so than to pay $300 to a plumber for what I can do myself. The distance between the two buildings is 25 feet.
I have a couple very small cleaning/organizing projects I want to finish over there, and then I'm going to read.
I'll make the water line repairs tomorrow or Thursday, once the ground dries out.