LOCATION.-- Lat 41°46'58", long 89°44'59" (NAD of 1927), 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. |
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DRAINAGE AREA.-- 8,753 mi2. |
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PERIOD OF RECORD.-- |
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SURFACE-WATER DISCHARGE AND STAGE |
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DISCHARGE: March to December 1905, October 1914 to September 1971, 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. |
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STAGE: Water years 1994 to current year. |
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PARTIAL RECORD: Annual maximum, water years 1972-77. |
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SURFACE-WATER QUALITY |
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CHEMICAL: Water years 1978-91. |
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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). |
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GAGE.-- Water-stage recorder, U.S. Army Corps of Engineers satellite telemeter and rain gage, and crest-stage gage. Datum of gage is 606.83 ft above NGVD of 1929. 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. |
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REMARKS.-- Some diurnal fluctuation caused by powerplants upstream from station. |
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EXTREMES FOR PERIOD OF RECORD.-- |
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SURFACE-WATER DISCHARGE AND STAGE: 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, ice jam; minimum discharge, 390 ft3/s, July 27, 2003, as a result of regulation. |
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REMARKS FOR CURRENT YEAR.-- Records good except those for estimated daily discharges, which are poor. |
Discharge, cubic feet per second, WATER YEAR OCTOBER 2002 TO SEPTEMBER 2003 DAILY MEAN VALUES |
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DAY | OCT | NOV | DEC | JAN | FEB | MAR | APR | MAY | JUN | JUL | AUG | SEP |
1 | 4200 | 4240 | 3800 | 3440 | e2400 | 2710 | 3940 | 3220 | 6300 | 2470 | 2290 | 1360 |
2 | 3310 | 4110 | 3490 | 3360 | e2500 | 2660 | 3930 | 4260 | 6350 | 2340 | 2740 | 1260 |
3 | 5770 | 4200 | 3730 | 3140 | e2700 | 2960 | 3920 | 5040 | 6050 | 2280 | 2530 | 1240 |
4 | 5440 | 4160 | 3180 | 2870 | 3220 | 2800 | 4060 | 6260 | 5420 | 2280 | 2380 | 1300 |
5 | 6330 | 4240 | 2920 | 2790 | 3720 | 2630 | 3140 | 6780 | 5190 | 2690 | 2350 | 1310 |
6 | 6840 | 3960 | 3180 | 2840 | 3570 | 2330 | 4090 | 7890 | 5120 | 1990 | 2410 | 1260 |
7 | 6860 | 4010 | 2830 | 2930 | 3490 | 2820 | 3960 | 8390 | 5070 | 2750 | 2270 | 1210 |
8 | 6170 | 4070 | 3370 | 3040 | e3400 | 2840 | 3780 | 7960 | 4660 | 3540 | 2120 | 1230 |
9 | 6140 | 3490 | 3890 | 2880 | e3300 | 2770 | 3750 | 7870 | 4510 | 3560 | 2170 | 1150 |
10 | 6140 | 3620 | 2820 | 3110 | e3200 | 2610 | 3860 | 8720 | 4550 | 4540 | 2150 | 1070 |
11 | 5280 | 3940 | 3080 | 3360 | e3100 | 2490 | 3520 | 9230 | 4640 | 4330 | 2170 | 1190 |
12 | 5240 | 4130 | 3360 | 3180 | e3100 | 2490 | 3740 | 10500 | 4490 | 4600 | 2080 | 1160 |
13 | 4440 | 3980 | 3780 | 2620 | e3000 | 2530 | 3630 | 9830 | 4350 | 3960 | 1970 | 1370 |
14 | 4440 | 3860 | 3270 | 2590 | e3000 | 2630 | 3440 | 10200 | 4110 | 3660 | 1910 | 1480 |
15 | 4110 | 3720 | 3310 | e2700 | 3300 | 2640 | 3600 | 10400 | 4130 | 3720 | 1950 | 1860 |
16 | 4380 | 3810 | 3520 | e2800 | 3660 | 2720 | 3530 | 10700 | 4160 | 5030 | 2010 | 2430 |
