Landscape effects on stream temperature in Minnesota streams of the Lake Superior basin

Changes in land use and land cover are known to be important factors causing thermal alterations in small streams.  The heating of cold and cool water streams influences aquatic communities that inhabit such environments.  We recorded continuous stream temperature data at 52 sites, during July – September of 2008, to better understand thermal controls on small streams (1^st – 3^rd order) within Minnesota’s Lake Superior watershed.  Local and landscape variables were used to predict in-stream temperature using multiple regression analyses.  These analyses indicate the extent to which the water storage capacity of a watershed can mitigate the effects of impervious surface cover on thermal trends in streams.  Sites were selected to represent natural gradients of water storage capacity (0-82%) and impervious surface cover (0-27%) within each sub-watershed.  Stream habitat data were collected to explain natural temperature variation between sites due to local conditions.  Preliminary analyses suggest that diel stream temperature fluctuations are moderated in catchments with greater water storage capacity.  Analyses also indicate that maximum, and average in-stream temperatures are negatively correlated with water storage capacity.