Large expanses of land across midcontinental North America have been heavily modified by installation of artificial drainage to convert prairie pothole wetlands into tillable areas. Drained potholes are observed as sheetwater wetlands in agricultural fields, are valued by migratory waterbirds, and have only been studied in limited contexts. We evaluated the use of agricultural sheetwater to migratory waterbirds in Iowa’s Prairie Pothole Region and hypothesized that wetland size would be an important predictor of waterbird use. We observed 1913 unique wetlands and documented waterbird use on 31% of observations of those wetlands. The most frequently detected waterbirds were Killdeer, Mallard, Blue-winged Teal, and Lesser Yellowlegs. Wetland size had a positive effect (P <0.05) on waterbird species richness and abundance. The findings from this study will help inform future decisions on drainage practices and their impact on wildlife and indicate the need to examine this habitat type at larger temporal and spatial scales.