USGS1976
This atlas consists of three maps that show the general distri bution of dissolved solids, hardness, and orthophosphate in the streams and lakes within the Northwest Florida Water Management District. The atlas was prepared in cooperation with the Water Management District to provide pertinent water-quality information relating to the objectives of the Florida State Water Resources Act of 1972. Under the provisions of this act, the Water Management District is required to establish a regional water-use plan, issue permits for water-use and water-resources related construction, and authorize the export of water. The data presented on these maps will be useful to those concerned with water management and use, in assessing regional water quality, and in estab lishing a base for comparison with future quality data. The ranges of concentration shown on the maps represent maximum concentrations in surface water during the sampling period, January 1965-September 1970. Concentrations are plotted at the sampling sites and are the major criteria for determining the extent of concentration ranges. In some cases the drainage basin boundaries are used in defining concentration range boundaries because the quantity and quality of surface runoff is characteristic of the environment of the basin and may be entirely different from the runoff of adjacent basins. Within drainage basins, individual streams and local drainage divides define concentration boundaries. Some areas, although adjacent to each other in the same basin, have entirely different concentration ranges. For example, an area containing dissolved-solids concentrations in the 0-25 mg/1 (milligrams per litre) range may be adjacent to an area in which concentrations exceed 100 mg/1, as in the southwest part of Escambia County. Concentration boundaries in these areas were selected by extending each range about halfway between the two sampling sites, as opposed to grading an intermediate range between them without supporting data. As the data are sparse in many areas, regional concentration patterns are generalized and local variations may be expected to exist.