  We estimate the effect of the spectator charge on distortion of single
charged pion distributions as well as on azimuthal anisotropies in heavy ion
collisions. A large electromagnetic effect on directed flow $v_1$ is predicted
in good agreement with existing WA98 as well as RHIC data. This effect results
in a splitting of $v_1$ for positive and negative pions. Detailed analysis of
this phenomenon may provide new information on the collision dynamics.
