, to answer the need for a permanent government agency at the Federal level to conduct, on a continuing, systematic, and scientific basis, investigations of the "geological structure, mineral resources, and products of the national domain." Although a number of laws and executive orders have expanded and modified the scope of the Survey's responsibilities during its 110-year history, the Survey has remained principally a scientific and technical investigation agency as contrasted with a (Developmental or regulatory one. Today the Survey is mandated to assess onshore and offshore energy and mineral resources; to provide information for society to mitigate the impact of floods, earthquakes, landslides, volcanoes, and droughts; to monitor the Nation's ground-and surface-water supplies; t0 study the impact of man on the Nation's water resources; and to provide mapbed information on the Nation's landscape and land use. The Survey is the principal source of scientific and technical expertise in the earth sciences within the Department of the Interior and the Federal Government. The Survey's activities span a wide range of earth-science research and services in the fields of geology, hydrology, and cartography and represent the continuing pursuit of the longstanding scientific missions of the Survey. 1

Surface-water data Groundwater data Meteorological data Interpretive hydrologic investigations CO-83-005 National Trends Network for monitoring atmospheric deposition CO-78-007 Statewide water-use inventory CO-80-131 Evaluation of the Hydrologic Benchmark Network CO-81-158 Regional aquifer system analysis of the Upper Colorado River Basin in Colorado CO-80-165 Effects of energy-production emissions on Colorado lakes 13 CO-83-172 Assessment of water resources and related effects resulting from military training in the Pinon Canyon area, Colorado CO-84-184 An update of fluvial-sediment discharge to the oceans from the United States 16 CO-84-187 Sediment transport and water quality at reservoir sites in western Colorado 17 CO-85-199 Federal Series Reports Preparation Center CO-86-217 Mechanisms of stream recovery from metal contamination CO-87-224 Application of a geographic information system to determine the vulnerability of groundwater resources in the Greater Denver area CO-88-226 U.