An Assessment of Midwestern Lake and Stream Temperatures under Climate Change

Water temperatures are warming in lakes and streams, resulting in the loss of many native fish. Given clear passage, coldwater stream fishes can take refuge upstream when larger streams become too warm. Likewise, many Midwestern lakes “thermally stratify” resulting in warmer waters on top of deeper, cooler waters. Many of these lakes are connected to threatened streams. To date, assessments of the effects of climate change on fish have mostly ignored lakes, and focused instead on streams. Because surface waters represent a network of habitats, an integrated assessment of stream and lake temperatures under climate change is necessary for decision-making.



This work can be used to inform the preservation of lake/stream linkages, prioritization restoration strategies, and stocking efforts for sport fish. This project employed state-of-the-science methods to model historical and future thermal habitat for over ten thousand lakes. These data were combined with observations of fish and stream temperature data to predict suitable fish thermal habitat. The results of this project can be used by partners and stakeholders to prioritize adaptation and restoration strategies for the region’s freshwater resources. Additionally, these data products can be shared openly in machine-readable formats in order to spur other innovation and research.