The glaciated prairie pothole country of the Midwest forms a vital segment of the most important waterfowl breeding habitat in North America. Here are hatched three-quarters of all the ducks raised in the United States. During a recent seven-year period the three-state area of Minnesota and the Dakotas produced an average of 4 to 5 million ducks annually (Janzon, 1947). This wetland region which once comprised 115,000 square miles in five states had shrunk to about 56,000 square miles by 19.56 (Lynch, 1956). To maintain the pre,;ent rate of waterfowl production in the face of continued destruction of habitat through drainage and other land use practices detrimental to breeding ducks will require that remaining wet lands, particularly those in public ownership, be developed as much .as possible toward their maximum potential for waterfowl production. In recent years the U. S. Fish and Wildlife Service has excavated several hundred experimental artificial potholes and level ditches on its refuges in the Dakotas and Minnesota. It was believed that these water areas would increase the number of ducks breeding on the refuge marshes by providing additional territorial sites. Before more funds are invested to expand this work it is important to determine the success of the existing development in meeting this objective. This study, to evaluate the artificial pothole and level ditch development, was initiated. in 1957 by the U.S. Fish and Wildlife Service at Lower Souris National Wildlife Refuge in North Dakota. The project was carried out in collaboration with the Utah Cooperative wildlife Research Unit and the Department of Wildlife Management, Utah State University.