USGS Water-Year Summary 2021
07130500 ARKANSAS RIVER BELOW JOHN MARTIN RESERVOIR, CO
LOCATION - Lat 38°03'59", long 102°55'55" referenced to North American Datum of 1927, in NW 1/4 NE 1/4 sec.08, T.23 S., R.49 W., Bent County, CO, Hydrologic Unit 11020009, on right bank 0.2 mi downstream from John Martin Dam, 2.6 mi upstream from Caddoa Creek, and 3.5 mi southeast of Hasty.
DRAINAGE AREA - 18,494 mi² of which 785 mi² probably is noncontributing.
- WSP 1241: 1942 (M). WDR-US-2011: Drainage area.
PERIOD OF RECORD - April 1938 to current year. Published as "at Caddoa" prior to October 1947. Statistical summary computed for 1949 to current year, subsequent to completion of John Martin Reservoir.
GAGE - Water-stage recorder with satellite telemetry, concrete control, and crest-stage gage. Datum of gage is 3,737.40 ft above NGVD of 1929. Prior to Feb. 22, 1940, at site 3 mi upstream at datum 22.83 ft higher. Feb. 22, 1940 to Feb. 4, 1943, at site 700 ft upstream at datum 3.64 ft higher. Feb. 5, 1943 to Apr. 8, 1975, at site 1.5 mi downstream at datum approximately 27.5 ft lower.
EXTREMES FOR PERIOD PRIOR TO REGULATION - Maximum discharge, 40,000 ft³/s, Apr. 24, 1942, from rating curve extended above 12,000 ft³/s on basis of flow-over-dam and critical-depth measurement of peak flow, gage height, 10.46 ft, site and datum then in use.