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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
12150800 SNOHOMISH RIVER NEAR MONROE, WA
LOCATION - Lat 47°49'52", long 122°02'50" referenced to North American Datum of 1927, in NE 1/4 NW 1/4 sec.16, T.27 N., R.6 E., Snohomish County, WA, Hydrologic Unit 17110011, on left bank 150 ft upstream from State Highway 522 bridge, 0.1 mi downstream from confluence of Snoqualmie and Skykomish Rivers, 3.6 mi southwest of Monroe, and 6.0 mi south of Snohomish, at mi 20.4. Instrument box is located in the backyard of 13425 Elliott Rd, Snohomish, WA 98296
DRAINAGE AREA - 1,537 mi².
SURFACE-WATER RECORDS
PERIOD OF RECORD - February 1963 to current year. Water years 1932, 1934, 1951, 1960, 1962-63 (annual maximum stage only) published in WSP 1932. Approximate annual maximum stages for water years 1921, 1949-50, 1952-59, and 1961 are on file in Washington office.
GAGE - Water-stage recorder. Datum of gage is 13.25 ft above NGVD of 1929. Prior to February 1963, crest-stage gage only at site about 800 ft downstream and Feb. 8, 1963, to May 27, 1964, water-stage recorder at site 100 ft upstream, at NGVD of 1929.
REMARKS - Some regulation by powerplant at Snoqualmie Falls, 40 mi upstream, and by Spada Lake, 30 mi upstream.
Minor diversions for irrigation returned to river upstream from gage. The City of Everett diverted an undetermined amount of discharge upstream from the station from Sultan River for municipal use.
Chemical analyses December 1974 to January 1976, July 1979 to September 1986. Unpublished records of water temperature and suspended-sediment concentration are available in the Tacoma office of the U.S. Geological Survey. U.S. Geological Survey satellite telemeter at station. The City of Seattle Water Department diverted an average daily discharge as follows:
| Water Year | Discharge (cfs) |
Water Year | Discharge (cfs) |
Water Year | Discharge (cfs) |
Water Year | Discharge (cfs) |
| 2014 | 77 | 2015 | 72 | 2016 | 66 | 2017 | 71 |
| 2018 | 74 | 2019 | 63 | 2020 | 66 | 2021 | 75 |
EXTREMES OUTSIDE PERIOD OF RECORD - Flood of December 1921 reached a discharge of approximately 180,000 ft³/s. Floods in November or December 1897 and November 1906 are believed to be higher.
EXTREMES FOR PERIOD OF RECORD - Maximum gage height, 35.8 ft, Feb. 10, 1951, datum then in use (discharge not determined); maximum discharge since February 1963, 150,000 ft³/s, Nov. 25, 1990, gage height, 25.30 ft, from rating curve extended above 80,000 ft³/s; minimum daily discharge, 777 ft³/s, Oct. 30, 1987.
