The report covers four years of research on the control of the water quality in a tidal estuary (Penobscot, Maine). Volume 1 of the report contains a brief outline of the work performed and the results. The pertinent technical details are contained in the appendices. Rivers and estuaries are viewed as giant chemical reactors within which certain classes of input materials are processed to form certain other materials. The system developed was based on the assumption that there exists a single measurable attribute that is indicative of the river water quality. It is also assumed that there is a minimum (or maximum) value of this attribute beyond which it is undesirable to go. Further, it is assumed that there is a causative relationship between the amount of material being introduced into the river and the down stream water quality. When these conditions exist, it is technically possible to maintain a river at or above a designated minimum quality. The control of the water quality in a river depends not only on technical factors, but on economic, sociological, and political factors as well.