An algorithm for the estimation of surface chlorophyll-a(chl-a) was developed and validated using the multi-date Landsat TM data as well as the conjunctive in situ data in Lake Shinji and Lake Nakaumi. This highly significant predictive algorithm for surface chl-a is obtained using the TM bands 1, 2, 3, 4, 5 and 7 after dark pixel subtraction as a simple atmospheric correction.