That link is for the SCAA standards, and the SCAA links and availability have not changed. It was the SCAE report that went away, which is unfortunate because it had a lot of nicely focused information in 37 pages, including some relevant chemistry fundamentals and illustrative graphics, plus handy conversion tables to help you understand the different measurement units and terminology that so often confuse people. If you just want the gist of the SCAE core zone for espresso machines, it's very briefly summarized in this post
, and discussed a bit in this thread
The full 2011 SCAA Water Quality handbook was never available online, but at least anyone can buy a hardcopy. Getting to the SCAE report right now would cost you a 160 Euro membership. I wish they could make the SCAE report available for a fee, but I suspect the revenue is not worth the hassle of printing hardcopy or setting up a paid PDF download on the SCAE store website.