17 | 4050 | 3890 | 3370 | e3000 | 3590 | 3050 | 3260 | 10300 | 4220 | 5240 | 1960 | 2190 |
18 | 4120 | 3710 | 3320 | e3000 | 3260 | 3840 | 3090 | 9970 | 4140 | 4390 | 1830 | 1950 |
19 | 4200 | 3800 | 3580 | e3000 | 2910 | 4130 | 2870 | 9130 | 4370 | 3730 | 1750 | 2020 |
20 | 4190 | 3840 | 3550 | e2800 | 2700 | 4060 | 2660 | 9740 | 4300 | 3570 | 1670 | 2270 |
21 | 4030 | 3710 | 3870 | e2650 | 2630 | 4130 | 2500 | 9230 | 4350 | 3980 | 1640 | 2040 |
22 | 4100 | 3720 | 3830 | e2550 | 2570 | 4280 | 2830 | 8930 | 4090 | 3310 | 1700 | 1830 |
23 | 4070 | 3710 | 3750 | e2400 | 3000 | 3830 | 3050 | 8690 | 3770 | 3280 | 1450 | 1800 |
24 | 4180 | 3760 | 3640 | e2320 | 2840 | 3810 | 3130 | 8430 | 4050 | 3290 | 1390 | 1970 |
25 | e4500 | 3990 | 3600 | e2300 | 2970 | 3960 | 3120 | 8030 | 4650 | 3200 | 1670 | 1780 |
26 | e3900 | 3630 | 3850 | e2200 | 2900 | 3530 | 3410 | 7560 | 2160 | 2860 | 1360 | 1660 |
27 | 4280 | 3670 | 3400 | e2200 | 2860 | 3890 | 3460 | 7040 | 3010 | 2570 | 1420 | 1710 |
28 | 4280 | 3460 | 3210 | e2250 | 2790 | 4080 | 3480 | 6700 | 2530 | 2800 | 1470 | 1800 |
29 | 3700 | 3120 | 3210 | e2150 | --- | 4150 | 3600 | 6530 | 2380 | 1820 | 1280 | 1660 |
30 | 3950 | 3730 | 3260 | e2300 | --- | 4060 | 3740 | 6090 | 2580 | 2280 | 1250 | 1680 |
31 | 4430 | --- | 3540 | e2300 | --- | 4070 | --- | 6170 | --- | 2250 | 1320 | --- |
TOTAL | 147070 | 115280 | 106510 | 85070 | 85680 | 101500 | 104090 | 249790 | 129700 | 102310 | 58660 | 48240 |
MEAN | 4744 | 3843 | 3436 | 2744 | 3060 | 3274 | 3470 | 8058 | 4323 | 3300 | 1892 | 1608 |
MAX | 6860 | 4240 | 3890 | 3440 | 3720 | 4280 | 4090 | 10700 | 6350 | 5240 | 2740 | 2430 |
MIN | 3310 | 3120 | 2820 | 2150 | 2400 | 2330 | 2500 | 3220 | 2160 | 1820 | 1250 | 1070 |
CFSM | 0.54 | 0.44 | 0.39 | 0.31 | 0.35 | 0.37 | 0.40 | 0.92 | 0.49 | 0.38 | 0.22 | 0.18 |
IN. | 0.63 | 0.49 | 0.45 | 0.36 | 0.36 | 0.43 | 0.44 | 1.06 | 0.55 | 0.43 | 0.25 | 0.21 |
e Estimated |
STATISTICS OF MONTHLY MEAN DATA FOR WATER YEARS 1935 - 2003, BY WATER YEAR (WY) | ||||||||||||
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MEAN | 3872 | 4611 | 4272 | 4431 | 5965 | 9533 | 9151 | 6926 | 6374 | 5078 | 3839 | 3833 |
MAX | 9633 | 15900 | 14120 | 13200 | 18020 | 19970 | 25070 | 16660 | 24500 | 22030 | 10820 | 15630 |
(WY) | 1955 | 1986 | 1983 | 1946 | 1938 | 1948 | 1993 | 1960 | 2000 | 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 2002 CALENDAR YEAR | FOR 2003 WATER YEAR | WATER YEARS 1935 - 2003 | |||
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ANNUAL TOTAL | 2383470 | 1333900 | ||||
ANNUAL MEAN | 6530 | 3655 | 5690 | |||
HIGHEST ANNUAL MEAN | 12990 | 1993 | ||||
LOWEST ANNUAL MEAN | 2187 | 1964 | ||||
HIGHEST DAILY MEAN | 45200 | Jun 5 | 10700 | May 16 | 45200 | A |
LOWEST DAILY MEAN | 2150 | Aug 21 | 1070 | Sep 10 | 524 | Aug 9 1936 |
ANNUAL SEVEN-DAY MINIMUM | 2860 | Aug 6 | 1180 | Sep 6 | 673 | Aug 3 1936 |
MAXIMUM PEAK FLOW | 11400 | May 12 | 59700 B | Apr 21 1973 | ||
MAXIMUM PEAK STAGE | 5.43 | May 12 | 17.51 C | Feb 7 1938 | ||
INSTANTANEOUS LOW FLOW | 390 D | Jul 27 | 390 D | Jul 27 2003 | ||
ANNUAL RUNOFF (CFSM) | 0.75 | 0.42 | 0.65 | |||
ANNUAL RUNOFF (INCHES) | 10.13 | 5.67 | 8.83 | |||
10 PERCENT EXCEEDS | 11000 | 6070 | 11000 | |||
50 PERCENT EXCEEDS | 4940 | 3410 | 4300 | |||
90 PERCENT EXCEEDS | 3310 | 1830 | 1700 |
B - Gage height, 15.66 ft, from rating curve extended above 41,200 ft/3s. |
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Table of Contents |
Introduction |
Station Descriptions |
Surface-Water Data |
Ground-Water Data |
Meteorological Data |
Biological Data |