Water resources of the Truk Islands

The Truk Islands, part of the Caroline Islands in the western Pacific, consist of 19 volcanic islands and about 65 coral islets. The volcanic islands and some of the coral islets are scattered in an 820-square-mile lagoon enclosed by a 125-mile long barrier reef. Moen, although not the largest, is by far the most developed island and is the adminstrative, commercial, educational, and transporation center of the islands. Monthly rainfall records for most years are available since 1903. Rainfall-runoff comparisons show that about half the annual rainfall runs off as surface water into Truk Lagoon. Flow characteristics of the major streams, based on more than 11 years of record, are provided and the application of data for possible use in the design of reservoirs and rain catchments is included. Historical and present development of all water sources is given. The chemical analyses of surface and ground water on Moen, with the exception of water from well 9, show the good quality of the water sources. This report summarizes all hydrologic data collected and provides interpretations that can be used for development and management of the water resources. (USGS)