Of all the concerns in mezcal production sustainability--cultivated agave, agaves sylvestres (wildcrafted), firewood, and vinazas, the vinazas rank second in my opinion. Let me rephrase--if we count Tequila as a mezcal--vinazas are the #1 problem, but if we are talking about Mezcal (capital M--certified product, excluding Tequila), it's fortunately less of a problem.