Ing Agronomo

A Procedure
for Evaluating
Environmental Impact

By Luna B. Leopold, Frank E. Clarke,
Bruce B. Hanshaw, a n d James

R.

Balsley

GEOLOGICAL

SURVEY

CIRCULAR

645

Washington 1971

United States Department of the Interior ROGERS C. B. MORTON, Secretary

Geological Survey
V. E. McKelvey, Diredor

First through fifth printings 1971 Sixth and seventh printings 1972 Eighthand ninth printings 1973

Free on application to the U.S. Geological Survey, Washington, D.C. 20244

FOREWORD

Man cannot survive on this planet without utilizing its natural resources prudently. Every human action affects the world around us in some degree and the full effect is difficult to assess because of complex relations among living and nonliving things. Under the circumstances onecan neither expect to restore the entire past nor preserve the entire present for future generations. However all can and should strive for proper balance between resource development and maintenance of pleasant surroundings. The Environmental Policy Act of 1969 and the reports on environmental assessment t h a t i t requires are aimed at insuping such a balanced approach. To be effective we mustprovide a system for relating large numbers of actions and environmental factors and for placing value judgments on impacts which are difficult to quantify. A t my request the Geological Survey has developed a n information matrix system that is described and modeled in this Circular. It is published with the thought that it will serve as a useful guide for environmental impact reporting and as asystematic reference. Those who share with us the desire to retain or improve the quality of our environment will recognize that this report is a sincere but still preliminary effort to fill a n interim need. We hope that suggestions from others will improve this framework.

ROGERS B. MORTON C.
Secretary of the Interior

A Procedure for Evaluating Environmental Impact
By luna 8. Leopold,Frank E. Clarke, Bruce B. Hanshaw, and James
PREAMBLE

R.

Balsley

In a recent article in “Science” discussing the Environmental Policy Act of 1969, Gillette (1971) states “The law’s instructions for preparing a n impact report apparently a r e not specific enough to insure that a n agency will fully o r even usefully, examine the environmental effects of the projects i t plans.” Thisreport contains a procedure that may assist in developing uniform environmental impact statements. The Department of the Interior and the Council on Environmental Quality will appreciate comments on the procedure here proposed. The heart of the system is a matrix which is general enough to be used as a reference checklist o r a reminder of the full range of actions and impacts on the environment t h at may relate to proposed actions. The marked matrix also serves as a n abstract of the text of the environmental assessment to enable the many reviewers of impact reports to determine quickly what a r e considered to be the significant impacts and their relative importance a s evaluated by the origina. tors of the impact report. Many exhaustive studies of the use of matrices for environmentalstudies are now being undertaken. (See Sorensen, 1971.) This comparatively simple system is intended a s a guide for the many people who are faced with the evaluation and preparation of environmental impact reports before the results of these studies have been completed. It should be borne in mind t h a t there is presently no uniformity in approach o r agreement upon objectives in a n impact analysisand this generalized matrix is a step in t h a t direction. The procedure does not limit the development of detail in any specific aspect of the environment; a separate expanded matrix for any environmental aspect can easily be developed within the framework provided.

INTRODUCTION

In any proposal for construction o r development, it is the usual practice, both from the standpoint of...