An Ecological Study of the Waterfowl of the Potholes Area, Grant County, Washington

Abstract

The Columbia Basin Irrigation Project will have many effects on the present scene that one encounters in eastem Washington. Not only will the entire economy of a large section of the state be vastly altered, but the superficial appearance of the very land land itself will undergo many changes. One of these changes will be the flooding of a large area of desert sand dunes lying south and west of Moses Lake, Grant County, Washington. At a point approximately ten miles south of the city of Moses Lake and blocking the channel of Lower Crab Creek, the United States Bureau of Reclamation has constructed OYSullivan Dam. This dam is an earthen-filled structure three and one-half miles in length and 100 feet high in some places. Waste water from the irrigation of farm lands to the north and west of Moses Lake will be impounded behind O'Sullivan Dam. Besides this waste water, additional water will be pumped into the area from Roosevelt Lake at Grand Coulee Dam. The lake thus impounded will be a storage reservoir of such size that it will join with Moses Lake. When full this reservoir will raise thle present level of Moses Lake as much as six feet. The lake will be filled to capacity during the spring run-off season and irrigation during the summer will result in the lowest water levels in the fall. The expected annual drawdown from this type of control will range as much as 30 feet (Bureau of Reclamation Officials, personal communication). The sand-dune area to be flooded by the waters behind O'Sullivan Dam at present, contains hundreds of small potholes which have relatively stable water levels. These potholes provided habitat for many species of waterfowl (fig. 1). This study was initiated June 1, 1950. The purpose of the investigation was to establish a mass of basic information about the area which could be used for future management purposes.