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- Water-Year Summary reports summarize a year of hydrologic data in a printer-friendly format.
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USGS Water-Year Summary 2024
11458000 Napa River near Napa, CA
LOCATION - Lat 38°22'06", long 122°18'08" referenced to North American Datum of 1927, Napa County, CA, Hydrologic Unit 18050002, in Yajome Grant, on left bank, downstream side of Oak Knoll Avenue Bridge, 0.4 mi downstream from Dry Creek, 5 mi north of Napa, and 12.8 mi downstream from Conn Dam.
DRAINAGE AREA - 218 mi².
REVISIONS HISTORY - WSP 1315-B: 1930 (instantaneous maximum discharge). WDR CA-87-2: 1963 (instantaneous maximum discharge), 1965 (instantaneous maximum discharge), 1967 (instantaneous maximum discharge), 1982-85. WRD CA-01-2: 2000 (instantaneous maximum discharge).
SURFACE-WATER RECORDS
PERIOD OF RECORD - October 1929 to September 1932, October 1959 to current year. Monthly discharge only for some periods, published in WSP 1315-B.
CHEMICAL DATA: Water years 1973-93.
BIOLOGICAL DATA: Water years 1978-81.
SPECIFIC CONDUCTANCE: Water years 1978-93.
WATER TEMPERATURE: Water years 1977-93, 2018.
SEDIMENT DATA: Water years 1971, 1977-93. TURBIDITY Water year 2018.
GAGE - Water-stage recorder. Datum of gage is 24.74 ft above NGVD of 1929 and 27.14 ft above NAVD of 1988.
REMARKS - Flow regulated by Lake Hennessey beginning in December 1945, 12.8 mi upstream, capacity, 31,000 acre-ft; Rector Reservoir beginning in 1948, 12.4 mi upstream, capacity, 4,400 acre-ft; Bell Canyon Reservoir beginning in 1959, 19.6 mi upstream, capacity, 2,530 acre-ft. Diversions for irrigation upstream from station of about 10,000 acres.
EXTREMES FOR PERIOD OF RECORD - Maximum discharge, 37,100 ft³/s, Feb. 18, 1986, gage height, 30.20 ft, from floodmarks, maximum gage height, 30.50 ft, Mar. 9, 1995; no flow many days most years.
