The Texas Water Plan (Texas Water Development Board, 1968) proposed development and utilization of water resources in Texas and included a provision for the use and preservation of water in the estuaries of the State. Management of estuarine waters requires knowledge of the hydrodynamics and of the continuing changes in the chemical and physical characteristics of water in the estuaries.

In September 1967, the U.S. Geological Survey and the Texas Department of Water Resources began a cooperative water-resources data-collection program of the principal estuaries along the Texas coast except for the Rio Grande estuary, which is under the jurisdiction of the International Boundary and Water Commission, United States and Mexico.

The data-collection program for the first 11 years were published in 9 separate publications by the Texas Department of Water Resources. This report is the final publication for the project which ended in September 1983, and contains the data collected for the last 5 years (October 1978-September 1983). Approximately 243 data-collect!*on sites were visited during the 1979-83 water years.

The properties or constituents measured in the field were dissolved oxygen (DO), specific conductance, temperature, pH, and transparency by Secchi disk. Analyses conducted in the laboratory included the principal inorganic ions, biochemical oxygen demand (BOD), total organic carbon (TOC), ammonia nitrogen, nitrite nitrogen, nitrate nitrogen, total phosphate, insecticides and herbicides, and other selected metals such as aluminium, arsenic, cadmium, chromium, cobalt, iron, lead, lithium, manganese, mercury, nichol, strontium, and zinc.

Streamfl ow-measuring sites are used to monitor both the amount and quality of water that enter the estuarine embayments. The farthest downstream sites available are located many miles upstream from the estuaries because of the effect of changes in water stage in the estuaries. Consequently, there is inflow into the bays below these sites that can and do affect the amount and quality of water entering the estuaries.