Occasionally I am asked to speculate on how climate change might impact water quality. It can be difficult to see how groundwater quality (my expertise) will be affected by changing climate. There are some obvious effects, such as saltwater intrusion as ocean levels rise, but that won’t be an issue in Illinois. Groundwater is generally shielded from variations in the weather, and changes in groundwater quality due to changes in temperature and precipitation are likely to be muted and subtle. However, surface water quality is a different story, and a recent article in Nature discusses this. [Michalak, A. M. 2016. Study role of climate change in extreme threats to water quality. Nature 535, 349–350 (21 July 2016) doi:10.1038/535349a]

Probably the most obvious change in surface water quality resulting from climate change is an increase in toxic algal blooms. (The photo above shows an algal bloom in a lake in Illinois during the 2012 drought.) For example, last year Lake Erie experienced its largest recorded harmful algal bloom. While the mechanisms are complex, the main drivers of these blooms appear to be increasing amounts of precipitation, increasing intensity of storms, and warmer water temperatures. These changes, combined with our liberal use of fertilizers in agricultural watersheds, seem to be increasing the number and extent of these blooms. The financial and environmental costs can be huge.

The author of the Nature article is calling for increased attention to study the potential links between climate change and water quality. Increasing communication between climate scientists and hydrologists and hydrogeologists would be a good first step.

My Master’s advisor from Case Western Reserve University, Gerry Matisoff, recently published a paper on phosphorous (the main nutrient causing the algal blooms) in Lake Erie, for those of you who want a more technical study of what’s going on. [Matisoff, G., et al., 2016. Internal loading of phosphorus in western Lake Erie. J. Great Lakes Res. Available online 2 July 2016.]