05443500 DATA: Discharge Tables, 1998

ROCK RIVER BASIN

05443500 ROCK RIVER AT COMO, IL

LOCATION.--Lat 41°47'00", long 89°44'58", in NE1/4NE1/4 sec.25, T.21 N., R.6 E., Whiteside County, Hydrologic Unit 07090005, on left bank, 1 mi upstream from Como, 3 mi downstream from Rock Falls, 3.5 mi upstream from Elkhorn Creek, and at mile 69.2.

DRAINAGE AREA.--8,753 mi².

PERIOD OF RECORD.--March to December 1905, October 1914 to September 1971, water years 1972-77 (annual maximums), October 1977 to September 1986. Water years 1987-90, seven-month period (March to September). October 1990 to current year. Published as "at Sterling" 1905-6 and as "at Lyndon" 1914-34. Records published for both sites December 1933 to September 1934. Monthly discharge only for some periods, published in WSP 1308.

REVISED RECORDS.--WSP 1308: 1915(M), 1917-18(M), 1922(M), 1924(M), 1926(M), 1928(M), 1931-32(M), 1934(M). WDR IL-79-1: Drainage area. WDR IL-97-l: 1996 (Dec. 12-23).

GAGE.--Water-stage recorder and crest-stage gage. Datum of gage is 606.83 ft above sea level. Jan. 6, 1905, to Feb. 17, 1906, nonrecording gage at Sterling, 3 mi upstream, at different datum. Nov. 24, 1914, to Sept. 30, 1934, nonrecording gage at Lyndon, 16.5 mi downstream at datum 22.46 ft lower.

REMARKS.--Records good except those for Nov. 17-21, which are fair, and those for estimated daily discharges , which are poor. Some diurnal fluctuation caused by powerplants upstream from station. Gage-height telemeter at station.

EXTREMES FOR PERIOD OF RECORD.--Maximum discharge, 59,700 ft³/s, Apr. 21, 1973, gage height, 15.66 ft, from rating curve extended above 41,200 ft³/s; maximum gage height, 17.51 ft, Feb. 7, 1938, backwater from ice; minimum daily discharge, 440 ft³/s (498 ft³/s, site then in use), Aug. 20, 1934.

DISCHARGE, IN CUBIC FEET PER SECOND, WATER YEAR OCTOBER 1997 TO SEPTEMBER 1998 DAILY MEAN VALUES
DAY	OCT	NOV	DEC	JAN	FEB	MAR	APR	MAY	JUN	JUL	AUG	SEP

1	3000	3080	3360	3290	e3600	7230	11000	15200	7970	14500	3930	4570
2	2970	2940	3320	3030	4440	7410	15000	14900	7870	12200	3970	4530
3	2940	2910	3450	3190	4920	7630	15100	14600	7810	11900	3970	4370
4	3160	2730	3460	3590	5110	7740	15200	14200	7420	13100	4350	4030
5	3020	2670	3360	4200	5120	7770	15300	13800	7050	12800	4900	3870

6	2520	3130	3410	5740	5130	7560	15500	13900	7010	12800	6700	3900
7	3120	3060	3400	6970	5150	7400	15500	13800	6720	12300	8740	3880
8	2670	3290	3420	7120	5030	7390	15900	16200	6610	13100	8970	3870
9	2710	3580	3490	7650	4550	8770	17700	18700	6540	11900	7860	3880
10	2760	3600	3470	7250	4750	9700	18700	19200	6880	10800	7490	3750

11	2620	3510	3660	5630	4870	9320	19000	18600	7300	10400	7530	3550
12	2570	3310	3480	4600	5870	8130	18700	17300	7530	9960	7030	3570
13	2540	3160	3500	e3900	7120	7690	18000	16000	8270	8670	6950	3500
14	2640	2680	3480	e3200	7390	7670	18200	15100	9110	8340	5870	3910
15	2630	3220	3330	e3000	7510	7410	18800	14600	8520	7670	6050	4280

16	2400	3120	3310	e3150	7150	6300	18700	14000	8800	7330	5960	4500
17	2770	3210	3410	e3400	6610	7390	19400	12800	9310	6620	5780	4890
18	2480	2770	3290	e4000	6600	6910	20400	11400	8630	6660	5750	5180
19	2330	2850	3280	e3800	6840	8060	20000	11300	11500	6410	5540	5330
20	2370	2850	3230	e3700	6980	9120	19100	10700	9750	6280	5260	5200

