Powder River Basin (PRB), which covers parts of Wyoming and Montana, is one of the most active coalbed natural gas (CBNG) producing area in the U.S. CBNG production involves pumping water (CBNG water) from coal seams to reduce hydrostatic pressure. It is estimated that cumulative CBNG water production during the period 2002-2017 will be 366,000 ha-m. The CBNG water is dominated by sodium (Na+) and bicarbonate (HCO3-) ions, with sodium adsorption ratio (SAR) ranging from a low of 5 to a high of 70. Clearly management of the enormous quantity of CBNG water is a major environmental challenge. Many of the existing techniques of reducing Na ion concentrations (e.g. ion-exchange, reverse osmosis) often require large industrial columns and filters, treatment equipment, and operation and maintenance efforts that are very expensive. There is an urgent need to find an efficient, but cost effective solution to reduce Na concentrations in CBNG waters so that this enormous quantity of water can be used for beneficial purposes including agriculture. This study evaluated the use of Ca-rich natural zeolites (clinoptilolite), a geologic material with high cation exchange capacity (CEC $1.75 meq/g), as Na exchangers. Deposits rich in Ca zeolites (80-90% clinoptilolite) were identified and representative sample of zeolites were collected from different deposits. The CEC of representative zeolites materials were determined. Zeolite samples occurring in large volumes, high in mineral purity, rich in Ca and with CEC characteristics capable of supporting a substantial water treatment program were used to study the exchange reactions with CBNG water with varying SAR values. The results of this laboratory study will be used to design an economically viable and efficient CBNG water treatment plants in the PRB region.