i was there on monday afternoon, when the water was at 850 cumecs for all i know, which was the highest level ever.
both waves were gone. the lower wave was still a bit of a wave, but too flat and too fast, and the island was 1 meter under water, so there was no eddy...
i think it's now back to 468. see
www.bwg.admin.ch/service/liste/d/index.html
(under reuss, mellingen).
I think the lower wave should be surfable at this level, although it's probably rather flat and still fast (but i have't seen it for myself since monday).