Commentator: Although the present freshwater supply is adequate for today's patterns of water use, the human population will increase substantially over the next few decades, drastically increasing the need for freshwater.
Evidence
The human population will increase substantially over the next few decades, drastically increasing the need for freshwater.
Conclusion
Hence, restrictions on water use will be necessary to meet the freshwater needs of humankind in the not-too-distant future.
Evaluate
The argument concludes that restricting water use will be necessary, but an alternative approach also exists. If additional freshwater could be sourced, then there would be sufficient freshwater and no need for water restrictions.