I don't believe the percentages are quite that high. I have seen them somewhere in past DD and believe the indians' royalties are around 17.5%, higher than average, but not substantially.
I also believe there are efforts being made to 'negotiate' better rates on the state taxes on oil and gas.
All combined, seems I remember the percentages NVMG will be paying out are approx. 5% more than the norm, which though is nothing to smile about, is also nothing to be alarmed of.