Technical Abstract: A device, consisting of a jar fitted with an inlet comprised of a gas-tight check valve and 2-way ball valve outlet connected via tubing to a portable peristaltic pump, was constructed to collect water samples without atmospheric contamination or loss of dissolved gases. A headspace void for dissolved gas analysis was created by enclosing silicone tubing sealed with rubber stoppers within the jar. The device was deployed in a 0.4 ha lagoon that served as the primary waste recipient of a 2,000 head farrowing operation as well as a 4,000 ha impoundment reservoir. Water samples were analyzed for dissolved methane and common indices of water quality such as pH, suspended solids, various ions, and metals concentration. In addition, lagoon wastewater samples were analyzed for malodorous compounds. For reservoir samples, methane concentrations at the bottom of the lake of 0.49 µg L-1 were about three orders of magnitude higher than at the upper levels of the lake while ammonium levels increased from 0.03 mg L-1 at the surface to 1.67 mg L-1 in bottom samples. pH steadily decreased from 8.92 near the surface to 7.40 at the bottom. Other water quality parameters were similar at each depth. For lagoon samples, ammonium concentration and malodorous compounds declined markedly as temperatures warmed. Results for both reservoir and lagoon sampling indicate that this device affords an inexpensive yet effective means of water collection for subsequent analysis of both water quality and dissolved gas concentration.