From West Seattle YMCA (WSB sponsor) executive director Shalimar Gonzales:

Due to continued construction in the area, the city will be shutting off the water supply to businesses in the Fauntleroy Triangle, including the Y. We will be closing the West Seattle branch at 8:00 PM on 7/8 (2 hours early than normal), and we will reopen at 6:00 AM on 7/9 (30 minutes later than normal). Fauntleroy is not impacted and will operate as normal.

This is the same water shutdown mentioned in the most-recent Avalon/35th project update.