Impact of Climate Change on Harmful Algal Blooms at Chautauqua Lake

Chautauqua Lake is situated in Chautauqua County, New York and it plays a vital role in providing drinking water in the region. However, its North and South basins have been affected by elevated nutrient and algae levels leading to the formation of Harmful Algal Blooms (HABs). There are several HABs events which occurred since 2012 (https://www.dec.ny.gov/docs/water_pdf/chautauquahabplan.pdf). Some of the factors which may be contributing to the rise of HABs in Chautauqua Lake are, increased phosphorus concentrations which may be related with the changes in agricultural practices, poorly maintained wastewater treatment and septic systems or increased demand on them. Other factors may include internal loading of phosphorus, and stormwater runoff.

In addition to the rise in HABs events, a changing climate is potentially causing a change in the Chautauqua Lake ecosystem. Locally, climate change has led to higher temperatures and increased precipitation, including more extreme events. Consequently, this increase in precipitation resulted in higher runoff, carrying more nutrients into the lake, thereby promoting formation of HABs. To address these challenges, it is crucial to adopt appropriate best management practices that consider the impact of climate change.

We examine the potential effects of climate change on the recent increase in high HABs events at Chautauqua Lake. For this purpose, extreme high HABs years will be compared and analyzed with low HABs years using several atmospheric drivers. Preliminary analysis using ERA5 data indicates that in 2017, spring precipitation was higher than the 30-year mean leading to higher runoff which stands in contrast to a low HABs year (2012) characterized by low precipitation and runoff. Other atmospheric drivers will also be analyzed to assess the impact of change in climate on the occurrences of HABs events. We will also report on further analysis to investigate seasonal changes and their impact on these HABs events.