Hydrological map of the Big Island of Hawaii, engraved and
published by the United States Geological Survey in 1913. This map illustrates
the island’s complex drainage basins and river systems, offering a rare glimpse
into early 20th-century hydrological understanding of Hawaii. It was issued as
Plate 15 of Water-Supply Paper 318 (as noted in the upper right), a key
component of the USGS publication Water Resources of Hawaii, 1909–1911
by W. F. Martin and Charles Henry Pierce.

A rich array of hydrological features is displayed.
Stream-gaging stations, crucial points for monitoring water flow and volume,
are marked with red circles. Rainfall stations, which track precipitation
levels, are indicated with black circles, while evaporation stations—used to
measure daily water loss through evaporation—are denoted with red and black
circles.

The island is divided into its traditional districts, with
district boundaries and the coastline highlighted in red. Mountain ranges are labelled
and accompanied by their elevations in feet, while rivers are named throughout.
The map also identifies various significant locations, including bays, harbours,
plantations, and towns.

The map was produced under the directorship of George Otis
Smith, who led the USGS from 1907 to 1930; his name appears in the upper left
corner of the map. As further testament to its governmental significance, the
map was also presented as House Document No. 1345 during the 3rd Session of the
62nd United States Congress (1912–1913).

Data for this map was compiled from earlier cartographic
records held by the Hawaii Territory Survey, supplemented with additional
miscellaneous sources, as noted in the lower left margin. It reflects the
USGS’s broader mission, as an agency of the U.S. Department of the Interior, to
document and understand the landscape, natural resources, and hydrological
systems of the United States. Founded in 1879, the USGS has long conducted
vital programs in hydrology, including stream-gauging and water-quality assessments.