The scope of area1 investigations of water resources in New York has changed within the last 4 years. Prior 1962, most investigations covered only counties or smaller areas and were mainly restricted to ground‐water resources Since 1762, investigarions have covered largebasin (2,000‐4,000 square miles) with the purpose of defining total water resources so that basin‐wldc comprehensive plans for water development can be prepared. Ground water has been intensively studied in the basin investigations, both because of its large potential for future development, and becaus e of it sinterre lation with the surface‐water resources. The latter reason is particularly important because the principal aquifers are numerous u nconnect edglacials and andgravel deposits that are crossed by streams. This ground‐water regimen to a large degree determines the flow characteristics and water quality of streams. Conversely, streamflow data provide acon‐venient means of assessing ground‐water availability.Some approaches used in basin studies are: (1)(1) numerous quantitative and qualitative observations of low streamflow to define the principal areas of ground‐water discharge and to define the quantity and quality of discharging ground water (2)estimation of total ground‐water dischar gepas stream gages from daily streamflow records by correlation with ground‐water levels and by analysis of the records (3) assessment of recharge to particular sand and gravel deposit swith inbroadlimits, using the data on ground‐water discharge to streams (4) estimation of a daily chemical quality hydrograph on the basis of quantity and quality of both ground‐water discharge and overland runoff.