In an earlier post I discussed the infamous May 29, 1971 Grateful Dead show at Winterland at which a large number of people reacted adversely to being dosed.
As Corry noted in comments, the Grateful Dead and New Riders of the Purple Sage show scheduled for the night before (May 28, 1971) was canceled due to Jerry Garcia being ill. It was apparently rescheduled for May 30, 1971.
The amazing Gary L. Jackson is having his massive personal archive of SF-related music stuff scanned and shared by "Strength N. Numbers" at Facebook. This includes his personal diaries, which are really quite wonderful. Anyway, here's the entry for May 28, 1971:
I only post this because, well, I like it. And also because it seems like things just weren't going fantastically well right around that time in the Bill Graham enterprise. So much so that the Winterland dosing incident is discussed in contemporary news pieces (some of which were pasted into, and are thus now reproduced in, Gary's diary) as a contributing factor to Graham's seemingly abrupt decision to close the Fillmore West.
Lots of people presumably know lots about this, of course, but I just thought it was worth dropping this part of the picture onto the canvas.