USGS Water-Year Summary 2021
11045700 O'Neill Lake Spill Channel near Fallbrook, CA
LOCATION - Lat 33°19'44", long 117°19'35" referenced to North American Datum of 1927, in NW 1/4 NW 1/4 sec.08, T.10 S., R.4 W., San Diego County, CA, Hydrologic Unit 18070302, on Camp Joseph H. Pendleton Naval Reservation, on right bank, 100 ft upstream from spillway on O'Neill Lake, 1.3 mi upstream from confluence with Santa Margarita River, and 5.5 mi southwest of Fallbrook.
DRAINAGE AREA - 9.77 mi².
PERIOD OF RECORD - October 1998 to February 2003, October 2003 to current year.
GAGE - Water-stage recorder and sharp-crested weir (wooden flashboards in four weir boxes). Elevation of gage is 110 ft above NGVD of 1929, from topographic map.
EXTREMES FOR PERIOD OF RECORD - Maximum discharge, estimation of 725 ft³/s, Jan. 22, 2017, gage height, 8.39ft, from rating curve developed on basis of sharp-crested weir computations; Maximum gage height, 9.32 ft, Dec. 22, 2010; no flow for all or most of each year.