USGS Water-Year Summary 2024

14170000 LONG TOM RIVER AT MONROE, OR

LOCATION - Lat 44°18'47", long 123°17'43" referenced to North American Datum of 1927, in NE 1/4 sec.33, T.14 S., R.5 W., Benton County, OR, Hydrologic Unit 17090003, on left bank, at Monroe, 110 ft upstream from bridge on State Highway 99W, 0.1 mi downstream from Shafer Creek and at mile 6.8.

DRAINAGE AREA - 391 mi².

REVISIONS HISTORY - WSP 654: Drainage area. WSP 1248: 1923, 1927, 1928(M). WSP 1288: 1952.

SURFACE-WATER RECORDS

PERIOD OF RECORD - November 1920 to July 1921, October 1921 to April 1926, November 1926 to May 1927, October 1927 to current year. Prior to October 1930, published as "near Monroe."

GAGE - Water-stage recorder and concrete control. Datum of gage is 273.66 ft above NAVD of 1988 determined by GNSS Level II survey. Prior to Nov. 24, 1944, nonrecording gage at various sites ranging from present site to 1.5 mi downstream at different datums.

REMARKS - Flow regulated since November 1941 by Fern Ridge Lake (active capacity, 93,350 acre-ft). Several small diversions upstream from station. Minor diversion between station and concrete control. Continuous water-quality records and periodic sediment data for some prior periods have been collected at this location.

EXTREMES FOR PERIOD OF RECORD - Maximum discharge, 19,300 ft³/s Jan. 2, 1943, gage height, 17.14 ft, site and datum then in use, from graph based on gage readings, includes some overflow from Willamette River near Junction City; no flow Oct. 20-22, 1944 (water filling pool at gage); minimum discharge observed prior to regulation, 7 ft³/s Sept. 29, Oct. 1, 1939.

WATER-QUALITY RECORDS

PERIOD OF DAILY RECORD - WATER TEMPERATURE: August 2001 to September 2003, September 2019 to current year.

INSTRUMENTATION - Temperature probe and data logger 

EXTREMES FOR PERIOD OF DAILY RECORD - WATER TEMPERATURE: Maximum, 30.6°C June 29, 2021; minimum, 2.6°C Dec. 23, 2022.