This dataset is a component of a complete package of products from the Connect the Connecticut project. Connect the Connecticut is a collaborative effort to identify shared priorities for conserving the Connecticut River Watershed for future generations, considering the value of fish and wildlife species and the natural ecosystems they inhabit. Click here to download the full data package, including all documentation.

This dataset represents a scaled version of the headwater stream temperature tolerance index based on a model developed by Dr. Ben Letcher and associates at the USGS Conte Anadromous Fish Lab, which is a measure of the relative sensitivity of stream temperatures to rising air temperatures. Specifically, sensitivity is measured by the slope of the linear relationship between air and stream temperatures during the spring season when air temperatures are rising. A steeper slope indicates that stream temperature responds faster to air temperature change, while a shallow slope indicates that stream temperature is more independent of air temperature change. Lower values (i.e., shallower slopes) are interpreted as being more tolerant under climate change, possibly because of groundwater influence or other factors. Conversely, streams with higher slopes are likely to be more impacted by increased air temperatures. In the layer provided here, the raw rising slope index is inverted and (quantile) scaled by HUC6 watershed so that the least tolerant headwater creek (steepest slope) gets a 0 and the most tolerant (shallowest slope) gets a 1 within each watershed. This form of scaling has an intuitive interpretation, because the value of the index expresses the proportion of cells in the same watershed with a value less than or equal to that value. Thus, a value of 0.9 in a cell means that it has a score that is greater than 90% of all the headwater creek cells in that watershed, and all the cells with >0.9 values comprise the best 10% of all headwater creek cells within the watershed. USGS stream temperature tolerance index, as scaled here, is a major component of the aquatic core area selection index in headwater creeks. To learn more about USGS stream temperature tolerance, see Dr. Ben Letcher’s website.