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USGS Water-Year Summary 2024
11162630 Pilarcitos Creek at Half Moon Bay, CA
LOCATION - Lat 37°28'00", long 122°25'59" referenced to North American Datum of 1927, San Mateo County, CA, Hydrologic Unit 18050006, on north boundary of Miramontes Grant, on left bank, 50 ft downstream from State Highway 1, 0.3 mi northwest of town of Half Moon Bay, and 1.0 mi upstream from mouth.
DRAINAGE AREA - 27.1 mi².
SURFACE-WATER RECORDS
PERIOD OF RECORD - July 1966 to current year.
GAGE - Water-stage recorder and crest-stage gage. Datum of gage is 31.51 ft above NGVD of 1929 and 34.13 ft above NAVD of 1988. Prior to Nov. 17, 1983, at site 800 ft downstream at different datum.
REMARKS - Flow slightly regulated by storage in Pilarcitos Lake 10 mi upstream, capacity, 3,100 acre-ft. Water is diverted to city of San Francisco water system; small diversions for irrigation upstream from station by pumping.
EXTREMES FOR PERIOD OF RECORD - Maximum discharge, 4,750 ft³/s, Jan. 4, 1982, gage height, 13.08 ft, site and datum then in use, from rating curve extended above 1,000 ft³/s, on basis of contracted-opening measurement of peak flow; maximum gage height, 14.64 ft at current datum, Dec. 31, 2022; no flow at times.
