A comprehensive evaluation of elemental contamination was done on the Alamose/Monte Vista national Wildlife Refuge, San Luis Valley, Colorado,during 1989-90. Water, sediment, mallards, mallard eggs, American coots,and mallard food items were collected for elemental analyses. In addition, adult mallards were collected during winter and 20 different tissues were removed for histological analysis and diagnosis of avian cholera. Copper and zinc from several sources exceeded aquatic life standards for the Rio Grande River Basin. Acute toxicity tests using Ceriodaphnia dubia as the test organism were performed on water samples during both years. In 1989, mortality of the test organisms for all samples was less than 20%. In 1990, a sample from well #7 resulted in 44% mortality and a sample from well #5 resulted in 33% mortality.Chemical characteristics of all water samples were within normal ranges for wetlands during both years.