The Henry Darcy Lecture 2009 will address 'Environmental Tracers in Modern Hydrogeology: Reducing Uncertainty in Ground Water Flow Estimation' by Dr. Peter Cook, 2009 Darcy Lecturer, CSIRO Land and Water. Lectures on 'Multitracing of artificially recharged Rhine River water in the coastal dune aquifer system of the Western Netherlands' will be given by Dr. Pieter Stuyfzand, KWR and VU University Amsterdam and on 'Degassing of 3H/3He, CFCs and SF6 by denitrification in the Netherlands' by Dr. Ate Visser, Deltares.