Algae blooms have received a lot of press the summer of 2014 thanks to the massive cyanobacterial blooms in Lake Erie, one of which resulted in the city of Toledo having to stop providing water to the city. In Lake Austin, where the city of Austin derives its drinking water, algae blooms and associated taste and odor problems are closely monitored. The summer of 2014 we saw a larger than normal diatom algae bloom (Fig. 1). However, diatoms are typically harmless and generally do not adversely impact drinking water supply. As with previous years (Fig. 2), in late summer and through the fall we saw the biomass of cyanobacteria increase in lower Lake Austin (Fig. 1). As of January 2015, scientists are analyzing the species composition of the cyanobacteria assemblage to determine if organisms capable of producing toxins are present. But, the bloom was nowhere near the magnitude experienced by the coastal communities of Lake Erie in 2014, and was less than 60% as large as the bloom experienced in the Lake Austin Reservoir in 2013 (Fig. 2). Of interest though was the fact that the cyanobacterial bloom lasted longer in the summer and fall of 2014 than in previous years.
Figure 1. Total algal and Diatom biomass (cells/mL; left axis) and Cyanobacterial biomass (cells/mL; right axis) for the period June 28 through January 11th, 2014 (more data will be added). Austin Water Utility recognizes and monitors a phytoplankton bloom when the total cell count is > 10,000 org/mL (solid horizontal line) and a cyanobacterial bloom is triggered at a count > 300 org/mL (dashed horizontal line).
Figure 2. Algal biomass (cells/mL) based on total cell counts (A); diatoms (B); and cyanobacteria (C) for the summers from 2009 to 2014.