"August 15, 1975" "The National Ocean Survey was requested by the U.S. Environmental Protection Agency to perform a study relating to the use of tides to assist in determining the area of applicability of the Federal Water Pollution Control Act. Specifically, the National Ocean Survey was asked to determine if there is a correlation between tal datum which is measured and recorded by the National Ocean Survey throughout the coastal United States and the landward limits of the coastal wetlands of the United States as designated by vegetative analysis. In the interest of advancing knowledge of the intertidal areas of the coasts for our charting and coasting mapping function, this Agency performed the study, with the results embodied in this report."--PREFACE FROM R10 ARU. Includes bibliographical references.