@tjs1295 My husband is a nordic skier originally from outside Wausau and I know there was recently a Faster Skier article titled "Why is US Nordic Skiing so White". My other big hobby is horseback riding and over this last summer I've seen a number of publications discussing diversity and inclusion there too. I don't think it's unique to water skiing.
In both cases, I've seen people break it down into culture, economics, and location. For the most part, these sports just aren't something you stumble into and, even if you do, there are barriers to committing. Not to say they cannot be overcome - it just takes someone with a real interest to follow through on that.