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Anthropogenic subsurface urban heat islands (SUHIs) in groundwater under cities are known worldwide. SUHIs are potentially threats to springs because much spring fauna, like trout, amphipods, and rare plants, is cold stenothermal. The city of Minneapolis, Minnesota, USA, has a SUHI documented by the temperature of an underground spring, dubbed "Little Minnehaha Falls," inside Schieks Cave, which is located 23 m below the central core of the city. In 2000 the temperature of that spring was elevated 11°C above regional background groundwater temperatures (8°C) at this latitude (45°N). A thermometric survey of the cave and nearby tunnel seepages in 2007 found that an abandoned drill-hole through the bedrock ceiling of the cave was discharging groundwater with a temperature of 17.9°C. By comparison, groundwater in the deep water-table below the cave was closer to natural background temperatures for the region. The unusually warm groundwater was thereby localized to the strata above the cave. This is the strongest signal of anthropogenic groundwater warming in the state of Minnesota and is attributed to vertical heat conduction from basements and pavements. Minneapolis is unique among SUHIs in that a cave forms a natural collection gallery deep below the city surface, whereas the literature is almost exclusively based on data from observation wells.

Past spring inventories have covered certain parts of Minnesota reasonably well; notably, the springs of the Minneapolis-St. Paul metropolitan area and the southeastern Minnesota karst. But hitherto, there has not been a systematic effort to create a uniform statewide inventory. The first step, before hunting down new springs, was to compile existing data and the most fruitful source of hydrological legacy data for the Minnesota spring inventory was the Department of Natural Resources (DNR) Fisheries files. Once entered into a GIS-capable database, these spring locations can help "seed the ground" so that when crews finally do take to the field to map more springs, they will have known examples to work from. Good baseline and time-series data should also help evaluate the impact of climate change and land use changes on Minnesota's springs over time.

The Driftless Area is a designation popular in American promotional tourist literature for an area in four contiguous American states, Minnesota, Wisconsin, Iowa and Illinois, that were not glaciated during the latest ice advance. Geographer Lawrence Martin published several articles asserting that geologist William H. Keating first discovered this area in 1823, an error that has crept into subsequent accounts. But historical evidence goes to show that three geologists, Roland D. Irving, Newton H. Winchell and Thomas C. Chamberlin, were simultaneous originators of the concept as we understand it today, about the year 1877.

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