Reusing waste water from the oil field for hydraulic fracturing has become an important topic in the oil and gas industry, and it requires a thorough understanding of both the quality and quantity of the waste water. In this paper, water production from horizontal shale wells in five sections of the Wattenberg field in northeastern Colorado was analyzed. Models were developed for these wells for future water-production prediction. A spatial analysis was also conducted by comparing water production from each section with the gas/oil-ratio (GOR) value for each well. Results indicate that the GOR value of wells has a significant impact on water production in the first year of operation. Wells with low GOR value tend to have higher fracturing-flowback volume and, furthermore, water-recovery rate. Results from this study also provide valuable information for estimating water production from unconventional shale fields, which is critical for the design of wastewater collection and treatment facilities in the field.