Comprehensive inspections performed at the water intake of CESP’s Jaguari hydropowerplant, raised the possibility that cracks in concrete could have been caused by alkali-aggregate reaction. Triortogonal joint meters were installed and cores extracted for petrographic analysis, proving that cracks were caused by AAR and that actions were needed to evaluate the level of expansion and the structural behavior of the intake. A monitoring system comprising rod extensometers, crack meters, triortogonal meters, LVDT was provided and a new optical instrument was developed to check movements. Drilled cores were sent to the laboratory to be subjected to petrographic analysis, expansion tests, compressive strength and modulus of elasticity. AMBT, CPT and ACPT tests were also performed. In order to check the occurrence of gel a staining technique was applied in the concrete. This paper summarizes the research and development project that is allowing CESP to better monitor and study the intake.