The Tier system is statewide. There are 4 color coded sections, (tiers).... it's based on the spread of Covid within your county. Purple=Widespread, Red=Substantial, Orange=Moderate, Yellow=Minimum. Currently I think all counties are in Widespread (Purple) except 4... 3 in Substantial (Red) and 1 in Moderate (Orange). Can't really tell on the map but the Tahoe area is either Purple or Red.
Which sports are allowable is divided into each tier.. skiing is allowed in the worst tier (Purple).... I would imagine based on the chance of spreading or catching Covid. Also in Purple - Cross Country, Golf, Swimming, Tennis, Track & Field.
About your last sentence, and social skills... that surprises me. I would have thought skiing GREAT for developing social skills.. you meet so many people, AND from outside wherever your home is. But maybe you mean the 'competitive' side of skiing prevents that, too busy training to interact with one another? The injury part, yes.. that makes perfect sense.
My grandson, still in HS, has begun basketball practice BUT... under guidelines (of course), and knowing the there is little chance for games. Football no practice yet, although it's allowed (under guidelines).... and again little chance for actual games. Baseball is probably the only sport he has a chance of playing this year... and even that is not likely... Fresno County would have to drop a tier to allow it and that's NOT looking very likely.
Very sad for spring sports athletes.... this will be two seasons without.... scholarships are gone, chances of D1 almost nil. - JamesJM