The U.S. Geological Survey investigated nutrient and trace-element enrichment in Coeur d'Alene Lake, northern Idaho, during 1991-92. The objectives of the investigation were to characterize limnology, quantify hydrologic and nutrient budgets, and develop a nutrient-load/lake-response model. The model required bathymetric data to compute mass balances of water and nutrients within many depth layers in the lake. A review of historical bathymetric data for the lake (Funk and others, 1973; U.S. Environmental Protection Agency, 1977; Milligan and others, 1983) revealed a need for contoured bathymetric data. Therefore, to augment past studies, the U.S. Geological Survey collected extensive bathymetric data and developed a bathymetric map of Coeur d'Alene Lake.