Northern Prairie Wildlife Research Center
We thank P. W. Shaffer and R. D. Nelson for review of this manuscript, B. A. Hanson and R. A. Gleason for contributing to the design of the water-level recorder, and J. A. Beiser for conducting the statistical analysis. This research was cosponsored by the U.S. Environmental Protection Agency through Interagency Agreement Reference Number DW14935541-01 and the U.S. Fish and Wildlife Service Reference Number 14-48-0009-92-1929.