In summer 2007 & 2008, 100 water samples were collected from 10 freshwater reservoirs with cyanobacteria issues. Phytoplankton was determined according to the Utermohl method [1]. Intra- and extracellular CYN, ATX-a, STX were analyzed by LC-MS-MS or HPLC-PDA at UBA, and in addition, Veolia tested Abraxis ELISA kits for total CYN and total STX on the 2008 water samples (n=45). Cyanobacterial abundance was comparably low in 2007 & 2008 for all reservoirs, probably because of cooler summer months, with less sunlight, more rain and quickly decreasing fall temperatures (except in reservoir 10, which had low incoming nutrient charges). For instance, average chlorophyll content was 12 µg/L in 2007 and 35 µg/L in 2008 in Western France, when 60-80 µg/L concentrations are usually measured. In spite of these environmental conditions, cyanobacteria were detected in 97% of the samples and cyanotoxins in 55%. WHO level 3 for drinking water (>100 000 cell/mL) was reached for 20-25% of the samples. Among the species observed in the water samples, the following potential CYN, ATX-a, STX producers were observed: Cyanotoxin LC-MS-MS and HPLC-PDA results are given on the right. ELISA results for CYN and STX of the 2008 samples only partially agree with the LC-MS-MS data. This might be due to the differences in extraction procedures of the two methods, cross-reactivity issues of the ELISAs for derivatives, in combination with overall very low concentrations of the toxins.