A systematic study of the dielectric relaxation spectrum of ionic impurities in ice over a wide range of concentrations and temperatures required the development of methods to compare the spectra. The studied impurities fall roughly into two categories, those that increase the dc conductivity of the ice and attendant space-charge effects, and those that suppress these effects. The former were measured with blocking layers inserted between the sample and electrodes, the latter with stainless steel guard electrodes. Linearized plots of the Debye expressions were used for separating up to 4 spectral components by an iterative fitting and correction technique. With blocking layers, the Maxwell-Wagner model of a layered dielectric yields the ice bulk parameters. Analysis suggests that, in general, ice is best described by a small number of discrete components, each characterized by a single relaxation time. Advantages of the blocking-layer technique are experimental simplicity, reproducible values of electrical parameters obtained exclusively from ac measurements, and the systematic coverage possible. The results are useful for evaluating electrical properties of ice in the environment. The model should be applicable to the investigation of rocks other than ice.