LOCATION.-- Lat 41°26'32", long 90°33'21" (NAD of 1927), in NW1/4NE1/4 sec.25, T.17 N., R.2 W., Rock Island County, Hydrologic Unit 07090005, on right bank 100 ft. upstream from Knoxville Road Bridge, 1 mi southeast of Milan, and at mile 1.2. | |
DRAINAGE AREA.-- 62.4 mi2. | |
PERIOD OF RECORD.-- | |
SURFACE-WATER DISCHARGE AND STAGE | |
DISCHARGE: March 1989 to current year. October 1939 to September 1940 (fragmentary), July 1941 to September 1986. Seven-month period (March to September), water years 1987-89. | |
STAGE: Water years 1999 to current year. | |
REVISED RECORDS.-- WSP 1308: 1940(M), 1943(M). WDR IL-72-1: Drainage area. | |
GAGE.-- Water-stage recorder, phone telemeter, and crest-stage gage. Datum of gage is 565.23 ft above NGVD of 1929 (levels by U.S. Army Corps of Engineers). Prior to Oct. 1, 1987, at datum 1.00 ft higher. Prior to Apr. 5, 1940, nonrecording gage at site 300 ft upstream. Oct. 1939 to Nov. 15, 1984, recording gage at site 400 ft. upstream. | |
REMARKS.-- Occasional pumpage of about 3-6 ft3/s from quarry into creek upstream from gage. | |
EXTREMES FOR PERIOD OF RECORD.-- | |
SURFACE-WATER DISCHARGE AND STAGE: Maximum discharge, 9,300 ft3/s, Apr. 22, 1973, gage height, 12.65 ft, present datum; no flow at times in several years. | |
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 | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| DAY | OCT | NOV | DEC | JAN | FEB | MAR | APR | MAY | JUN | JUL | AUG | SEP |
| 1 | 3.8 | 6.7 | 6.4 | 6.5 | e4.1 | e4.6 | 8.2 | 430 | 27 | 19 | 20 | 3.4 |
| 2 | 11 | 6.5 | 6.4 | 9.1 | e4.8 | e4.5 | 7.5 | 181 | 27 | 18 | 23 | 2.8 |
| 3 | 10 | 6.6 | 7.1 | 6.3 | e5.5 | e4.6 | 7.2 | 123 | 30 | 18 | 15 | 1.7 |
| 4 | 24 | 6.7 | 8.4 | 5.2 | e5.0 | e5.0 | 8.4 | 140 | 28 | 17 | 17 | 2.2 |
| 5 | 20 | 6.8 | 6.3 | 6.1 | e4.5 | e5.5 | 9.3 | 572 | 26 | 15 | 14 | 3.3 |
| 6 | 8.6 | 7.2 | 3.9 | 5.8 | e4.0 | e4.6 | 6.7 | 201 | 32 | 14 | 17 | 1.6 |
| 7 | 6.2 | 7.7 | 4.0 | 5.3 | e3.7 | e4.5 | 8.2 | 143 | 40 | 13 | 14 | 0.60 |
| 8 | 7.0 | 8.2 | 4.1 | 7.6 | e3.4 | e4.4 | 9.1 | 118 | 33 | 33 | 10 | 0.56 |
| 9 | 8.3 | 9.8 | 4.5 | 7.9 | e3.2 | e4.8 | 7.5 | 504 | 39 | 34 | 8.9 | 0.52 |
| 10 | 7.0 | 9.5 | 4.0 | 8.2 | e3.1 | e5.2 | 9.1 | 242 | 56 | 100 | 7.8 | 0.42 |
| 11 | 5.5 | 11 | 4.0 | e17 | e3.0 | e4.8 | 10 | 172 | 56 | 48 | 8.3 | 0.37 |
| 12 | 5.0 | 9.2 | 5.0 | e4.8 | e2.9 | 19 | 8.0 | 123 | 46 | 33 | 7.2 | 0.69 |
| 13 | 4.7 | 6.9 | 6.7 | e4.5 | e2.8 | 285 | 6.7 | 102 | 40 | 27 | 6.6 | 12 |
| 14 | 4.7 | 8.0 | 7.3 | e4.2 | e2.8 | 95 | 7.7 | 123 | 36 | 23 | 5.9 | 29 |
| 15 | 4.7 | 7.9 | 7.7 | e4.0 | e2.9 | 47 | 6.9 | 102 | 32 | 21 | 5.4 | 12 |
| 16 | 4.9 | 6.8 | 7.8 | e3.8 | e2.9 | 48 | 7.5 | 83 | 29 | 18 | 5.2 | 3.7 |
| 17 | 7.2 | 6.6 | 7.5 | e3.7 | e3.0 | 42 | 23 | 73 | 27 | 18 | 4.7 | 1.9 |
| 18 | 6.7 | 6.6 | 17 | e3.6 | e3.2 | 32 | 15 | 65 | 26 | 18 | 4.6 | 1.3 |
| 19 | 5.3 | 7.8 | 30 | e3.5 | e3.7 | 26 | 14 | 63 | 26 | 17 | 4.7 | 1.7 |
