France participated to the first and second intercalibration rounds of the Mediterranean Geographical Intercalibration Group (GIG) for phytoplankton in lakes and reservoirs. At the end of the 1st round no WFD compliant index was available to assess the ecological status of water bodies in France. At the beginning of the 2nd round of intercalibration the development of the Phytoplankton Index for Lakes (IPLAC for “Indice Phytoplancton Lacustre”) was initiated, within the frame of a national research program co-funded by Irstea and Onema (The French national agency for water and aquatic environments). Parallel to its scientific development, the IPLAC index was used for method comparison during the whole process in the Mediterranean GIG, with the purpose of achieving intercalibration at the end of the 2nd round. However, due to some mistakes in the index development identified lately, France decided to postpone the use of IPLAC for intercalibration. IPLAC was therefore not officially intercalibrated in the Mediterranean GIG and its scientific development achieved just after the end of the 2nd round. This report evaluates and compares the values of the class boundaries of IPLAC with those agreed during the 2nd round of the Mediterranean GIG for reservoirs.