I worked in the snowmaking industry at ski resorts for more than a decade before getting into tech. Many ski resorts have a snowmaking reservoir at elevation and a pumping system to fill it (usually off peak) and then use gravity to actually feed the snowmaking guns (at least partially). Almost every snowmaking manager (that I talked to) has had the idea at some point to try some sort of pumped hydro offset, but I'm unaware of anyone who has actually tried it. It would be fairly small scale (reservoirs can be ~20 million gallons, usually less) but it would be interesting to see the economics of it because the infrastructure is already there (pumps, pipes, reservoirs, etc). The systems generally even sit unused for 7-8 months of the year.

I think some of the challenges are that while most resorts have a fairly massive pumping system, it's usually geared towards slowly filling the reservoir, with the rest direct feeding the snow guns. Not many places have the need to fill a 20 million gallon reservoir in a couple of days.

There's also the probability that the head pressure's wouldn't work out. Gravity feeding from an upper reservoir near the top of a large mountain can result in thousands of PSI at the bottom if not passed through a series of pressure relief valves. I'd imagine ideally you would have to build a generating station and a new catch reservoir at the perfect elevation because if you are pumping a lot higher than needed the efficiency is going to drop significantly.