A method is presented which combines environmental indices and estimates of inputs from various land uses to aid in environmental impact assessments. Unweighted pair/group cluster analyses are used to obtain relationships between easily observable environmental indices, such as vegetation types, soils, and geology, based on their mutual recurrence. These relationships are shown by using an ordination technique which shows the nature of complex impacts on a natural system. Results are used to develop anenvironmental effects sequence diagram based on known scientific and engineering principles and observed natural relationships. The diagram may be used in conjunction with land use data to estimate the possible magnitude of impacts on the pre-existing system which may result from such land use. Several examples are developed which quantify inputs from various land uses and which compare them with environmental inputs including point source and non-point source liquid and atmospheric emmissions, land modifications, and resource consumption. Known average values are used and a separate comparison is made in describing the vast differences between the project phases of construction versus longterm operation. A hypothetical environmental impact assessment is given for a small residential development in Chambers County, Texas, U.S. of A.