Across the United States, millions of small dams fragment the landscape and alter stream ecosystems. Dam removal is increasingly used as a strategy to remove obsolete structures and to mitigate negative impacts to humans and ecosystems. The northeast and northcentral US have the highest density of small dams, along with the most active removal programs. The increasing pace and scope of dam removal projects, coupled with uncertainties surrounding climate change impacts on rivers, suggest that management agencies will be faced with decisions about the prioritization and funding of restoration projects in the context of a changing climate. Climate change is expected to alter flow regimes, shifting peak flows to earlier in the water year and increasing the magnitude and frequency of storm events, while also contributing to seasonal droughts. Stream temperatures are expected to increase with climate change, and heat-sensitive taxa, such as brook trout, may be at risk of local extirpation

The Driftless Region is blessed with an exceptional coldwater fishery (native brook trout and non-native brown trout).  Based on statistical modeling, it has been predicted that over the next 50 years brook trout will virtually disappear from the region and areal extent of brown trout will decrease significantly.  However, these predictions do not account for potentially significant increases in groundwater recharge and hence in baseflow as a result of likely increases in fall through spring precipitation and potential decreases in winter frost.  Nor do they account for the fact that baseflow in the Driftless Region is due mainly to thousands of springs, many of which are supply streams with relatively small drainage areas (e.g., less than 10 km2).  Empirical evidence suggests that flow from these springs as well as from in-channel seeps persists at anomalously high rates during droughts, such as the severe drought of 2012

Small dams and impoundments are ubiquitous in stream networks in the northeastern and north central US.  Concerns about their effects on stream fish population connectivity and their risks to human infrastructure and safety have prompted efforts to remove many of these dams.  Dams also have  potentially significant impacts on stream thermal regimes, and as a consequence their removal may either ameliorate or exacerbate effects of increasing air temperatures.  Also, given their ubiquity, temperature modeling and monitoring efforts need to account for the effects of small impoundments for assessment and prediction. From the results of the first two seasons of field work, it appears that the direct effects of impoundments may persist considerable distances downstream and that these effects are flow-dependent