From purpose and scope: This report is the first in a three-part series describing the U.S. Geological Survey's efforts in the detailed hydrologic investigation of southern Nassau and southwest Suffolk Counties, which includes a ground-water modeling study to predict the effects of an extensive sewer network scheduled to be completed in 1985. As the introduction to the series, this report has four objectives: (1) to present a detailed description of the hydrologic system in the area, including newly acquired hydrogeologic information; (2) to define the hydrogeologic factors that will be affected by the sewer network; (3) to explain the modeling strategy and describe the techniques used to develop the ground-water models of the two adjacent areas studied; and (4) to present a preliminary evaluation of the effects of sewers as predicted by a regional ground-water flow model.

From abstract. This report examines flow-duration curves for nine streams in Nassau and Suffolk Counties to evaluate effects of urbanization on streamflow patterns in New York. It contains a map, graphs, and tables.

This report presents the results of a preliminary investigation into the water quality and the relationship between surface and ground-water for the Connetquot Brook basin in Long Island, New York. It contains maps, graphs, and tables.

Purpose and scope: This report depicts in detail the areal extent, altitude, thickness, and lithology of the "20-foot" clay and Gardiners Clay (the two thickest and most extensive near-surface confining layers in the area) and redefines the surface of the geologic units that directly underlie these clay units at various locations--the Matawan Group-Magothy Formation, undifferentiated, the Monmouth Group, and the Jameco Gravel.

This report presents the results of water sampling in two New York counties and concludes that the possibly cause of fluctuations of chloride, sulfate, and nitrate in the water are "precipitation, lawn fertilizer, dissolved salts from storm runoff, and effluent from septic tanks and cesspools." This report also includes a number of maps and graphs.