USGS Water-Year Summary 2020
07133000 ARKANSAS RIVER AT LAMAR, CO
LOCATION - Lat 38°06'20.85", long 102°37'05.54" referenced to North American Datum of 1983, in NE 1/4 SE 1/4 sec.30, T.22 S., R.46 W., Prowers County, CO, Hydrologic Unit 11020009, near middle of span on downstream end of downstream bridge on U.S. Highways 50 and 287, and 1.3 mi north of courthouse in Lamar.
DRAINAGE AREA - 19,743 mi² of which 950 mi² probably is noncontributing.
- WSP 1341: 1921 (M), 1945-46 (M); WDR CO-86-1: 1985; WDR-US-2011: Drainage area.
PERIOD OF RECORD - May 1913 to September 1955, April 1959 to current year. Monthly discharge only for some periods, published in WSP 1311. Statistical summary computed for 1949 to current year, subsequent to completion of John Martin Reservoir.
GAGE - Water-stage recorder with satellite telemetry and crest-stage gage. Datum of gage is 3,597.39 ft above NGVD of 1929. See WSP 1731 for history of changes prior to Apr. 4, 1959. Apr. 4, 1959 to Mar. 26, 1968, at site 525 ft upstream on left bank at datum 2.42 ft higher. Mar. 27, 1968 to Nov. 17, 1982, at site 375 ft downstream on left bank at datum 4.00 ft lower. Mar. 18, 1987 to Mar. 6, 2002, at site 75 ft upstream on left bank at same datum. Mar. 7, 2002 to Oct. 20, 2011, at site on left bank at same datum.
EXTREMES FOR PERIOD OF RECORD - Maximum discharge, 73,800 ft³/s, June 18, 1965, from current-meter and timed-drift measurement of peak flow, gage height, 16.48 ft, from floodmarks, site and datum then in use.
EXTREMES FOR PERIOD PRIOR TO REGULATION - Maximum discharge, 130,000 ft³/s (determined by Colorado State Engineer), June 5, 1921, from rating curve extended above 10,000 ft³/s, gage height, 14.55 ft, site and datum then in use.