The problem to be solved is the disposal of millions of gallons of production water (brine water) and flow-back water generated annually from the Rocky Mountain Region oil and gas industry in an environmentally safe, low cost, and efficient manner. A technology that is effective and safe is the evaporation of the water in lined containment ponds after separation and removal of the hydrocarbon component from the water. Four projects are the case studies for this paper, located near the following cities: Cheyenne, Wyoming Cisco, Utah Dad, Wyoming Hobbs, New Mexico They were designed to evaporate water in a series of geomembrane lined ponds. The use of HDPE as the primary liner in the ponds appears to be favorably enhancing the evaporation of the water. At Danish Flats, the estimate of 50 inches of evaporation per year was far exceeded given the 33 inches of evaporation experienced in only July and August 2008, which may have totaled 70 inches for 2008. In years 2009 and 2010, the evaporation rate was over 60 inches. In 2012, the evaporation rate was 42 inches from May through August. The "weep" system was an enhancement to increase evaporation, which was not quantitatively measurable, but may have been a factor in the total evaporation. The deeper ponds at Danish Flats experienced approximately a 30 percent lower evaporation rate due to cooler water at depth. Similarly, the actual evaporation experienced at the Southern Cross project was also more than the pan evaporation estimate based on ponds without the HDPE liner effects, including the increase in evaporation from the estimate of 45 inches per year to nearly 55 inches. It is anticipated that the evaporation rates at Silo Field and CRI will also be enhanced with the use of the HDPE liner as the top layer and the use of the "weep" system along the exposed liner too. The durability and resistance to UV degradation due to the proper amount of carbon black in the geomembrane and other factors as discussed above are the major reasons for the use of the HDPE geomembrane liner as the top layer. The increase with the rate of evaporation due to the black color of the HDPE has been a great benefit and in combination with the "weep" system has realized an increase with the total evaporation at each facility. Some of the liner was installed during the summer months and due to the expansion and contraction of the liner with ambient air temperature gradients, the anchor trenches were only filled during the coolest part of the day to reduce bridging. The leak detection system is used to capture leaks through the primary liner, which worked as designed at the Danish Flats site when a leak was propagated due to ice on the water and the level in the ponds changing which resulted in the ice grabbing onto the pipe and pulling on the pipe boot. The liner was repaired and the leak did not appear again. An existing study was conducted on an HDPE liner installed at a site in Colorado after 20 years of service where the liner was not buried and exposed to weathering, UV light and cooling tower blow-down water. The material was tested for various properties and was found to have no significant reduction in the primary physical properties of the HDPE (Ivy 2002).