Effects of small impoundments on stream temperature regimes in the context of a changing climate

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. Further we found evidence that small impoundments can cause local and temporary hypoxia of both impoundment and downstream surface waters, with potential implications for physiological stress and biaccumulation in target species such as brook trout.

Robust estimates of these effects can help managers value dam removals from a climate change adaptation perspective, and help prioritize and justify dam removals using multiple criteria.

Undergraduate Honors Thesis: Chris Smith, 2015. Effects of Impoundments on Stream Temperatures in New England.  Department of Environmental Conservation, UMass Amherst.