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Water-Year Summary for Site USGS 11162620

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  • Water-Year Summary reports summarize a year of hydrologic data in a printer-friendly format.
  • For water years 2014 onward, choose a water year and parameter and an on-demand Water-Year Summary report will be generated.
  • For water years 2006 through 2013, choose a water year and an Annual Water Data Report will be provided.
  • For water years 2005 and earlier, Annual Water Data Reports may be available in digital format.
  • Not all sites have reports available for every water year.
Available Parameters
00010 Temperature, water(Min.,Max.,Mean,Med.)  
00060 Discharge(Mean)  

Water year 2023: 2022-10-01 to 2023-09-30

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USGS Water-Year Summary 2023
11162620 Pilarcitos Creek below Stone Dam, near Hillsborough, CA
LOCATION - Lat 37°31'29", long 122°23'54" referenced to North American Datum of 1927, in NE 1/4 SW 1/4 sec.03, T.5 S., R.5 W., San Mateo County, CA, Hydrologic Unit 18050006, on left bank, 50 ft downstream of unnamed tributary, 0.2 mi downstream of Stone Dam, and 2.4 mi southwest of Hillsborough.
DRAINAGE AREA - 6.54 mi².
PERIOD OF RECORD - October 1997 to current year.
GAGE - Water-stage recorder and crest-stage gage. Elevation of gage is 500 ft above NGVD of 1929, from topographic map.
REMARKS - Flow regulated by storage in Pilarcitos Lake, 2.6 mi upstream, capacity, 2,900 acre-ft. Water is diverted by city of San Francisco water system at Pilarcitos Lake and Stone Dam.
EXTREMES FOR PERIOD OF RECORD - Maximum discharge, 408 ft³/s, Jan. 10, 2017, gage height, 7.66 ft, from rating curve extended above 90 ft³/s; no flow Oct. 13, 14, 2001.

WATER TEMPERATURE: Water years October 2008 to current year.

INSTRUMENTATION - Water-temperature recorder since October 2008.
REMARKS - Water temperature rated good to excellent. Water temperature can be affected by releases from Pilarcitos Reservoir.  The practice of assigning qualitative accuracy ratings to water-quality data was discontinued in WY2017.