Elevated cyanobacterial cell numbers (4.7 106 cells/mL) and total microcystins
concentrations (up to 10 mg/L) accumulated in the clarifiers of the treatment plant.
Breakthrough of cells and toxins in filtered water was observed. Also, a total microcystins
concentration of 2.47 mg/L was measured in chlorinated drinking water. Cyanobacterial
cells and toxins from environmental bloom samples were more resistant to chlorination
than results obtained using laboratory cultured cells and dissolved standard toxins.