When fracturing slowed last year in the Marcellus, companies holding produced water they did not need for fracturing paid other operators to take it. It provided a cheap source of fracturing water then, and in the future, water trading could reduce the high cost of shipping water. Antero Resources has built a huge plant to turn waste water into fresh water and salt for sale. The $275-million investment in West Virginia is the most tangible indication of how operators in the Marcellus are pushing water reuse. In this work, the authors perform automatic decline analysis on Marcellus Shale gas wells and predict ultimate recovery for each well.