No Wichita, it's just a "dedicated" area for skiing ... no law against fishing there. (just like there's no law against skiing or fishing anywhere else on the lake ... well, except for the Marina area (fishing) and any other "marked" areas (no wake zones = no skiing). That, and I don't think anyone would try skiing up in some of the creeks ... LOL !! ... hard enough to get a boat thru some of them, under trolling motor power ...heheh !!
I think they thought that by putting in a "dedicated area" and a course ... the ski dudes would stay off the main lake, some ... a little ... well, maybe just a few of them would, anyway. But, twas not to be.

I think the crossed diamonds bouys are just a "warning" to other boats, to be aware that it is a ski area, and to proceed with caution.

.... cp