Artificial substrates were used to measure differences in macroinvertebrate species diversity at five stations in the Des Moines River in the metropolitan area of Des Moines to assess water quality. Results showed that members of the insect order Trichoptera were the most abundant organisms collected. An analysis of variance for standardized distance (S.D.) values demonstrated significant difference for sampling dates and location of stations. However, when corrected for current velocity, no significant difference was detected for location of stations, but significance over time was retained.