Water is a critical commodity in short supply in arid environments. Therefore, its judicious use and disposition is critical for improving the environment both economically and esthetically. Two desert shrubs, creosotebush and tarbush, have invaded former productive grasslands and intercept rainfall that would normally enter the soil and be available for the growth of useful plants. A creosotebush community with 30 per cent crown cover would intercept 12 per cent of the summer rainfall. Native communities of tar bush with approximately 15 per cent crown cover would intercept 6 per cent of the average summer rainfall.