USGS Water-Year Summary 2022
16704000 Wailuku River at Piihonoua, HI
LOCATION - Lat 19°42'43.7", long 155°09'02.7" referenced to North American Datum of 1983, Hawaii County, HI, Hydrologic Unit 20010000, on right bank 0.2 mi downstream from Hookelekele Stream, 0.9 mi west of Piihonua, and 4.1 mi west of Hilo Post Office. Prior to November 16, 1977, at site directly across river, on left bank.
DRAINAGE AREA - 220 mi² of which 71.4 mi² probably is noncontributing. from automated delineation using 10-meter National Elevation Dataset digital elevation model data dated September 2006 and Watershed Boundary Dataset dated May 2008, using UTM Zone 4 projection, NAD 83 horizontal datum.
- WSP 865: 1929-36(M). WSP 965: 1941. WDR HI-80-1: 1929-79(P). WDR HI-81-1: 1940(M). WDR HI-10-1: Drainage Area.
PERIOD OF RECORD - July 1928 to July 1940, October 1940 to December 1947, April 1948 to current year. Monthly discharge only July 1928, published in WSP 1319. Prior to July 1960, published as "above Hilo Boarding School ditch intake, near Hilo."
GAGE - Water-stage recorder. Elevation of gage is 1,080 ft above mean sea level (from topographic map). Prior to November 16, 1977, at site directly across river, on left bank, at same datum.
EXTREMES FOR PERIOD OF RECORD - Maximum discharge, 82,300 ft³/s, August 23, 2018, gage height, 24.40 ft; minimum, 0.15 ft³/s, January 20, 1981.