21	2370	3050	3310	e3550	6900	9490	18700	10200	10700	6360	5110	5120
22	2430	2890	3310	e3450	6860	9470	19500	10100	10300	5530	4950	4290
23	2470	3030	3310	e3350	6470	8840	19800	9490	9360	6210	4430	4120
24	2850	3290	3430	e3300	6600	8610	19400	9040	9440	5950	4550	4190
25	3100	3100	3420	e3260	6600	8370	18700	8880	9480	5390	5130	4160

26	3050	3130	3360	e3250	6470	7760	17600	8330	11200	5650	5460	3950
27	3070	3230	3320	e3220	6840	7700	17800	8300	18300	5520	5120	3960
28	3120	3190	3110	e3210	7120	7940	17300	8220	17800	4930	4980	3970
29	3320	3230	3180	e3200	---	7980	16800	8120	17400	4870	5320	4040
30	3220	3340	3320	e3200	---	7640	15800	8020	16400	4410	5160	3990

31	3150	---	3400	e3200	---	8070	---	8010	---	3820	5010	---

TOTAL	86370	93150	104580	126600	168600	248470	526600	393010	290980	262380	177820	126350
MEAN	2786	3105	3374	4084	6021	8015	17550	12680	9699	8464	5736	4212
MAX	3320	3600	3660	7650	7510	9700	20400	19200	18300	14500	8970	5330
MIN	2330	2670	3110	3000	3600	6300	11000	8010	6540	3820	3930	3500
CFSM	.32	.35	.39	.47	.69	.92	2.01	1.45	1.11	.97	.66	.48
IN.	.37	.40	.44	.54	.72	1.06	2.24	1.67	1.24	1.12	.76	.54

e Estimated

STATISTICS OF MONTHLY MEAN DATA FOR WATER YEARS 1935 - 1998, BY WATER YEAR (WY)
MEAN	3703	4562	4253	4464	5824	9691	9177	6613	5738	4995	3780	3783
MAX	9633	15900	14120	13200	18020	19970	25070	16660	20690	22030	10820	15630
(WY)	1955	1986	1983	1946	1938	1948	1993	1960	1996	1993	1993	1938
MIN	1210	1408	1411	1047	1353	2432	3305	1652	1848	885	1147	999
(WY)	1964	1950	1964	1940	1940	1968	1958	1958	1936	1936	1936	1958

SUMMARY STATISTICS	FOR 1997 CALENDAR YEAR		FOR 1998 WATER YEAR		WATER YEARS 1935 - 1998
ANNUAL TOTAL	2453740		2604910
ANNUAL MEAN	6723		7137		5580
HIGHEST ANNUAL MEAN					12990	1993
LOWEST ANNUAL MEAN					2187	1964
HIGHEST DAILY MEAN	39500 A	Feb 22	20400	Apr 18	45000	May 29 1996
LOWEST DAILY MEAN	2330	Oct 19	2330	Oct 19	524	Aug 9 1936
ANNUAL SEVEN-DAY MINIMUM	2450	Oct 16	2450	Oct 16	673	Aug 3 1936
INSTANTANEOUS PEAK FLOW			20400	Apr 18	59700 B	Apr 21 1973
INSTANTANEOUS PEAK STAGE			7.92	Apr 18	17.51 C	Feb 7 1938
INSTANTANEOUS LOW FLOW			2090	Oct 6	440	Aug 20 1934
ANNUAL RUNOFF (CFSM)	.77		.82		.64
ANNUAL RUNOFF (INCHES)	10.43		11.07		8.66
10 PERCENT EXCEEDS	10800		15200		10800
50 PERCENT EXCEEDS	5400		5540		4220
90 PERCENT EXCEEDS	3060		3060		1660

A - Estimated due to backwater from ice.
B - Gage height, 15.66 ft., from rating curve extended above 41,200 ft³/s.
C - Ice jam.

Table of Contents

Introduction

Station Descriptions

Surface-Water Data

Ground-Water Data

Meteorological Data

Biological Data