| 20 | 5.3 | 8.2 | 17 | e3.4 | e5.0 | 22 | 33 | 57 | 24 | 17 | 5.7 | 1.6 |
| 21 | 4.8 | 7.1 | 12 | e3.3 | e9.0 | 18 | 27 | 50 | 21 | 96 | 5.2 | 1.4 |
| 22 | 6.5 | 8.4 | 8.0 | e3.2 | e18 | 14 | 22 | 46 | 20 | 31 | 2.6 | 2.5 |
| 23 | 7.2 | 8.9 | 6.5 | e3.0 | e15 | 12 | 18 | 46 | 20 | 25 | 2.1 | 2.0 |
| 24 | 6.3 | 6.9 | 6.7 | e2.8 | e10 | 11 | 17 | 43 | 19 | 24 | 1.9 | 1.1 |
| 25 | 12 | 6.3 | 5.9 | e2.5 | e7.0 | 11 | 16 | 40 | 23 | 19 | 1.8 | 0.76 |
| 26 | 11 | 4.7 | 5.0 | e2.5 | e5.5 | 8.9 | 14 | 36 | 52 | 17 | 1.6 | 0.75 |
| 27 | 7.7 | 4.7 | 4.8 | e2.6 | e5.1 | 7.7 | 13 | 35 | 30 | 29 | 1.4 | 1.3 |
| 28 | 7.8 | 5.5 | 5.7 | e2.7 | e4.8 | 16 | 12 | 38 | 24 | 24 | 1.2 | 1.1 |
| 29 | 9.1 | 6.5 | 6.1 | e2.8 | --- | 19 | 16 | 36 | 22 | 19 | 1.2 | 0.94 |
| 30 | 7.2 | 7.3 | 10 | e3.2 | --- | 13 | 35 | 32 | 20 | 16 | 1.1 | 0.73 |
| 31 | 8.2 | --- | 10 | e3.6 | --- | 9.6 | --- | 30 | --- | 15 | 1.8 | --- |
| TOTAL | 247.7 | 221.0 | 245.8 | 152.7 | 147.9 | 808.7 | 403.0 | 4049 | 931 | 836 | 226.9 | 93.94 |
| MEAN | 7.99 | 7.37 | 7.93 | 4.93 | 5.28 | 26.1 | 13.4 | 131 | 31.0 | 27.0 | 7.32 | 3.13 |
| MAX | 24 | 11 | 30 | 17 | 18 | 285 | 35 | 572 | 56 | 100 | 23 | 29 |
| MIN | 3.8 | 4.7 | 3.9 | 2.5 | 2.8 | 4.4 | 6.7 | 30 | 19 | 13 | 1.1 | 0.37 |
| CFSM | 0.13 | 0.12 | 0.13 | 0.08 | 0.08 | 0.42 | 0.22 | 2.09 | 0.50 | 0.43 | 0.12 | 0.05 |
| IN. | 0.15 | 0.13 | 0.15 | 0.09 | 0.09 | 0.48 | 0.24 | 2.41 | 0.56 | 0.50 | 0.14 | 0.06 |
| e Estimated |
| STATISTICS OF MONTHLY MEAN DATA FOR WATER YEARS 1940 - 2003, BY WATER YEAR (WY) | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| MEAN | 22.5 | 23.7 | 26.2 | 37.5 | 63.1 | 76.1 | 78.7 | 76.1 | 69.8 | 41.2 | 24.6 | 18.6 |
| MAX | 209 | 175 | 162 | 223 | 261 | 299 | 335 | 432 | 616 | 388 | 259 | 208 |
| (WY) | 1955 | 1962 | 1983 | 1960 | 2001 | 1960 | 1965 | 1996 | 1993 | 1986 | 1993 | 1970 |
| MIN | 0.11 | 0.51 | 0.44 | 0.000 | 2.78 | 3.95 | 3.17 | 3.44 | 1.86 | 1.50 | 0.89 | 0.18 |
| (WY) | 1957 | 1957 | 1977 | 1940 | 1964 | 1956 | 1956 | 1956 | 1956 | 1988 | 1957 | 1956 |
| SUMMARY STATISTICS | FOR 2002 CALENDAR YEAR | FOR 2003 WATER YEAR | WATER YEARS 1940 - 2003 | |||
|---|---|---|---|---|---|---|
| ANNUAL TOTAL | 16667.3 | 8363.64 | ||||
| ANNUAL MEAN | 45.7 | 22.9 | 47.8 | |||
| HIGHEST ANNUAL MEAN | 173 | 1993 | ||||
| LOWEST ANNUAL MEAN | 8.67 | 1957 | ||||
| HIGHEST DAILY MEAN | 807 | May 12 | 572 | May 5 | 5000 | Jul 8 1986 |
| LOWEST DAILY MEAN | 3.8 | Sep 30-Oct 1 | 0.37 | Sep 11 | 0.00 | A |
| ANNUAL SEVEN-DAY MINIMUM | 4.2 | Dec 6 | 0.68 | Sep 6 | 0.00 | Dec 30 1939 |
| MAXIMUM PEAK FLOW | 1170 | May 5 | 9300 | Apr 22 1973 | ||
| MAXIMUM PEAK STAGE | 5.46 | May 5 | 12.65 B | Apr 22 1973 | ||
| INSTANTANEOUS LOW FLOW | 0.28 | Sep 11 | ||||
| ANNUAL RUNOFF (CFSM) | 0.73 | 0.37 | 0.77 | |||
| ANNUAL RUNOFF (INCHES) | 9.94 | 4.99 | 10.42 | |||
| 10 PERCENT EXCEEDS | 95 | 41 | 96 | |||
| 50 PERCENT EXCEEDS | 24 | 7.8 | 18 | |||
| 90 PERCENT EXCEEDS | 6.3 | 2.7 | 1.8 | |||
|