USGS Water-Year Summary 2023
16847000 Imong River near Agat, Guam
LOCATION - Lat 13°20'20.4", long -144°20'5.5" referenced to North American Datum of 1983, Guam County, GM, Hydrologic Unit 22010000, located 500 ft upstream from Fena Valley Reservoir, 1.4 mi south of Fena Dam spillway, and 4.1 mi southeast of Agat School.
DRAINAGE AREA - 1.92 mi². from automated delineation using 5-meter digital elevation model, using UTM Zone 55N projection, NAD83 HARN horizontal datum. The 5-m digital elevation model was derived from a digital terrain model, created by Joint Airborne Lidar Bathymetry Technical Center of Expertise, dated May 2007.
REVISIONS HISTORY - WDR HI-10-1: Drainage Area.
SURFACE-WATER RECORDS
PERIOD OF RECORD - March 1960 to March 1971, October 1971 to March 1994, July 1997 to July 2002 (destroyed by flood of July 5, 2002), October 2003 to September 2004, October 2004 to March 2006 (discharge measurements only), and April 2006 to current year. October 1990 to September 2005, unpublished records in files of the U.S. Geological Survey.
GAGE - Water-stage recorder. Elevation of gage is 120 ft, from topographic map. Prior to May 2003 at site 20 ft upstream at datum 10.00 ft higher.
EXTREMES FOR PERIOD OF RECORD - Maximum discharge: 6,100 ft³/s, September 27, 1978, gage height, 11.3 ft, from outside floodmarks and from rating curve extended above 58 ft³/s on basis of slope-area measurements of peak flow. Maximum gage height: 18.55 ft December 2, 2009. Gage height at datum in use since May 2003. Minimum discharge: 0.36 ft³/s, May 7, 2000.
